The Bug Man

Spraying pesticides for cockroaches bad for ecosystem

By Richard Fagerlund
The Taos News
Posted 4/11/18

Someone asked me if it was okay to have the perimeter of her house sprayed with pesticides for cockroach control.

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The Bug Man

Spraying pesticides for cockroaches bad for ecosystem


Someone asked me if it was okay to have the perimeter of her house sprayed with pesticides for cockroach control. It is not good for the ecosystem.

Numerous beneficial organisms are in every yard and this is one reason, plus your safety, your family's safety and the safety of pets for not spraying synthetic pesticides. Many insects and other arthropods can be beneficial to your garden in different ways.

Some are pollinators and we certainly need them. Others feed on decaying or dead plant or animal matter, and they are important as well. The most important, if you have a garden, are the predators who feed on plant pests.

Spiders, predatory mites and centipedes feed on numerous pests. It is hard to think of a centipede as beneficial, but the soil centipedes (Geophilomorpha) and stone centipedes (Lithobiomorpha) are very small centipedes that could not hurt a human or pet but feed on numerous insects in a yard and many pest insects.

Some beneficial insects include praying mantids (Mantidae), which prey on a lot of insects and eat black widow spiders. I have had people tell me they find more dead praying mantids in their yard than dead cockroaches after the exterminator has power sprayed the perimeter of their home.

Ladybird beetles (Coccinelidae), also called ladybugs, are a major predator of aphids and other small pests. Ground beetles (Carabidae) are large, black beetles that feed on grubs and insect pupae.

Many soft-winged flower beetles (Melyridae) are predators on pest species. Rove beetles (Staphylinidae) feed on grubs, insect pupae and root maggots, and in some cases, aphids. Other beetles are beneficial.

Recently someone sent me a bunch of beetles he had "infesting" his desert willow. It turned out the beetles were soft-winged flower beetles in the genus Trichochrous, and they were doing good work on the tree helping control real pests. If in doubt about a bug, get it identified, so you don't kill something that is a good bug.

The hoverfly (Syrphidae) feeds on nectar in the adult stage, but in some species, the larval stage is a predator of aphids. Bee flies (Bombyliidae) and tachina flies (Tachinidae) also feed on nectar and pollen in the adult stage while their larvae are parasites of other insects, including pest species.

Some true bugs (Hemiptera) are beneficial, such as assassin bugs (Reduviidae), which hide under leaves and ambush caterpillars. Minute pirate bugs (Anthocoridae) are very small and prey on thrips and other small pests. Some seed bugs (Lygaeidae) are beneficial. The big-eyed bugs (Geocoris spp.) will prey on various plant pests.

Lacewings (Planipennia) are predators of aphids, thrips, spider mites, leafhoppers and other small pests. There are many species of parasitic wasps (Hymenoptera), most very small, that will parasitize and control pest insects. Many beneficial arthropods live in our yards and we should try to protect them from pesticides. The careless use of pesticides will also harm birds and lizards that feed on insects.

If you want to have the perimeter of your home treated, make sure the pesticides are only applied to cracks or openings in the foundation where pests can enter your home. Only apply pesticides where pests are hiding. As mentioned, it is not a good idea to generically spray pesticides all over the ground and the side of your house.

You can contact me and I will offer suggestions on how to control pests without using pesticides that will have a serious detrimental impact on the ecosystem. My email is


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