referring to fig1 , a spray apparatus according to one illustrative embodiment is shown generally at 100 . u . s . pat . nos . 6 , 394 , 321 and 6 , 581 , 807 describe aerosol containers that may be suitable for spraying powder , and in some embodiments the spray apparatus 100 may be similar to one of the aerosol containers described and illustrated in u . s . pat . nos . 6 , 394 , 321 and 6 , 581 , 807 or to other aerosol containers that may be suitable for spraying powder . the spray apparatus 100 in the embodiment shown includes a body 102 defining a reservoir 104 therein . the body 102 may include a steel can , and the body 102 in the embodiment shown is thus a rigid container . alternative embodiments may include or other material suitable , such as other rigid containers for example , for holding pressurized air . for example , the body 102 in one embodiment may be a steel can having a size known to one skilled in the art as “ 202 × 509 ” ( or 2 2 / 16 inches in diameter and 5 9 / 16 inches in height , or about 5 . 4 centimetres (“ cm ”) in diameter and about 14 . 1 cm in height ) and having an inner epoxy coating , and which may be sized so that the reservoir 104 holds 170 grams of contents 106 . the body 102 thus holds the contents 106 , although alternative embodiments may include different structures to hold the contents 106 . for example , in some embodiments , the body 102 may include a tin - plated steel can with a protective liner . in the embodiment shown , the contents 106 include diatomaceous earth 108 and a propellant , which in some embodiments may be a mixture of isobutane and propane known to one skilled in the art as propellant a - 46 , and which in some embodiments may include about 75 % isobutane and about 25 % propane . in other embodiments , the propellant may be a liquefied petroleum gas known to one skilled in the art as propellant blend a - 70 available from brenntag canada inc . of toronto , ontario , canada . in the embodiment shown , the propellant is in a gaseous phase 110 , and also in a liquid phase 112 intermixed with the diatomaceous earth 108 . further , the contents 106 in the embodiment shown include an unmatured anhydrous alcohol 114 intermixed with the diatomaceous earth 108 . the alcohol 114 may be denatured with fragrance , resin , a product known as bitrex ™, or another product for example . the alcohol 114 may include an alcohol known to one skilled in the art as sd - 40 or sdag - 6 , for example . in some embodiments , such alcohol 114 may evaporate generally rapidly one sprayed from the spray apparatus 100 , thereby leaving dried diatomaceous earth 108 on a surface ( not shown ) sprayed by the spray apparatus 100 . in the embodiment shown , the alcohol 114 is about 54 % by weight of the contents 106 , the propellant is about 38 % by weight of the contents 106 , and the diatomaceous earth 108 is about 8 % by weight of the contents 106 . in other embodiments , the diatomaceous earth 108 may be at least 3 % by weight of the contents 106 , at least 5 % by weight of the contents 106 , or at least 7 % by weight of the contents 106 , for example , and in such embodiments the propellant may be more than about 38 % by weight of the contents 106 and / or the alcohol 114 may be more than about 54 % by weight of the contents 106 . in still other embodiments , products other than diatomaceous earth , such as other products that may be effective to control bedbug populations or more generally as an insecticide or pesticide for example , may be intermixed with the diatomaceous earth 108 . for example , u . s . pat . no . 8 , 101 , 408 describes various legume extracts , such as one or more of pa1b - related peptides , terpenoid saponins , triterpenoid saponin , soyasaponin i , soyasaponin ii , soyasaponin iii , soyasaponin vi , dehydrosoyasaponin i , echinocystic acid 3 - glucoside , glycyrrhizic acid , hederacoside c , beta - escin , alpha - hederin , and other acetic acid precipitated insecticidal components . in various embodiments , such legume extracts may be intermixed with the diatomaceous earth 108 , and in such embodiments the propellant may be less than about 38 % by weight of the contents 106 and / or the alcohol 114 may be less than about 54 % by weight of the contents 106 . one skilled in the art will appreciate that the contents 106 need not be exactly in the aforementioned proportions , that the spray apparatus 100 may function similarly with more or less of those components , and that “ about ” in this context means refers to variations of the aforementioned proportions that allow the spray apparatus 100 to function with similar results . the spray apparatus 100 also includes an aerosol valve assembly shown generally at 116 and including a tube 118 , a valve housing 120 receiving the tube 118 at the bottom of the valve housing 120 , a valve - closing coil spring 122 , and a valve body 124 having a hollow valve stem 126 defining lateral openings 128 extending into the interior of the valve stem 126 . a gasket 130 surrounds the valve stem 126 and seals the openings 128 when the aerosol valve is closed . an actuator 132 is attached to the top of the valve stem 126 such that an outlet nozzle 134 of the actuator 132 is in fluid communication with the interior of the valve stem 126 . further , the reservoir 104 includes a ball bearing or marble 136 to facilitate mixing the contents 106 when the spray apparatus 100 is shaken . for example , in one embodiment , the spray apparatus 100 may be shaken for about 8 to about 10 seconds , or vigorously for about 10 seconds , to achieve desirable mixing of the contents 106 before the contents 106 are sprayed from the spray apparatus 100 . one skilled in the art will appreciate numerous variations from the spray apparatus 100 . for example , alternative embodiments may include various alternative cans , valves , and actuators . for example , one embodiment may include a valve suitable for power and coated on a top side to prevent rusting , such as a valve known to one skilled in the art as prec . powder valve s . 2x . 020 ringed barb 630 ( oal ) ( 04 - 0519 - 42 ) g . hex buna b175 b . 080x . 030vt 412 deep mc con . epon top lam . bot dimp . dt 138 mm a - d , and an actuator known to one skilled in the art as act . 025 ″ nmbu raised apsl 0 . 022 white ( 21 - 9116 - 00 - 0343 ). various embodiments may also include a cap ( not shown ) to protect the actuator from being actuated unintentionally , such as during shipping for example . alternative embodiments may also include different contents , such as different propellants for example . some embodiments of the spray apparatus 100 or alternative embodiments may be prepared by a batch process . the description below is one example of a manufacturing process for 1 , 000 kilograms of formulated product . first , 540 kilograms of anhydrous ethyl alcohol is held in a clean and dry stainless steel tank , and 80 kilograms of diatomaceous earth powder is then added slowly ( to avoid clumping ) to the anhydrous ethyl alcohol under medium mixing using an air mixer until homogeneous to form a bulk concentrate of 620 kilograms . the mixing may require about 15 minutes . then , portions of the bulk concentrate are metered through a filter into aerosol containers at a temperature between 68 ° f . ( about 20 ° c .) and 73 ° f . ( about 22 . 8 ° c .). for an aerosol container having a size known to one skilled in the art as “ 211 × 604 ” ( or 2 11 / 16 inches in diameter and 6 4 / 16 inches in height , or about 6 . 8 cm in diameter and about 15 . 9 cm in height ), 186 grams of bulk concentrate may be added , and for an aerosol container having a size known to one skilled in the art as “ 211 × 713 ” ( or 2 11 / 16 inches in diameter and 7 13 / 16 inches in height , or about 6 . 8 cm in diameter and about 19 . 8 cm in height ), 248 grams of bulk concentrate may be added . each aerosol container may then be fitted with an aerosol valve and subjected to a vacuum at 15 inches of mercury ( about 50 . 8 kilopascals ) to 20 inches of mercury ( about 67 . 7 kilopascals ). the propellant ( a - 70 in this example ) may then be metered under pressure into each aerosol container at a temperature between 65 ° f . ( about 18 . 3 ° c .) and 70 ° f . ( about 21 . 1 ° c .) and at a pressure of 600 pound - force per square inch gauge ( about 4 , 238 kilopascals ) to 650 pound - force per square inch gauge ( about 4 , 583 kilopascals ), and each aerosol container may be then crimped shut . for an aerosol container having a size known to one skilled in the art as “ 211 × 604 ” ( or 2 11 / 16 inches in diameter and 6 4 / 16 inches in height , or about 6 . 8 cm in diameter and about 15 . 9 cm in height ), 114 grams of propellant may be added , and for an aerosol container having a size known to one skilled in the art as “ 211 × 713 ” ( or 2 11 / 16 inches in diameter and 7 13 / 16 inches in height , or about 6 . 8 cm in diameter and about 19 . 8 cm in height ), 152 grams of propellant may be added . the aerosol containers may then be placed in a hot water bath of 130 ° f . ( about 54 ° c .) to 140 ° f . ( about 60 ° c .) for about 30 seconds to test the strength of the aerosol containers . an outer cap , a label , and lot number may then be placed on each aerosol container , and the aerosol containers may be packaged in boxes for distribution . the label may include precautionary information , such as markings not to use the aerosol container in the presence of an open flame or a spark , or while smoking , a warning that the aerosol container may explode if heated , a warning not to expose to temperatures above 50 ° c . or 122 ° f ., and a warning not puncture or incinerate for example . in operation , when the actuator 132 is pressed towards the body 102 against the force of the spring 122 , the openings 128 pass below the gasket 130 to open controllably the openings 128 and thus controllably allow the contents 106 pass through the tube 118 , through the openings 128 , into the valve stem 126 , into the actuator 132 , and to be sprayed out the nozzle 134 under pressure from the propellant . when the actuator 132 is released , the spring 122 urges the valve stem 126 to the a position where the openings 128 are blocked by the gasket 130 to close the aerosol valve and prevent the contents 106 from entering into the valve stem under pressure from the propellant . therefore , the nozzle 134 may controllably release the propellant , and the diatomaceous earth 108 propelled by the propellant , from the reservoir 104 . numerous types of diatomaceous earth are available and vary , for example , on the sizes , shapes , and species of diatoms that contributed to the diatomaceous earth . the diatomaceous earth 108 in some embodiments may include celatom ™ mn - 51 , which is available from ep minerals , llc of 9785 gateway drive , suite 1000 , reno , nev ., united states of america . the diatomaceous earth known as celatom ™ mn - 51 is believed to be a food - grade diatomaceous earth that originates from a deposit formed from fresh - water diatoms at clark station , nev ., united states of america , and that may be heat - treated or flash dried at about 900 ° f . ( about 480 ° c .) or at other temperatures , for example . in one embodiment , flash drying diatomaceous earth involves heating the diatomaceous earth at about 900 ° f . ( about 480 ° c .) for about 15 seconds . fig2 to 5 are secondary electron images ( using a philips xl - 30 scanning electron microscope after coating with evaporated gold ) of the diatomaceous earth known as celatom ™ mn - 51 . the scale bars in fig3 to 5 represent 30 micrometers in those figures . the diatomaceous earth known as celatom ™ mn - 51 is believed to have the properties given in table 1 below . a sample of the diatomaceous earth known as celatom ™ mn - 51 was reduced in size to less than 10 micrometers for quantitative x - ray analysis by grinding under ethanol in a vibratory mccrone micronising mill for seven minutes . step - scan x - ray powder - diffraction data were collected over a range 3 - 80 ° 2θ with coka radiation on a bruker d8 focus bragg - brentano diffractometer equipped with an fe monochromator foil , 0 . 6 mm ( 0 . 3 °) divergence slit , incident - and diffracted - beam soller slits , and a lynxeye detector . the long fine - focus co x - ray tube was operated at 35 kv and 40 ma , using a take - off angle of 6 °. the x - ray diffractograms were analyzed using the international centre for diffraction database pdf - 4 and search - match software by siemens ( bruker ). x - ray powder - diffraction data of the sample were refined with rietveld program topas 4 . 2 ( bruker axs ). fig6 is a rietveld refinement plot of the diatomaceous earth known as celatom ™ mn - 51 . fig6 shows observed intensity at each step and a calculated pattern , and the line below the graph shows the difference between the observed and calculated intensities . the other lines in the graph show individual diffraction patterns of all phases , and the vertical bars represent positions of all bragg reflections . the amounts given on fig6 are renormalized amorphous - free . the sample contained abundant montmorillonite , which exhibits stacking disorder , so the crystal structure is not predictable . an empirical model was used to account for this phase . in addition , the contribution of amorphous silica was modeled with a peak phase and its amount estimated . the results may be considered semi - quantitative and are in table 2 below . particle sizes of sample of the diatomaceous earth known as celatom ™ mn - 51 were measured in a mastersizer ™ 2000 in a water dispersant , and fig7 is a graph of particle size distribution of the diatomaceous earth known as celatom ™ mn - 51 . in an alternative embodiment , the diatomaceous earth may include diatomaceous earth known as celatom ™ mn - 53 , which is also available from ep minerals , llc of 9785 gateway drive , suite 1000 , reno , nev ., united states of america . fig8 is a secondary electron image ( using a philips xl - 30 scanning electron microscope after coating with evaporated gold ) of the diatomaceous earth known as celatom ™ mn - 53 . the diatomaceous earth known as celatom ™ mn - 53 is believed to have the properties given in table 3 below . fig9 is a rietveld refinement plot of the diatomaceous earth known as celatom ™ mn - 53 obtained as described above for fig6 . fig9 shows observed intensity at each step and a calculated pattern , and the line below the graph shows the difference between the observed and calculated intensities . the other lines in the graph show individual diffraction patterns of all phases , and the vertical bars represent positions of all bragg reflections . the amounts given on fig9 are renormalized amorphous - free . the results of phase analysis of celatom ™ mn - 53 by rietveld refinements are in table 4 below . fig1 is a secondary electron image ( using a philips xl - 30 scanning electron microscope after coating with evaporated gold ) of diatomaceous earth known as alpine ™ dust (“ prescription treatment brand ”) obtained from whitmire micro - gen research laboratories , inc . of st . louis , mo ., united states of america , and fig1 is a rietveld refinement plot of the diatomaceous earth known as alpine ™ dust obtained as described above for fig6 . fig1 shows observed intensity at each step and a calculated pattern , and the line below the graph shows the difference between the observed and calculated intensities . the other lines in the graph show individual diffraction patterns of all phases , and the vertical bars represent positions of all bragg reflections . the amounts given on fig1 are renormalized amorphous - free . the results of phase analysis of alpine ™ dust by rietveld refinements are in table 5 below . fig1 is a secondary electron image ( using a philips xl - 30 scanning electron microscope after coating with evaporated gold ) of diatomaceous earth known as motherearth ™ d obtained from whitmire micro - gen research laboratories , inc . of st . louis , mo ., united states of america , and fig1 is a rietveld refinement plot of the diatomaceous earth known as motherearth ™ d obtained as described above for fig6 . fig1 shows observed intensity at each step and a calculated pattern , and the line below the graph shows the difference between the observed and calculated intensities . the other lines in the graph show individual diffraction patterns of all phases , and the vertical bars represent positions of all bragg reflections . the amounts given on fig1 are renormalized amorphous - free . the results of phase analysis of motherearth ™ d by rietveld refinements are in table 6 below . particle sizes of sample of the diatomaceous earth known as motherearth ™ d were measured in a mastersizer ™ 2000 in a water dispersant , and fig1 is a graph of particle size distribution of the diatomaceous earth known as motherearth ™ d . fig1 to 17 are secondary electron images ( using a philips xl - 30 scanning electron microscope after coating with evaporated gold ) of diatomaceous earth known as pro - active ™ obtained from pest control direct ltd ., hailsham , east sussex , united kingdom , and fig1 is a rietveld refinement plot of the diatomaceous earth known as pro - active ™ obtained as described above for fig6 . fig1 shows observed intensity at each step and a calculated pattern , and the line below the graph shows the difference between the observed and calculated intensities . the other lines in the graph show individual diffraction patterns of all phases , and the vertical bars represent positions of all bragg reflections . the amounts given on fig1 are renormalized amorphous - free . the results of phase analysis of pro - active ™ by rietveld refinements are in table 7 below . in one experiment (“ experiment # 1 ”), small plastic petri dishes available from gelman sciences ™, each about 5 . 0 cm or about 2 . 0 inches in diameter , were used in bioassays . a small opening of about 1 . 5 cm ( or about 0 . 6 inches ) in diameter was cut in the lid and closed with a piece of gauze to allow air for bedbug breathing . the petri dishes were lined with a filter paper about 4 . 25 cm ( or about 1 . 7 inches ) in diameter . diatomaceous earth was weighed and spread uniformly over the filter paper with forceps . ten adult field - collected common bedbugs ( cimex lectularius ) were introduced in each of the petri dishes , and the lids were placed over them to prevent their escape . petri dishes were transferred in a plastic box lined with paper towels sprayed with water to maintain humidity in the box . experiments were conducted at room temperature , and mortality was noted 24 , 48 , 72 , and 96 hours after the bedbugs were introduced into of the petri dishes . four concentrations , between about 0 . 5 milligrams (“ mg ”) and about 2 . 0 mg , were used to calculate a lowest lethal concentration sufficient to kill 50 % of the bedbugs (“ lc 50 ”) of each product . there was a single replication of 10 bedbugs each . tables 8 and 9 below show mortality data from experiment # 1 , where “ l ” refers to a number of bedbugs still living after a corresponding time given in the tables , and where “ d ” refers to a number that died after the time given . all of the bedbugs died in celatom ™ mn - 51 diatomaceous earth after 48 hours . therefore , lc 50 for celatom ™ mn - 51 was calculated for 48 hours only , and lc 50 after 48 hours for celatom ™ mn - 51 was calculated as 0 . 7 mg . the data after 48 hours for celatom ™ mn - 53 were not good for calculation , and therefore lc 50 for celatom ™ mn - 53 was calculated after 96 hours as 0 . 8 mg ( 0 . 552 - 1 . 052 ). in another experiment (“ experiment # 2 ”), mortality of celatom ™ mn - 51 was compared with the diatomaceous earth products known as alpine ™ dust , motherearth ™ d , and pro - active ™. the various products were applied with forceps and weighed on a small filter paper , which was then placed in a petri dish ( about 5 . 0 cm or about 2 inches diameter ). common bedbugs ( cimex lectularius ) were introduced in the various petri dishes , and mortality was assessed in each of the petri dishes after 24 hours and after 48 hours . four to five concentrations of each product were used , the concentrations ranging from 0 . 25 mg to 6 mg , and there were three replications of between 9 and 11 bedbugs ( adults or last instar nymphs ) in each replication . a probit analysis was used to calculate lc 50 and lc 95 ( lowest lethal concentrations sufficient to kill 95 % of the bedbugs ) values and 95 % confidence intervals (“ cis ”) for the lc 50 and lc 95 values , as shown in table 10 below . in another experiment (“ experiment # 3 ”), six petri dishes ( each about 5 . 0 cm or about 2 . 0 inches in diameter ) were sprayed with an aerosol including celatom ™ mn - 51 using an apparatus similar to the spray apparatus 100 shown in fig1 , and a thin coating of the celatom ™ mn - 51 remained after drying ; those six petri dishes were used for an experimental group . an additional six petri dishes ( each 5 . 0 cm or about 2 . 0 inches in diameter ) did not receive the aerosol or the diatomaceous earth ; those six petri dishes were used for a control group . five adult common bedbugs ( cimex lectularius ) were introduced with forceps into each of the 12 petri dishes , and lids were applied to prevent the bedbugs from escaping . mortality was assessed 3 , 15 , 18 , and 24 hours after the bedbugs were introduced into the petri dishes , and there was no mortality in the control group . mortality in the experimental group is shown in table 11 below . thus , in experiment # 3 , all of the bedbugs exposed to the aerosol including celatom ™ mn - 51 died within 24 hours , whereas none of the control group bedbugs died within 24 hours . another experiment (“ experiment # 4 ”) involved plastic rubbermaid ™ translucent boxes ( about 73 . 6 cm × about 45 . 7 cm × about 33 . 7 cm , or about 29 inches × about 18 inches × about 13 . 3 inches ), more particularly two such boxes as experimental boxes and two such boxes as control boxes . a section about 20 cm ( or about 7 . 9 inches ) wide in the center of each of the experimental boxes was sprayed with the aerosol including celatom ™ mn - 51 and allowed to dry . a piece of a field - collected sheet ( about 50 cm × about 24 cm , or about 19 . 7 inches × about 7 . 9 inches ) was lined on one side of each of the boxes and used as a stimulant . the sheet was collected from a home infested with bedbugs , and had eggs and many freshly fed bedbugs , but the bedbugs were collected from the sheet before placing pieces of the sheet into the boxes . sides of the boxes opposite the pieces of the field - collected sheet were lined with a clean and new piece of cloth . fifty adult common bedbugs ( cimex lectularius ) were introduced into each box on the clean cloth , and then the box was closed with a lid . the control boxes were similar to the experimental boxes but did not include the aerosol . in all four of the boxes , the bedbugs moved from the sides of the boxes having the clean cloths to the sides of the boxes having the pieces of the field - collected sheet . there was no mortality in the control boxes after 48 hours , but after 24 hours , one of the experimental boxes had mortality of 43 of the 50 bedbugs , and the other of the experimental boxes had mortality of 45 of the 50 bedbugs . all of the bedbugs in the experimental boxes died after 48 hours . the bedbugs were found dead lying on their backs and dusted with the product from the aerosol . another experiment (“ experiment # 5 ”) was the same as experiment # 4 except that 100 common bedbugs ( cimex lectularius ) were introduced on the clean piece of cloth as described for experiment # 4 . insects again moved from one side of the box to the other in all cases . there was no mortality in the control boxes , whereas after 18 hours , 99 bedbugs died in one of the experimental boxes and 98 bedbugs died in the other one of the experimental boxes . all of the bedbugs in both experimental boxes died after 24 hours . in one experiment ( experiment # 6 ), 1 . 5 mg of diatomaceous earth was placed on a piece of filter paper . one adult common bedbug ( cimex lectularius ) ( the “ treaded bedbug ”) was dusted by introducing it on the filter paper using forceps . the treated bedbug was then introduced in a petri dish ( about 5 . 0 cm or about 2 . 0 inches in diameter ) containing 4 untreated adult common bedbugs ( cimex lectularius ). both celatom ™ mn - 51 and motherearth ™ d diatomaceous earths were tested using this method . control petri dishes contained five bedbugs , none of which was dusted with diatomaceous earth . there were six replications with five bedbugs in each . petri dishes were placed in a plastic box with a lid , and mortality was assessed after 24 hours , 48 hours , and 96 hours . table 12 below shows the number of bedbugs dead in each of the six replications for celatom ™ mn - 51 , motherearth ™ d , and control petri dishes after 24 hours , 48 hours , and 96 hours . in another experiment ( experiment # 7 ), 2 . 0 mg of either celatom ™ mn - 51 or motherearth ™ d diatomaceous earth was mixed with a red fluorescent dust from a luminous powder kit # 1162a obtained from bioquip products inc ., rancho dominguez , calif ., united states of america and placed on a piece of filter paper . one adult common bedbug ( cimex lectularius ) was dusted by introducing it on the filter paper using forceps . the dusted bedbug was then introduced in a petri dish ( about 5 . 0 cm or about 2 . 0 inches in diameter ) containing 4 untreated adult common bedbugs ( cimex lectularius ). all petri dishes were then placed in a plastic box with a lid . control petri dishes contained five adult common bedbugs ( cimex lectularius ), none of which has been dusted with diatomaceous earth . there were three replications of each condition , and mortality was assessed after 16 hours . the mortality data are shown in table 13 below . the fluorescent dye was visibly observed on the bedbugs that did not contact the diatomaceous earth directly , suggesting that such bedbugs came into contact with diatomaceous earth by contacting the bedbug that had contacted the diatomaceous earth directly . in another experiment (“ experiment # 8 ”), diatomaceous earth dusts were weighed on filter paper ( fisher ™ brand , about 5 . 5 cm or about 2 . 2 inches in diameter ). the filter papers were shaken about 3 or 4 times to remove excess dust and were weighed again to measure diatomaceous earth remaining on the paper . table 14 below shows the weight of dust before shaking , the weight of dust remaining after shaking , and the amount lost from shaking as the difference between the weight of dust before shaking and the weight of dust after shaking . similarly , filter paper was weighed , sprayed with aerosol , dried , and weighed again to measure the diatomaceous earth residue . there were three replications for each diatomaceous earth sample tested . table 15 below shows weights of filter paper before and after spraying aerosol with diatomaceous earth , and amounts of diatomaceous earth added from spraying . in another experiment (“ experiment # 9 ”), a sample of celatom ™ mn - 51 was size - separated to separate into a smaller size fraction of particles less than about 11 micrometers in size and into a larger size fraction of particles larger than about 11 micrometers in size . the celatom ™ mn - 51 sample was size separated in a centrifuge , and because some particles of celatom ™ mn - 51 are non - spherical , 11 micrometers is an approximate separation size and , for example , the smaller size fraction may include elongate particles that are longer than 11 micrometers . in general herein , “ a smaller size fraction of particles less than about 11 micrometers in size ” may in some embodiments include a smaller size fraction from centrifugal size separation that may include elongate particles that are longer than 11 micrometers . the size - separated powders were examined using a philips xl - 30 scanning electron microscope after coating with evaporated gold . fig1 is a scanning electron microscope image of the smaller size fraction ( particles less than about 11 micrometers in size ) and fig2 is a scanning electron microscope image of the larger size fraction ( particles larger than about 11 micrometers in size ). the scale bar in fig1 represents 30 micrometers , whereas the scale bar in fig2 represents 120 micrometers . the original sample of celatom ™ mn - 51 was reduced in weight by about 30 % after the larger size fraction ( particles larger than about 11 micrometers in size ) was removed from it . efficacy against bedbugs of the smaller size fraction of celatom ™ mn - 51 and of the larger size fraction of celatom ™ mn - 51 was measured in three replications of eight adult common bedbugs ( cimex lectularius ) each , for a total of 24 bedbugs introduced . samples were weighed and spread on filter papers in petri dishes , and the bedbugs were then introduced . mortality assessed after 24 hours and after 48 hours . table 16 below shows the number of the initially introduced 24 bedbugs that were killed after 24 and after 48 hours when exposed to 1 , 2 , 4 , and 8 mg of the smaller size fraction of celatom ™ mn - 51 and of the larger size fraction of celatom ™ mn - 51 . from the data above , lc 50 may be calculated as shown in table 17 below . table 17 also shows confidence intervals of lc 50 in brackets where the confidence intervals were also calculated . in general , and without wishing to be bound by any theory , it is believed that diatomaceous earth may damage exoskeletons of animals having exoskeletons , which damage may lead to dehydration and death of the animals . therefore , it is believed that diatomaceous earth , and various apparatuses such as the spray apparatus 100 as described herein for example , may be effective in the control of populations of one or more of animals having exoskeletons , including arthropods , arachnids , insects , and bedbugs . herein , “ bedbugs ” may refer to common bedbugs ( cimex lectularius ), or more generally to cimex , or still more generally to cimicidae , for example . animal populations that may be controlled by diatomaceous earth in other embodiments may also include cockroaches , ants , fleas , and other pests . herein , “ control ” of an animal population may in various embodiments include prevention of growth or survival of such a population before discovery of the population , and also killing one or more members of such a population after discovery of the population . also without wishing to be bound by any theory , it is believed that diatomaceous earth may additionally or alternatively block or otherwise interfere with spiracles on exoskeletons of bedbugs , thereby diminishing or eliminating passage of air into the trachea of the bedbugs and potentially asphyxiating the bedbugs . experiment # 1 appears to indicate that lc 50 for celatom ™ mn - 51 after 48 hours is less than or comparable to lc 50 for celatom ™ mn - 53 after 96 hours . in other words , from experiment # 1 , celatom ™ mn - 51 appears to kill at least as many bedbugs in 48 hours as celatom ™ mn - 53 kills in 96 hours . also , experiment # 2 appears to indicate that lc 50 and lc 95 after 24 hours for celatom ™ mn - 51 are significantly less than lc 50 and lc 95 after 24 hours for alpine ™ dust and for pro - active ™ because the confidence intervals for those lc 50 and lc 95 values do not overlap . moreover , from experiment # 2 , celatom ™ mn - 51 appears to kill significantly more bedbugs in 24 hours than alpine ™ dust kills in 48 hours . therefore , experiment # 1 and experiment # 2 appear to indicate celatom ™ mn - 51 is more effective at killing bedbugs , and thus in controlling bedbug populations , than celatom ™ mn - 53 , alpine ™ dust , and pro - active ™. experiment # 2 appears to indicate that to lc 50 and lc 95 after 24 hours for celatom ™ mn - 51 are less than lc 50 and lc 95 after 24 hours for motherearth ™ d , but the confidence intervals for those lc 50 and lc 95 values overlap . therefore , according to experiment # 2 , celatom ™ mn - 51 may be more effective than motherearth ™ d at killing bedbugs , and thus in controlling bedbug populations , but overlap in the confidence intervals raises some uncertainty . however , experiment # 6 appears to indicate that when one bedbug contacted celatom ™ mn - 51 , that one bedbug was generally more effective at killing other bedbugs by transmitting the celatom ™ mn - 51 to the other bedbugs than was the case for motherearth ™ d . because bedbugs appear to pick up diatomaceous earth even when briefly exposed to the diatomaceous earth ( such as by crossing an area treated with celatom ™ mn - 51 as in experiment # 4 and in experiment # 5 ), because bedbugs appear to pass diatomaceous earth to other bedbugs ( see experiment # 6 and experiment # 7 ), and because celatom ™ mn - 51 appears to be more effective than motherearth ™ d in killing bedbugs by transmission of diatomaceous earth from one bedbug to other bedbugs ( see experiment # 6 ), it is believed that overall celatom ™ mn - 51 may be more effective than motherearth ™ d in controlling bedbug populations . in view of the foregoing , it is believed that celatom ™ mn - 51 may be more effective in controlling bedbug populations than the other diatomaceous earth products described above . as indicated above , different insect species have different bodies that may be affected significantly differently by different types of diatomaceous earth . without wishing to be bound by any theory , it is believed that some characteristics of celatom ™ mn - 51 may increase the effectiveness of celatom ™ mn - 51 when compared to other varieties of diatomaceous earth . for example , some characteristics of celatom ™ mn - 51 may increase the likelihood of diatomaceous earth being transmitted from one bedbug to another , thereby apparently increasing effectiveness of celatom ™ mn - 51 in controlling bedbug populations when compared to motherearth ™ d as shown in experiment # 6 . in experiment # 9 , a sample of celatom ™ mn - 51 was size separated into a smaller size fraction and into a larger size fraction , and experiment # 9 appears to indicate that the smaller size fraction was significantly more effective than the larger size fraction at killing bedbugs . fig1 illustrates fine grained , broken diatom frustules in the smaller size fraction . larger grains are absent , but there are aggregates of broken diatom frustules of , roughly , tens of micrometers . in contrast , fig2 illustrates grains that range in size from tens of micrometers to approximately 100 micrometers in length in the larger size fraction . many grains in fig2 appear not to be diatomaceous material , but rather mineral grains . therefore , experiment # 9 appears to indicate that the diatom frustules of celatom ™ mn - 51 are more effective at killing bedbugs than other components of celatom ™ mn - 51 . as shown in fig2 to 5 , some of the particles of celatom ™ mn - 51 appear to be remains of diatoms having frustules having widths less than about 3 micrometers or less than about 5 micrometers and lengths greater than about 20 micrometers or greater than about 30 micrometers . it is believed that such diatoms may be fragilaria , tabularia , or synedra , or extinct species having similar size and shape to fragilaria , tabularia , or synedra . more generally , it is believed that such diatoms may be fragilariaceae , or more generally fragilariales , or more generally fragilariophyceae , or more generally pennate diatoms , or extinct species having similar size and shape to fragilariaceae , fragilariales , fragilariophyceae , or pennate diatoms . herein , reference to “ fragilaria ”, “ tabularia ”, “ synedra ”, “ fragilariaceae ”, “ fragilariales ”, “ fragilariophyceae ”, or “ pennate ” diatoms in some embodiments may include , in addition to extant species known by such names , extinct species having similar size and shape to fragilaria , tabularia , synedra , fragilariaceae , fragilariales , fragilariophyceae , or pennate diatoms respectively . because the diatom frustules of celatom ™ mn - 51 appear to be more effective at killing bedbugs than other components of celatom ™ mn - 51 ( see experiment # 9 ), because celatom ™ mn - 51 appears to be more effective in controlling bedbug populations than the other diatomaceous earth products described above ( see experiment # 1 , experiment # 2 , and experiment # 6 ), and because celatom ™ mn - 51 appears to include one or more of remains of diatoms having frustules having widths less than about 3 micrometers or less than about 5 micrometers and lengths greater than about 20 micrometers or greater than about 30 micrometers , remains of fragilaria , remains of tabularia , remains of synedra , remains of fragilariaceae , remains of fragilariales , remains of fragilariophyceae , and remains of pennate diatoms , it is believed , without wishing to be bound by any theory , that one or more of remains of diatoms having frustules having widths less than about 3 micrometers or less than about 5 micrometers and lengths greater than about 20 micrometers or greater than about 30 micrometers , remains of fragilaria , remains of tabularia , remains of synedra , remains of fragilariaceae , remains of fragilariales , remains of fragilariophyceae , and remains of pennate diatoms may be more effective than other diatom remains at controlling bedbug populations . again without wishing to be bound by any theory , it is believed that such diatom remains may be sharper than other diatom remains and thus more likely to pierce or otherwise damage exoskeletons such as bedbug exoskeletons . also without wishing to be bound by any theory , it is believed that the size and shape of some particles in celatom ™ mn - 51 , such as one or more of remains of diatoms having frustules having widths less than about 3 micrometers or less than about 5 micrometers and lengths greater than about 20 micrometers or greater than about 30 micrometers , remains of fragilaria , remains of tabularia , remains of synedra , remains of fragilariaceae , remains of fragilariales , remains of fragilariophyceae , and remains of pennate diatoms , for example , may block or otherwise interfere with spiracles on exoskeletons of bedbugs , thereby diminishing or eliminating passage of air into the trachea of the bedbugs and potentially asphyxiating the bedbugs , more effectively than other types of diatomaceous earth . again without wishing to be bound by any theory , it is believed that in some embodiments , heat treatment or flash drying of celatom ™ mn - 51 may change the characteristics of the diatomaceous earth to be more abrasive and thus more damaging to animal exoskeletons , or more particularly to insect exoskeletons or to bedbug exoskeletons , and that such heat treatment or flash drying may also dry out the diatomaceous earth , thereby making the diatomaceous earth more absorbent to dehydrate and kill an animal or insect such as bedbug and potentially more effective in various embodiments including the various embodiments described herein . although celatom ™ mn - 51 has been discussed above , some embodiments may include alternative types of diatomaceous earth that may be supplied by other suppliers but that may include some characteristics of celatom ™ mn - 51 and that thus may have effectiveness similar to the effectiveness of celatom ™ mn - 51 . in general , such alternative types of diatomaceous earth in some embodiments may also include one or more of : remains of diatoms having frustules having widths less than about 3 micrometers or less than about 5 micrometers and lengths greater than about 20 micrometers or greater than about 30 micrometers ; remains of fragilaria ; remains of tabularia ; remains of synedra ; remains of fragilariaceae ; remains of fragilariales ; remains of fragilariophyceae ; and remains of pennate diatoms . additionally or alternatively , such alternative types of diatomaceous earth in some embodiments may be heat - treated or flash dried diatomaceous earth , such as diatomaceous earth flash dried at about 480 ° c . for about 15 seconds for example , or may more generally be modified diatomaceous earth . such alternative types of diatomaceous earth may also include other types of diatomaceous earth found in deposits formed from fresh - water diatoms , such as the deposit at clark station , nev ., united states of america for example . more generally , such alternative types of diatomaceous earth may have one or more properties similar to one or more of the properties of celatom ™ mn - 51 listed in tables 1 and 2 above in order to achieve effects that may be similar to the effects of celatom ™ mn - 51 described above . because experiment # 9 appears to indicate that the smaller size fraction was significantly more effective than the larger size fraction at killing bedbugs , alternative embodiments may include a smaller size fraction of a size - separated diatomaceous earth instead of the diatomaceous earth itself . again without wishing to be bound by any theory , it is believed that such smaller size fractions may include greater concentrations of relatively more effective diatom frustule remains . additionally or alternatively , and again without wishing to be bound by any theory , it is believed that such smaller size fractions may more relatively effectively block or otherwise interfere with spiracles on exoskeletons of bedbugs , thereby diminishing or eliminating passage of air into the trachea of the bedbugs and potentially asphyxiating the bedbugs . therefore , in various embodiments , the size - separated diatomaceous earth may include celatom ™ mn - 51 for example , and may include diatomaceous earth size - separated by centrifuge . further , in some embodiments , the smaller size fraction may include or consist of particles less than a separation size , such as about 11 micrometers for example . in embodiments where the diatomaceous earth is size separated by centrifuge , non - spherical particles may be size - separated such that the smaller size fraction may include elongate particles that are longer than the separation size . in general , size separating diatomaceous earth may prepare diatomaceous earth for use in controlling a population of insects , such as for use in the spray apparatus 100 shown in fig1 for example . experiment # 3 , experiment # 4 , and experiment # 5 appear to indicate that diatomaceous earth delivered from an aerosol product , such as the spray apparatus 100 shown in fig1 for example , is effective at killing bedbugs , and thus in controlling bedbug populations , even if the bedbugs only contact the diatomaceous earth briefly when crossing an area sprayed with diatomaceous earth ( see experiment # 4 and experiment # 5 ). in various embodiments , methods of using such an apparatus may include exposing bedbugs or other pests to diatomaceous earth , for example by spraying , propelling , or otherwise applying the diatomaceous earth to a surface . in some embodiments , when one bedbug contacts the diatomaceous earth , that bedbug may spread the diatomaceous earth to other bedbugs ( see experiment # 6 and experiment # 7 ), and therefore causing one bedbug to contact diatomaceous earth may cause death of several bedbugs . therefore , in some embodiments , spraying , propelling , or otherwise applying the diatomaceous earth to a surface where bedbugs are likely to be found may be effective even against bedbugs that do not contact the surface where the diatomaceous earth was applied . further , according to experiment # 8 , quantities of dusts deposited on filter papers weighed less than diatomaceous earth residues deposited by spraying an aerosol formulation on filter papers . again , without wishing to be bound by any theory , it is believed that perhaps diatomaceous earth delivered from an aerosol product has greater adhesiveness than a diatomaceous earth dust . the spray apparatus 100 and alternative embodiments may therefore apply diatomaceous earth to some surfaces ( such as vertical or generally vertical surfaces of furniture for example ) more durably for longer - lasting control of bedbug populations than when compared to other methods of applying diatomaceous earth to surfaces . also without wishing to be bound by any theory , it is believed that perhaps diatomaceous earth delivered from an aerosol product may be broken and reduced in size when compared to diatomaceous earth applied as a dust for example , perhaps from one or more of : crushing , such as from the ball bearing or marble 136 in response to shaking the body 102 in the embodiment shown in fig1 ; shear stress in an aerosol can ; turbulence in an aerosol can ; and relatively high velocities from a propellant in an aerosol can . further , the spray apparatus 100 and alternative embodiments may be more convenient or effective in the control of such insect populations when compared to other methods of applying diatomaceous earth to surfaces . for example , the spray apparatus 100 and alternative embodiments may advantageously apply diatomaceous earth to a surface more evenly than when compared to other methods of applying diatomaceous earth to surfaces , because the propellant may cause a generally even spray of diatomaceous earth . in some embodiments , a more even application of diatomaceous earth may increase effectiveness of the diatomaceous earth by effectively covering a greater area of a surface , and may improve the appearance of the surface by avoiding more noticeable areas of high concentration of diatomaceous earth . further , the spray apparatus 100 and alternative embodiments may enable a user to apply diatomaceous earth conveniently from a single apparatus , without having to transfer the diatomaceous earth from a container to a separate applicator apparatus as may be required in other methods of applying diatomaceous earth to surfaces . in view of the foregoing , it is believed that some embodiments of the spray apparatus 100 and alternative embodiments may effectively control populations of insects such as bedbugs . therefore , commercial use of embodiments of the spray apparatus 100 and of alternative embodiments may involve distributing , selling , offering for sale , placing , or otherwise using such spray apparatuses in an effort to control populations of animals , such as animals having exoskeletons , arthropods , arachnids , insects , and bedbugs for example . pct international patent application no . pct / ca2012 / 000389 filed at the canadian receiving office of the pct on apr . 26 , 2012 describes and illustrates various furniture apparatuses such as a nightstand , a dresser , a bed , a mattress , and a headboard that may include one or more substantially thermoplastic bodies including diatomaceous earth , legume extracts , or both incorporated therein , and such furniture apparatuses according to some embodiments may assist in the control of bedbug and other insect populations . therefore , commercial use of embodiments of the spray apparatus 100 and of alternative embodiments may also involve distributing , selling , offering for sale , placing , or otherwise using such spray apparatuses together with such furniture apparatuses in an effort to control populations of animals , such as animals having exoskeletons , arthropods , arachnids , insects , and bedbugs for example . as indicated in pct international patent application no . pct / ca2012 / 000389 filed at the canadian receiving office of the pct on apr . 26 , 2012 , in some embodiments of furniture apparatuses , one or more internal surfaces may be darkly coloured , such as coloured black or another dark colour . thus , for example when diatomaceous earth is applied to such internal surfaces with an embodiment of the spray apparatus 100 or an alternative embodiment , the lighter colour of the diatomaceous earth may make the diatomaceous earth more easily visible on such surfaces , and may facilitate noticing an absence of such products on such surfaces . therefore , such darkly coloured internal surfaces in some embodiments may assist with visibly determining whether such internal surfaces have been sprayed or otherwise treated with diatomaceous earth or another more lightly coloured product , and such visual determinations may facilitate determining where and when such diatomaceous earth or other products should be applied to ensure a desired amount of such diatomaceous earth or other products on various furniture apparatuses . more generally , an embodiment of the spray apparatus 100 shown in fig1 or an alternative embodiment may facilitate applying diatomaceous earth to surfaces where bedbugs may be introduced into a room , such as a bed , dresser , or side table where bedbugs may be introduced by occupants or from belongs of occupants of a room , or other surfaces where bedbugs may be likely to travel . diatomaceous earth is a natural product , and in some embodiments , natural products may be preferable over other pest control products , such as synthetic pesticides for example , because natural products may be less harmful to humans , to other life , or more generally to the environment . in view of the foregoing , the spray apparatus 100 shown in fig1 and alternative embodiments may be advantageous when compared to other methods of controlling bedbug and other insect populations . although specific embodiments have been described and illustrated , such embodiments should be considered illustrative only and not as limiting the invention as construed in accordance with the accompanying claims .