Wednesday, August 21, 2013


The Mantis (praying mantis) is an effective predator and usually a welcome insect in organic gardening. There are many species of mantis in temperate and tropical climates worldwide.

The mantis is able to see up to 20 meters and has precise stereoscopic vision up close. They possess the unique ability to turn their heads 180º, and use this ability to determine the relative distance of their prey. They wait motionless, relying on camouflage to conceal their presence while other insects wander close enough to reach. They strike within 30 to 50 thousandths of a second with incredible accuracy, and can even snatch flies and mosquitoes from the air. They hold their prey in their barbed forelimbs while they eat them alive. Mantids sometimes prey on animals much larger than themselves.

Mantids usually fly at night, when they are least vulnerable to natural predators like birds. They can hear and avoid the echolocation sounds made by bats. They are non-venomous and have no chemical defenses to discourage other animals from eating them.

Whether the mantis is useful in gardens depends on the intention of the gardener. Mantids prey on any insect they can catch including beneficial insects and other mantids. The common belief that a female mantis will devour her mate is a habit most often observed in captivity when the female is hungry. In the wild, males are very cautious around hungry females.

The mantis is most closely related to roaches and termites. They lay eggs in clusters of 10 to 400 eggs that are available for purchase at garden supply stores. Mantis nymphs, emerging from eggs look similar to adult mantids and often mimic ants. If prey is not immediately available, the nymphs will cannibalize each other. The typical life span of a mantis is 10 to 12 months.

Mantis on a papaya. Photo credit Nate Porter.


Thursday, August 15, 2013


Phosphorus is an essential macro-nutrient for plants and all life on earth. Phosphorus is a component of nucleic acids, ATP and the phospholipid bi-layer that encloses cells.

Phosphorus is a scarce finite resource on planet earth. It is extracted from phosphate rock almost entirely for agriculture use around the world. There are organic and synthetic processes of phosphate extraction in mineral mining.



Phosphoric acid is often used in hydroponics to bring the pH of a nutrient solution down.
Plant Nutrition Facts
Phosphorus (P)
Absorbable Forms H2PO4- and HPO42-
Fertilizers Phosphoric acids, super-phosphate, ammonium phosphate, phosphogypsum, apatite, animal waste, bone meal, algae
Symptoms of Deficiency Plant is dark green with purple veins and stunted; burned leaf tips
Necessary in the synthesis of ATP, phospholipids in cell walls and nucleic acids. Promotes growth of roots and shoots.
Plant Nutrition
Phosphorus is necessary during all stages of plant growth. Plants need more phosphorus during periods of advanced expression: blooming and fruiting.
Synthetic: Extracted from phosphate rock using synthetic chelates that appear in trace amounts in non-organic produce.

Organic: (1)Extracted from phosphate rock using organic chelates like humic acids. Identical to phosphates naturally occuring in soil. (2)Recovered from bone meal, guanos, urine or algae.
Adverse Effects
Mineral sources of phosphorous may contain trace amounts of toxic heavy metals like cadmium, flouride, uranium, radium or polonium. Synthetic phosphates contain trace amounts of synthetic chelates. Phosphate fertilizers leaching into aquatic environments promote algae blooms that kill fish. Flourine, as a component of super-phosphates, contributes to soil sterilization.

Tuesday, August 13, 2013

Lady Beetles

Beetles of the family Coccinellidae called Lady Beetles, or Lady Bugs in most of North America, are important insects worldwide. Lady beetles are a favorite insect in cultures on every continent. These beetles have often appeared in old stories, poems and children’s literature possessing virtues associated with good nature and luck. For gardeners they provide effective pest-control of aphids and other harmful insects.

Lady beetles and their larvae prey on aphids and scales. Some species even prey on caterpillars or spider mites.  

The lady beetle lays eggs near their prey that hatch in 5 - 7 days. The larvae emerge with six prominent legs on the upper torso and a distinct lady-beetle head and mouthparts. The larval period lasts around 2 weeks then larvae find a spot to fix themselves for pupation and begin the transformation to an adult lady beetle. The pupation stage lasts 5 to 8 days before the beetle emerges with a soft and less-colorful exoskeleton that will become more colorful as it hardens.

Lady beetle larvae on chamomile
Lady beetle pupae

An adult lady beetle will live 1 to 2 years. Within a year they can have as many as three generations of offspring. They find a warm and protected place to enter dormancy during the winter. This is the reason lady beetles begin to invade homes in the late autumn. Most lady beetles for-purchase from a garden supply store, nursery or online are collected from one species that aggregate for winter in higher-elevation areas of California. 

Lady beetles produce an alkaloid toxin giving them an acrid taste to predators. Their flashy red coloring serves as a reminder to predators not to eat them. Lady beetles may also “reflex bleed” when physically disturbed and force the toxin out from their joints as an appetite-deterrent. The term “ladybird taint” refers to the flavor of wine when ladybird beetles have found their way into the process.

The harlequin lady beetle from Asia was established in the United States in 1988 for aphid control, and has since spread to most of the United States and Western Europe. This species has displaced many native populations of lady beetles, but is uniquely effective against soybean aphids, another invasive species from Asia.

Lady beetles may occasionally bite people. Although the bite is described as only mildly irritating, it can cause some people to have an allergic reaction.

Introducing lady beetles into your garden will more than likely benefit your neighbors. Lady beetles tend to disperse when released. They are not likely to reproduce for weeks while they feed and recover from the stress of relocation. Keeping one plant with aphids in a location away from the garden may improve the likelihood of keeping lady beetles in the area. Lady beetles are compatible with many natural pest-deterrents like soaps, neem and herbal oils.

Original photos by Nate Porter.


Wednesday, August 7, 2013


Nitrogen (N) is one of the essential building blocks of nucleotides for DNA and RNA and of amino acids for proteins. Nitrogen is necessary for all of life on earth. For plants, nitrogen is the limiting factor for growth and the primary ingredient in fertilizer. Plant’s can only absorb nitrogen as ammonia (NH3) or as nitrate (NO3). These molecules are relatively scarce compared to atmospheric nitrogen (N2) that makes up 78.09% of earth’s atmosphere. 

Before 1913, all of the nitrogen in plants and animals was produced by organic bacteria with special enzymes that convert atmospheric nitrogen to absorbable forms. Today more than half of the nitrogen in our bodies was produced industrially from fossil fuels using a synthetic process of Nitrogen fixation. Industrial nitrogen fertilizers are a major source of environmental pollution.

The nitrifying reactions of bacteria
Atmospheric nitrogen to ammonia:
N2 + 8H+ + 8e- => 2NH3 + H2
Ammonia to nitrite by Nitrosomonas bacteria:
2NH3 + 3O2 => 2NO2 + 2H+ + 2H2O
Nitrite to nitrate by Nitrobacter bacteria:
2NO2- + O2 => 2NO3-
Ammonia is the first product of nitrogen fixation by bacteria called diazotrophs using the enzyme nitrogenase. These bacteria are abundant in low-oxygen environments like soil, mud and decomposing organic materials. Urea, a component of animal urine is also metabolized by bacteria with the enzyme urease to produce ammonia. Ammonia is a weak base and reacts with acids to form ammonium (NH4+) salts. The ammonium ion in water is readily available for absorption by plants.

Nitrosomonas bacteria convert ammonia to nitrite, which is not a form of nitrogen available to plants. Nitrobacter bacteria convert nitrite to nitrate which is available to plants.
Plant Nutrition Facts
Nitrogen (N)
Absorbable Forms Nitrate (NO3-) and Ammonium (NH4+)
Fertilizers ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, urea
Symptoms of Deficiency Oldest leaves turn yellow and die prematurely; plant is stunted
Necessary for the synthesis of proteins and nucleic acids. Nitrogen is the limiting factor of vegatation and growth.
Plant Nutrition
Plants need nitrogen throughout the grow cycle. Plants use more nitrogen during the vegetative stage to grow and produce leaves. Plants use less nitrogen when flowering and fruiting.
Synthetic: The major source of industrial nitrogen fertilizer is anhydrous ammonia: a chemical gas most abundantly derived from non-renewable fossil fuels.

Organic: Nitrogen is made available organically through decomposition by nitrogen-fixing bacteria in soil. Organic fertilizers use natural sources for nitrogen like animal waste or composted materials.


Monday, August 5, 2013


Aphids are despised by farmers in temperate climates worldwide and for obvious reasons. Aphids will reproduce quickly on certain plants until the stem and leaves are covered in these plump squishy insects. They feed by piercing a plant with sharp mouth parts and sucking sugar-rich fluid from the phloem where sugars are transported. Not only does this starve the plant, but aphids also introduce pathogens like viruses.  

Aphids use a simple but effective defense to escape predators. When an aphid is attacked or under duress it ejects an alarm pheromone from exhaust-pipe looking features protruding from the back called cornicles. This is a signal to other aphids to drop off of their leaf or stem. A once-successful predator that gets marked by the alarm pheromone will have less success catching more aphids.

While the apparent natural defense of an aphid is to simply let go of whatever it is they are attached to, they have another fierce arthropod ally. Certain species of ants will actively farm aphids for their sweet digestive waste called honeydew. These farming ants will manage herds, and even carry aphid eggs underground to nest with their own during the winter. Most importantly, ants defend aphids from other predators like lady beetles and their larvae.  

The first thing to do if a plant is infested with aphids is to wash them off thoroughly with water. Most of the displaced aphids will not find their way back to the plant. Water also washes away the sticky, sugary honeydew that feeds mold. To prevent aphids from recolonizing a plant, spray the plant with an adequately-diluted mix of soapy water and any variety of herbal oils that have been shown to deter insects.

Control ants in the area that may be actively re-establishing the aphids on plants. Check the area around your garden for weeds that harbor aphid colonies like mustards and sowthistle. Aphids can also thrive on the newer growth in the inner branches of trees. Natural predators of aphids like lady beetles (ladybird beetles, lady bugs) can be purchased at a local gardening store or online.