July 29, 2017

1 - Cockroaches in the garden may become pests indoors.

Yard and Garden July 29, 2017

Q.

I found your email searching for what to do about my tomatoes. I see a large number of cockroaches in the evening all over my garden. What do you suggest I use to get rid of them?

- Jon

A.

Cockroaches are usually considered indoor pests and not pests of vegetable gardens. They may inhabit the garden, but rarely eat the plants. I could find no references to cockroaches consuming plants to the extent of being considered garden pests. Some species may inhabit moist areas of the landscape, such as a vegetable garden or an area with organic mulch. The roaches may feed on decaying organic matter and may also be found in compost piles. Problems occur when roaches move from the garden into our homes, businesses, food preparation businesses, offices, and public buildings such as schools.

Since roaches inhabit sewers they may come into contact with human wastes and can bring human diseases into our homes, they can cause food poisonings in some cases, and they are known to induce asthma attacks. Cockroaches may transmit diseases and through their feces and by contaminating our foods and food utensils.

Most pest control recommendations relate to excluding roaches from our structures, eliminating their food and habitat in our structures, and preventing their entry. However, there are some pesticides labeled for cockroach control for use in the landscape and as perimeter treatments of our homes to keep the roaches outside.

Some cockroach pesticides are typical pesticides such as pyrethroids, some are insect growth regulators that prevent the reproduction of roaches, some are desiccants that cause them to dry by damaging their waxy protective layers, and some, such as boric acid are stomach poisons. There are also sticky traps that trap the roaches and prevent their spread and feeding. Choose a product, or an arsenal of products, that will work in your situation. Be sure to read and follow all label directions for maximum safety and effectiveness. Be especially careful to consider warnings related to children and pets.

NMSU Extension Publication Guide to the Biological Control of Some Common Yard and Garden Pest Insects in New Mexico, http://aces.nmsu.edu/pubs/_circulars/CR-607.pdf, provides a lot of information useful to New Mexico gardeners. A couple of good sources of information more specific to cockroaches may be found at the University of California Integrated Pest Management website, http://ipm.ucanr.edu/PMG/PESTNOTES/pn7467.html and the University of Nebraska Cockroach Control Manual, http://lancaster.unl.edu/pest/roachmanual.shtml.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!