False Chinch Bugs - June 6, 2001
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
Cooperative Extension has received numerous reports of extremely large numbers of small insects across the Verde Valley. These have been identified as false chinch bugs (Nysius raphanus). False chinch bugs are gray with a slight yellowish tinge and typically no more than 1/8" long. The immature nymphs are smaller and lack wings. Some people get concerned because the nymphs resemble ticks.
False chinch bugs are in the Order Hemiptera also known as "true bugs". They have no larval stage (worm or grub); rather they go through several nymph stages. Nymphs resemble the adults in many ways except they are smaller and lack wings. True bugs have a piercing mouthpart that resembles a straw that folds underneath the body when not using it to feed. False chinch bugs can also release odorous oils similar to stink bugs. This odor is unpleasant but largely harmless to people and animals.
Adult false chinch bugs overwinter and become active in the early growing season. Adults lay eggs where there is abundant food: usually among broadleaf weeds. This year's moist, mild winter produced many cool season annual weeds. False chinch bugs prefer plants in the Mustard family and especially like London Rocket: a yellow flowered mustard that is very common in our area.
One of the most striking things about them is that when they are observed, there are a lot of them - massing sometimes in incredible numbers. The adult stages are highly dispersive (they are commonly found using aerial sampling several hundred feet above ground) and their occurrence at a specific site can be sudden. Apparently, they produce an aggregation pheromone (a chemical compound that insects use for communication) that attracts others to concentrate at a specific site.
Even though they may feed on some landscape plants, false chinch bugs rarely cause significant damage. Most often they will feed on landscape plants where foliage is in direct contact with the ground or turf. They will also feed on some vegetable crops where their damage can cause stunting and/or wilting. They are pests on agricultural crops such as grass or alfalfa hay, cotton, grapes, pistachio, avocado, grain, walnuts, squash, melons, tomatoes, and potatoes.
Early spring weed control is the most effective control method for false chinch bugs. If they enter the home, simply vacuum them up. Spraying is not recommended due to their ability to travel from adjacent areas and reinfest. There have limited natural predators. However, they should begin to decrease in numbers as summer approaches and the temperature rises.
Before closing, I would like to recognize Bill Frank, Assistant Director of Yavapai County Environmental Services, for assisting with identification and control recommendations. Bill is a University of Arizona graduate in entomology and has a wealth of knowledge and experience.
More information about identification and management of false chinch bugs can be found at the University of California Integrated Pest Management Web Site.
The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number.
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Last Updated: March 15, 2001
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