insect pupates underground, and in trials in Hawaii, spraying dilute neem solution under fruit trees resulted in 100 percent control.14

More important, the neem materials were compatible with the biological-control organisms (braconid wasps) used to control fruit flies. When neem was applied to soil at levels that completely inhibited the pest from emerging from pupation, the parasites developing in these pupae emerged and exhibited normal life spans and reproductive rates. Thus, neem is compatible with biological control of fruit flies. Diazinon ®, the current soil treatment for fruit flies, kills not only fruit flies but their internal parasites as well.15

Gypsy Moth

The U.S. Environmental Protection Agency has approved a neemseed-extract formulation for use on gypsy moth, a pest that is ravaging forests in parts of North America. In laboratory trials, a commercial neem formulation (Margosan-O®) produced 100 percent kill at very low concentrations (0.2 liters per hectare). After 25 days, the larvae were shrivelled, had stopped eating, and were dying. Field tests are in progress.

Horn Flies

Ground-up neem seed and stabilized neem extracts can prevent horn flies from breeding in cattle manure. In recent U.S. Department of Agriculture trials in Kerrville, Texas, cattle were fed a diet containing these neem materials in the feed. The animals readily consumed feed containing 0.1-1 percent ground neem seed. The neem compounds passed through the digestive tract and into the manure where they kept the fly larvae from developing.16


In Australia neem products have been tested against blowflies on sheep. The larvae of these pests penetrate and burrow under the skin of sheep. They are a major economic burden to Australia's farmers because many of the sheep die. In the tests, azadirachtin kept blowflies from "striking" (that is, laying their eggs on sheep).17

As a result of the excitement this discovery engendered, 1,000 hectares of neem have been planted in Queensland at a cost of more than $4 million. At least one Australian company has been established to produce and distribute neem products to sheep farmers.


Information from J.D. Stark. The neem formulation (Margosan-O¬) proved less effective than Diazinon® but at low levels (10 ppm azadirachtin in the soil) provided excellent control for the flies.


Information from J.D. Stark.


Information from J.A. Miller.


Information from M.J. Rice.

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