drywood termites cause significant damage to wood in structures in the united states , with two species , incisitermes minor ( hagen ) and cryptotermes brevis ( walker ) , being responsible for the majority of damage ( su and scheffrahn , 1990 ; grace , 2009 ) .
the economic cost of control and repair of damage is second only to that for subterranean termites ( su and scheffrahn , 1990 ) .
remedial control of drywood termites in the united states relies primarily on either ( 1 ) fumigation of the entire structure with a toxic gas or heated air , or ( 2 ) localized chemical or physical treatments designed to eradicate small , localized colonies ( lewis and haverty , 1996 ; lewis , 2008 ; lewis and rust , 2009 ) .
fumigation treatments are likely to kill all of the termites in a structure , while localized treatments can destroy all termites in a colony , provided the treatment is delivered to the entire gallery system .
the size , number , and dispersion of drywood termite colonies in a structure can vary greatly , depending on the age of the infestation and the success of preventative or remedial treatments .
drywood termite colonies also are considered single piece nesters , i.e. , they nest within their food source and do not forage from the nesting site to a food source ( abe , 1987 ) .
in fact , large , dispersed colonies ( or even small colonies ) can live in a single piece of wood or in multiple pieces of wood that are joined together ( grace et al . ,
drywood termites are cryptic , seldom leaving obvious or visible external signs of their presence in wood . a commonly used sign for determining the presence of drywood termites is the occurrence of fecal pellets , ejected through a  kick - out hole  in the external surface of wood from the internal galleries ( ebeling , 1975 ) .
these pellets often are found as conical piles or are scattered on horizontal surfaces below infested wood .
these hexagonally sided pellets are diagnostic for drywood termites , and can be used to distinguish damage from that by other wood - destroying insects ( ebeling , 1975 ; moore , 1992 ) .
grace and yamamoto ( 2009 ) demonstrated the relationship between the cellulose and lignin content of the food utilized by small groups of c. brevis and incisitermes immigrans ( light ) , and the quantity of fecal pellets produced over time .
they also discussed the use of the size and number of fecal pellets for estimating both size and age of drywood termite colonies .
drywood termites excrete feces in the form of hard , even - shaped fecal pellets .
these fecal pellets contain the same mixture of hydrocarbons as the insects that produced them , albeit in slightly different proportions ( haverty et al .
, 2005 ) . because cuticular hydrocarbons are species specific in termites ( page et al . , 2002 )
rather than simply signaling the general presence of termites or providing a diagnosis of the species of termite inhabiting the wood , we postulated that these pellets could be chemically characterized so as to determine the status of a colony as active ( alive ) or inactive ( dead ) . here , we report quantification of the hydrocarbons in pellets of i. minor aged for up to 1  year after they were produced .
we document the changes in proportions of selected hydrocarbons as an indication of the length of time since the pellets were excreted .
collection of termites and preparation of termite containment unit termites , i. minor , were removed from one naturally infested board ( 98.9    13.3    271.8  cm ) collected on 19 july 2006 from lakeview , california , and stored at the university of california richmond field station .
the board was cut across the grain into pieces , 58  cm thick , and stored at room temperature .
a wood chisel was used to separate pieces of wood into smaller pieces , 0.51.0  cm thick .
all remaining live termites , including soldiers and primary reproductives ( alates ) , were placed in a termite containment unit ( tcu ) .
termites thus collected were likely from a large mixed colony ( booth et al . , 2010 ) or from multiple colonies .
we were not able to assign the various galleries in the wood to any particular colony.fifteen birch tongue depressors were bundled together , and three equally spaced holes drilled across the length of the bundle using a 2.8-mm bit .
bamboo skewers , 1013  cm in length , were inserted into each of the three holes in the bundle of tongue depressors .
spaces , 36  mm , were left between each tongue depressor allowing termites access to all tongue depressors .
two sets of skewered tongue depressors were placed into a clean plastic container ( 17.5    12.5    6  cm ) , one on top of the other , such that the tongue depressors on the top layer fit into the gaps created by the tongue depressors on the bottom layer .
tongue depressors were lightly misted with water , and then 6,662 drywood termites ( a mixture of pseudergates or workers , alates , and soldiers ) were placed in the tcu .
tcus , with termites , were maintained in a dark cabinet in the laboratory under ambient conditions prior to collection of fecal pellets .
a single colony or a mixture of two or more colonies , representing a single location within california , was prepared in this manner . pellet collection and aging process
after all the tcus had acclimated to laboratory conditions over several weeks , new holding chambers were prepared .
all wood debris , pellets , dead termites , and damaged tongue depressors were discarded .
the termites in the new holding chambers were maintained in the laboratory under ambient conditions for 2  weeks . at the end of this period
, all pellets were removed , and sub - samples collected and readied for the aging study .
concurrently , three samples of 20 workers , three samples of 20 alates , and one sample of 20 soldiers were also collected for hydrocarbon analysis .
live termites were placed in a 20-ml scintillation vial and frozen until extraction.fecal pellets were separated from debris by sequentially sifting them through successively smaller sieves ( haverty et al . , 2005 ) .
thus , all substances such as hand lotion , lip balm , parafilm , and waxed paper were kept away from the work area .
gloves were worn when handling pellets , and implements that came in contact with pellets were wiped with a paper towel dampened with absolute ethanol to remove any oils or waxes .
pellets were separated from fine debris by removing individual pellets with forceps or with an aspirator , until a sample weighing approximately 200  mg was obtained.in developing this protocol we made one estimate and one critical assumption .
the estimate was that at least 1,000 pellets were needed for each hydrocarbon analysis ( based on preliminary analyses of pellets collected from drywood termites maintained in our laboratory ) .
( 1997 ) using c. brevis and i. snyderi ( light ) from southern florida . in that study , 40 i. snyderi ( pseudergates or workers ) produced 573 pellets over 4  weeks , slightly less than 150 pellets / wk or about 3.5 pellets / individual / wk . in a study with small groups of c. brevis and i. immigrans , grace and yamamoto ( 2009 ) found that these species produced 4.9 to 7.0 pellets / individual / wk . for our study , we assumed that i. minor would produce pellets at roughly the same rate and , therefore , we needed about 3,000 to 5,000 individuals in a tcu for this study .
we prepared one tcu to collect the requisite quantity of fecal pellets.four sub - sampling intervals , each replicated three times , were used : 0 , 30 , 90 , and 365  days from the initial collection date .
sub - samples were stored in clean , 20-ml scintillation vials , sealed with 1.5    1.5  mm mesh screen .
vials were stored in a dark cabinet at the university of california richmond field station at ambient temperature.voucher samples of i. minor pseudergates or workers and soldiers from this study ( fresh , not dried ) were preserved in 85% ethanol and deposited in the essig museum , university of california at berkeley ( haverty et al . ,
extraction procedure and characterization of hydrocarbons hydrocarbons from workers , alates , soldiers , and fecal pellets of i. minor were extracted , characterized , and quantified as previously reported ( haverty et al . , 2005 ) .
frozen termite samples were thawed and dried at 70c for approximately 1  h before extraction . each sub - sample of fecal pellets or termites
was placed in a 20-ml scintillation vial , and immersed in 10  ml of n - hexane for 10  min . after extraction
, hydrocarbons were separated from other compounds through 4  cm of activated sigma silica gel ( 70230 mesh ) in pasteur pipette mini - columns .
the resulting hydrocarbon fractions were evaporated to dryness under a stream of nitrogen and redissolved in 60 l of n - hexane for gas chromatography - mass spectrometry ( gc - ms ) analysis .
a 3-l aliquot was injected into the gc-ms.gc-ms analyses were performed on an agilent 6890 gas chromatograph interfaced with an agilent 5973 mass selective detector , using agilent chemstation data analysis software ( g1701ca version c.00.00 ) .
the gc - ms was equipped with an hp-1ms , fused silica capillary column ( 30  m    0.25  mm i.d , 0.25  m film thickness ) , and was operated in split mode ( split ratio of 30:1 ) , using helium as carrier gas .
the column oven was programmed from 200320c at 3c  min , with a final hold of 11  min .
electron impact ( ei ) mass spectra were obtained at 70  ev.all chemicals of interest were identified by their retention times and mass spectra .
mass spectra of methyl - branched alkanes were interpreted as described by blomquist et al .
olefins were identified by their mass spectra , although double bond positions were not determined ( haverty et al . , 2005).in the text , tables , and figures , we use shorthand nomenclature to identify individual hydrocarbons or mixtures of hydrocarbons .
this shorthand uses a descriptor for the location of methyl groups ( x - me ) , the total number of carbons ( cxx ) in the hydrocarbon component excluding the methyl branch(es ) , and the number of double bonds following a colon ( cxx : y ) .
thus , pentacosane is represented as n - c25 , 11-methylnonacosane as 11-mec29 , 13,17-dimethylhentriacontane as 13,17-dimec31 , and heptatriacontatriene as c37:3 .
hydrocarbons are presented in the tables for each caste and worker fecal pellets in the order of elution from our gc - ms system .
statistical analysis gc - ms peak ( some peaks contained more than one compound or a mixture of positional isomers ) areas were converted to percentages of total hydrocarbon fraction , enabling mean ( sd ) relative amounts of each hydrocarbon peak for workers and alates , and overall mean ( sd ) of each hydrocarbon peak for the fecal pellets , to be calculated.the percentage of each hydrocarbon peak for pellets of each aging period was transformed to the log of the percentage ( dependent variable y ) and regressed against the days of aging ( independent variable x ) .
hydrocarbons with slopes different from 0 (   =  0.05 ) were separated into two groups : those with a significant positive slope and those with a significant negative slope . for each aging period ( 0 , 30 , 90 , and 365  day ) , an index of age ( iage ) was created by subtracting the sum of the percentages of the hydrocarbons with a negative slope over time from the sum of the percentages of the hydrocarbons with a positive slope over time [ iage  =   ( peakpositive ) minus  ( peaknegative ) , for each aging period ] .
the iage for each aging period then was regressed against the aging period ( r development core team , 2004 ) .
the cuticular hydrocarbons for i. minor pseudergates and fecal pellets were characterized previously ( haverty et al . , 2000 , 2005 ) .
the composition of the hydrocarbon mixture for this species and the hydrocarbons from their fecal pellets in the present study are displayed in fig . 
1total ion chromatogram of cuticular hydrocarbons from a workers of incisitermes minor ( hagen ) and b from fecal pellets from the same collection .
acronyms for hydrocarbons are derived as follows : x - me location of methyl groups , the total number of carbons cxx in the hydrocarbon component excluding the methyl branch(es ) , and cxx : y the number of double bonds following a colontable  1relative abundance of hydrocarbons from pseudergates , alates , soldiers , and fecal pellets of incisitermes minor ( hagen)hydrocarbonspseudergates n  =  3alates n  =  3soldiers n  =  1fecal pellets n  =  122-mec220.06 ( 0.02)0.08 ( 0.02)0.090.11 ( 0.02)n - c231.30 ( 0.06)1.34 ( 0.05)1.481.35 ( 0.18)2-mec231.45 ( 0.40)1.72 ( 0.35)2.112.13 ( 0.28)3-mec231.31 ( 0.38)1.38 ( 0.30)1.712.06 ( 0.29)n - c240.46 ( 0.01)0.43 ( 0.02)0.480.32 ( 0.05)2-mec240.13 ( 0.03)0.19 ( 0.03)0.190.15 ( 0.02)3-mec240.08 ( 0.02)0.10 ( 0.02)0.120.11 ( 0.02)n - c2516.35 ( 0.16)11.75 ( 0.40)12.648.65 ( 1.05)2-mec250.18 ( 0.01)0.27 ( 0.01)0.240.14 ( 0.02)3-mec250.23 ( 0.04)0.36 ( 0.04)0.340.26 ( 0.03)n - c262.25 ( 0.15)1.17 ( 0.07)1.510.87 ( 0.12)2-mec260.14 ( 0.01)0.13 ( 0.01)0.140.07 ( 0.01)n - c2714.04 ( 0.55)6.81 ( 0.31)10.055.91 ( 0.65)2-mec270.13 ( 0.01)0.09 ( 0.01)0.130.06 ( 0.01)3-mec270.20 ( 0.01)0.19 ( 0.01)0.250.12 ( 0.01)n - c280.43 ( 0.05)0.17 ( 0.01)0.350.15 ( 0.03)n - c293.38 ( 0.33)1.27 ( 0.07)2.971.38 ( 0.18)11-mec290.06 ( 0.01)0.15 ( 0.01)0.100.09 ( 0.01)9,13-dimec290.70 ( 0.02)0.82 ( 0.01)0.910.63 ( 0.06)9,13,17-trimec290.11 ( 0.02)0.27 ( 0.00)0.160.22 ( 0.03)n - c300.04 ( 0.00)0.07 ( 0.00)0.100.0013-mec300.01 ( 0.02)0.08 ( 0.00)0.040.0010,14-dimec300.64 ( 0.06)1.45 ( 0.02)0.880.90 ( 0.03)10,14,18-trimec300.18 ( 0.02)0.43 ( 0.01)0.240.28 ( 0.02)n - c310.14 ( 0.01)0.10 ( 0.01)0.200.09 ( 0.01)15- ; 13- ; 11- ; 9-mec310.36 ( 0.03)0.82 ( 0.01)0.420.49 ( 0.02)13,17- ; 11,15-dimec317.45 ( 0.68)13.74 ( 0.52)8.5510.67 ( 1.80)9,13,17-trimec310.57 ( 0.05)1.19 ( 0.02)0.720.89 ( 0.06)7,11,15-trimec310.54 ( 0.04)0.99 ( 0.01)0.720.81 ( 0.09)14- ; 12-mec320.17 ( 0.01)0.33 ( 0.02)0.190.27 ( 0.03)12,16-dimec322.01 ( 0.14)3.57 ( 0.05)2.222.97 ( 0.28)10,14,18- ; 8,12,16-trimec320.46 ( 0.03)0.80 ( 0.02)0.610.82 ( 0.06)15- ; 13-mec330.93 ( 0.05)1.57 ( 0.03)0.921.30 ( 0.08)13,17- ; 11,15- ; 9,13-dimec334.63 ( 0.31)6.87 ( 0.11)5.117.41 ( 1.03)9,13,17-trimec331.30 ( 0.08)2.02 ( 0.02)1.863.47 ( 0.33)7,13,17-trimec330.21 ( 0.02)0.32 ( 0.01)0.320.47 ( 0.07)c35:31.01 ( 0.03)2.93 ( 0.17)1.641.76 ( 0.17)c35:22.31 ( 0.06)4.46 ( 0.14)2.713.55 ( 0.15)12,16-dimec34 ; c35:10.68 ( 0.02)1.16 ( 0.03)0.851.40 ( 0.10)10,14,18- ; 8,12,16-trimec340.28 ( 0.00)0.50 ( 0.04)0.450.89 ( 0.14)15- ; 13- ; 11-mec350.56 ( 0.02)0.85 ( 0.05)0.671.11 ( 0.09)13,17-dimec351.27 ( 0.09)1.96 ( 0.02)1.833.95 ( 0.46)9,13,17-trimec350.14 ( 0.01)0.28 ( 0.03)0.270.93 ( 0.14)c37:31.74 ( 0.06)3.33 ( 0.16)2.723.28 ( 0.34)c37:21.67 ( 0.06)2.55 ( 0.08)2.182.90 ( 0.10)12,16-dimec360.17 ( 0.01)0.34 ( 0.02)0.280.71 ( 0.08)c37:10.78 ( 0.02)0.76 ( 0.03)0.810.83 ( 0.06)10,14,18-trimec36 ; c37:10.44 ( 0.03)0.35 ( 0.05)0.430.58 ( 0.10)13 ; 11-mec370.71 ( 0.01)0.60 ( 0.04)0.770.89 ( 0.14)13,17- ; 11,15-dimec370.87 ( 0.05)1.27 ( 0.01)1.252.13 ( 0.22)9,13,17-trimec370.09 ( 0.01)0.13 ( 0.01)0.130.30 ( 0.06)c39:30.09 ( 0.02)0.18 ( 0.02)0.290.49 ( 0.16)c39:3 ; 12-mec380.49 ( 0.04)0.56 ( 0.03)0.761.03 ( 0.18)14,18 ; 12,16-dimec380.02 ( 0.03)0.14 ( 0.01)0.140.24 ( 0.04)c39:1 ; 10,14,18-trimec382.73 ( 0.19)1.73 ( 0.04)2.531.74 ( 0.23)13- ; 11-mec391.75 ( 0.09)1.03 ( 0.03)1.701.26 ( 0.20)13,17- ; 11,15-dimec390.90 ( 0.01)1.04 ( 0.14)1.361.44 ( 0.08)9,13,17-trimec390.41 ( 0.03)0.17 ( 0.09)0.110.20 ( 0.03)12- ; 10-mec400.38 ( 0.05)0.20 ( 0.01)0.350.26 ( 0.07)12,16-dimec400.27 ( 0.00)0.27 ( 0.02)0.340.32 ( 0.05)c41:13.31 ( 0.27)1.70 ( 0.04)2.791.58 ( 0.25)13- ; 11-mec412.78 ( 0.20)1.45 ( 0.06)2.591.74 ( 0.31)13,17- ; 11,15-dimec413.34 ( 0.13)2.90 ( 0.15)4.003.33 ( 0.19)9,13,17-trimec410.79 ( 0.02)0.30 ( 0.02)0.330.42 ( 0.19)12- ; 10-mec420.30 ( 0.03)0.15 ( 0.01)0.250.26 ( 0.27)12,16-dimec420.48 ( 0.04)0.37 ( 0.02)0.520.47 ( 0.12)c43:12.72 ( 0.28)1.25 ( 0.06)2.271.31 ( 0.26)15- ; 13-mec431.00 ( 0.14)0.46 ( 0.05)0.870.61 ( 0.16)13,17-dimec431.99 ( 0.16)1.18 ( 0.16)1.931.68 ( 0.28)14,18-dimec440.12 ( 0.02)0.07 ( 0.01)0.120.13 ( 0.06)c45:10.42 ( 0.09)0.16 ( 0.02)0.330.21 ( 0.07)13-mec450.000.000.000.04 ( 0.03)13,17-dimec450.37 ( 0.08)0.18 ( 0.02)0.340.43 ( 0.13)mean percent ( sd ) of total hydrocarbon composition
. compounds are listed in elution orderacronyms for hydrocarbons are derived as follows : location of methyl groups ( x - me ) , the total number of carbons ( cxx ) in the hydrocarbon component excluding the methyl branch(es ) , and the number of double bonds following a colon ( cxx : y)these hydrocarbons were not reported for i. minor pseudergates or fecal pellets in haverty et al .
( 2005)an isomeric mixture or two or more compounds co - eluted in this peak total ion chromatogram of cuticular hydrocarbons from a workers of incisitermes minor ( hagen ) and b from fecal pellets from the same collection .
acronyms for hydrocarbons are derived as follows : x - me location of methyl groups , the total number of carbons cxx in the hydrocarbon component excluding the methyl branch(es ) , and cxx : y the number of double bonds following a colon relative abundance of hydrocarbons from pseudergates , alates , soldiers , and fecal pellets of incisitermes minor ( hagen ) mean percent ( sd ) of total hydrocarbon composition .
compounds are listed in elution order acronyms for hydrocarbons are derived as follows : location of methyl groups ( x - me ) , the total number of carbons ( cxx ) in the hydrocarbon component excluding the methyl branch(es ) , and the number of double bonds following a colon ( cxx : y ) these hydrocarbons were not reported for i. minor pseudergates or fecal pellets in haverty et al .
( 2005 ) an isomeric mixture or two or more compounds co - eluted in this peak hydrocarbons from termites
n - alkanes and dimethylalkanes were the predominant classes of hydrocarbons in all castes and in fecal pellets ( table  2 ) , as previously reported by haverty et al .
n - alkanes comprised from 23.12% to 38.39% , unsaturated components from 15.21% to 19.03% , terminally branched monomethylalkanes from 3.90% to 5.32% , internally branched monomethylalkanes from 7.70% to 9.01% , and dimethylalkanes from 25.25% to 36.18% , of the total hydrocarbon content .
there was also a homologous series of trimethylalkanes , representing 8.26% to 9.48% of the total hydrocarbon content . 

table  2relative abundance of hydrocarbon classes from pseudergates , alates , soldiers , and fecal pellets of incisitermes minor ( hagen)hydrocarbon classpseudergatesalatessoldiersfecal pelletsnormal alkanes38.3923.1229.7718.71olefins18.3821.1120.3120.66terminally branched methylalkanes3.904.495.325.19internally branched methylalkanes9.017.708.888.33dimethylalkanes25.2436.1829.7937.40trimethylalkanes5.097.405.929.71percent of total hydrocarbon compositionall peaks with co - eluting olefins and saturated compounds are summarized as olefinsthe hydrocarbons of i. minor characterized in this study included all of the compounds reported by haverty et al .
( 2005 ) , as well as 18 additional hydrocarbons ( table  1 ) .
these additional hydrocarbons were not abundant , never representing more than 0.85% of the total hydrocarbon ( as for the mixture of 12,16-dimec34 and c35:1 in soldiers ) content , and usually much less .
the detection of these additional hydrocarbons in this study are likely due to the greater concentration of the extracted hydrocarbons used or , possibly , colony to colony variation .
relative abundance of hydrocarbon classes from pseudergates , alates , soldiers , and fecal pellets of incisitermes minor ( hagen ) percent of total hydrocarbon composition all peaks with co - eluting olefins and saturated compounds are summarized as olefins hydrocarbons from termite fecal pellets in general , the hydrocarbons from whole - body extracts of i. minor were represented in extracts of fecal pellets . as with whole - body extracts of i. minor , dimethylalkanes were the predominant class of hydrocarbon , followed by olefins and normal alkanes ( table  2 ) .
1 ) were found in termites and not in fecal pellets , but these were present in small quantities , less than 0.1% of the total hydrocarbon content .
the lack of these two hydrocarbons in fecal pellets may be a function simply of the concentration of the extracts .
changes in hydrocarbons of fecal pellets over time we identified 73 hydrocarbon peaks in fecal pellets of i. minor ( table  1 ) . of these peaks
( data from non - significant slopes not reported ) , 19 of 73 ( 26% ) had a significant change , either positive ( five ) or negative ( 14 ) , over time ( fig .  2 ) .
this is a much higher number of statistically significant slopes ( different from 0 ) , than would be expected by chance alone ( 5% of 73 peaks is < 4 peaks ) . 

2changes in percent content of individual hydrocarbons , over time , from fecal pellets of incisitermes minor workers . a hydrocarbons with significant (   =  0.05 ) negative slopes , and b hydrocarbons with significant positive slopes .
acronyms for hydrocarbons are derived as follows : x - me location of methyl groups , the total number of carbons , cxx in the hydrocarbon component excluding the methyl branch(es ) , and cxx : y the number of double bonds following a colonthe index , iage , for each of the three replications ( a , b , and c at 0 , 30 , 90 , and 365  day ) was plotted against the associated number of days ( fig . 
the fitted line , with a 95% confidence interval for the means to show the variability of the replicates , had a high adjusted r (= 0.888 ) value , suggesting that it might be possible to predict fecal age by the index . 

3fitted line and 95% confidence intervals for a plot of the mean of index of age ( iage ) against age .
values for 30  day are jittered a small amount so that all three data points can be seen changes in percent content of individual hydrocarbons , over time , from fecal pellets of incisitermes minor workers . a hydrocarbons with significant (   =  0.05 ) negative slopes , and b hydrocarbons with significant positive slopes .
acronyms for hydrocarbons are derived as follows : x - me location of methyl groups , the total number of carbons , cxx in the hydrocarbon component excluding the methyl branch(es ) , and cxx : y the number of double bonds following a colon fitted line and 95% confidence intervals for a plot of the mean of index of age ( iage ) against age .
values for 30  day are jittered a small amount so that all three data points can be seen we do not know the basis by which peaks increase or decrease over the 1-year period .
in general , those that increased in relative abundance tended to have higher initial relative abundances ; i.e. , mono- , di- , or tri - methylalkanes with carbon chains of 31 , 32 , or 33 .
those that decreased were represented in five of the six classes of hydrocarbons , ranging from c26 to c45 .
the composition of the hydrocarbon mixture of insects is genetically controlled ( toolson and kuper - simbrn , 1989 ; kaib et al . , 1991 ; page et al . , 1991 ; coyne et al . , 1994 ) .
this composition can be slightly affected by diet and environmental conditions ( hadley , 1977 ; espelie et al . , 1994 ; chapman et al . , 1995
( 1996 ) demonstrated significant seasonal variation in quantities of some hydrocarbons of coptotermes formosanus shiraki from hawaii ; these differences were small and associated with the production of alates .
however , the qualitative mix of hydrocarbons has been shown to be stable over decades among species of cone beetles in the genus conophthorus ( page et al . , 1990 ) .
the motivation for our study was to devise a method for the evaluation of the success or failure of drywood termite treatments , including fumigation and local application methods .
with the recent classification of sulfuryl fluoride ( the only fumigant active ingredient registered in california ) as a greenhouse gas ( mhle et al . , 2009 ) and
the anticipated increase in local treatments , we felt that there would be considerable interest by the industry , regulatory agencies , and consumers for a simple and accurate means to determine whether or not a targeted colony / infestation is still in a structure .
our method , based on changes in hydrocarbon chemistry over time , shows promise to this end .
future research includes : ( 1 ) validating these findings for additional species of drywood termites and geographic populations of the same species , ( 2 ) validating these findings at different times of the year , and ( 3 ) exploring seasonality in pellet production and hydrocarbon quality in pellets .
 hydrocarbon mixtures extracted from fecal pellets of drywood termites are species - specific and can be characterized to identify the termites responsible for damage , even when termites are no longer present or are unable to be recovered easily . in structures infested by drywood termites , it is common to find fecal pellets , but difficult to sample termites from the wood . when fecal pellets appear after remedial treatment of a structure , it is difficult to determine whether this indicates that termites in the structure are still alive and active or not . 
 we examined the hydrocarbon composition of workers , alates , and soldiers of incisitermes minor ( hagen ) ( family kalotermitidae ) and of fecal pellets of workers . 
 hydrocarbons were qualitatively similar among castes and pellets . 
 fecal pellets that were aged for periods of 0 , 30 , 90 , and 365  days after collection were qualitatively similar across all time periods , however , the relative quantities of certain individual hydrocarbons changed over time , with 19 of the 73 hydrocarbon peaks relatively increasing or decreasing . 
 when the sums of the positive and negative slopes of these 19 hydrocarbons were indexed , they produced a highly significant linear correlation ( r2  =  0.89 ) . 
 consequently , the quantitative differences of these hydrocarbons peaks can be used to determine the age of worker fecal pellets , and thus help determine whether the colony that produced them is alive or dead . 
Introduction
Methods and Materials
Results and Discussion