How to Manage Pests
UC Pest Management Guidelines
False Chinch Bug
Scientific name: Nysius raphanus
(Reviewed 12/13, updated 12/13, pesticides updated 9/16)
In this Guideline:
Description of the Pest
The adult false chinch bug is a small bug, about 0.12- to 0.16-inch (3–4 mm) long. It is gray to light brown in color and looks somewhat like a small lygus bug. The false chinch bug nymph is gray with a reddish brown abdomen.
False chinch bugs can occur in high numbers on weeds adjacent to, or within, tomato fields. The eggs are laid randomly on the soil or within soil cracks near weeds. The false chinch bug spends the winter primarily in the immature stage (nymph) on weeds, especially mustards. As weeds dry in spring or are destroyed, false chinch bugs may begin mass migration through tomato fields, where they feed. Nymphs predominate during migration, but adults also may be present. Important weeds that serve as hosts include wild mustard, wild radish, shepherd's-purse, and London rocket. Mustard crops, such as canola, can also be important sources of false chinch bug migration. The most serious infestations result from spring migrations; however, fall migrations can also occur. Insect movement occurs in early morning or evening when temperatures are cool, but bugs can be seen throughout the day. False chinch bug populations are likely to build to high levels during years with high winter rainfall.
False chinch bugs can be an occasionally serious problem on fresh market tomato fruits. Their feeding causes indiscernible lesions on green fruits, which later become apparent as numerous, small black spots when fruits are treated with ethylene to bring on ripeness and color. Feeding on tomato foliage can cause leaves to turn brown and drop. Seedlings or newly transplanted tomatoes can be killed by the high number of migrating bugs more commonly occurring along the field edge.
Outbreaks of false chinch bugs are unpredictable from year to year and for various geographic locations. Monitor adjacent areas and prevent populations from migrating into tomato fields, if possible.
Some control can be achieved by flaming or cultivating adjoining weedy areas, grasslands, or pastures. Frequent cultivation of infested areas may inhibit migrating populations.
Organically Acceptable Methods
Cultural controls are acceptable for use on an organically certified crop.
Monitoring and Treatment Decisions
If large numbers of false chinch bugs are present in fields, treatment may be warranted. Insecticide treatment of tomato field borders may be effective in limiting invasion of migrating false chinch bugs. Treat either in the evening or early morning when chinch bugs are active.
UC IPM Pest Management Guidelines:
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County