False chinch bugs are active yet again in South Dakota. Although they are normally only a nuisance pest, their populations can become magnified during cool, wet springs. Last year, false chinch bug populations were high due to the favorable wet spring conditions. Their activity initially started at the western edge of the state and pushed east. With another wet spring in most parts of South Dakota, we expect to see a similar pattern develop in 2020. In high abundances, false chinch bugs can pose a threat to gardens, especially Brassica plants such as broccoli, cauliflower, turnips, and cabbage.
Adult false chinch bugs are a grayish-brown color and about 1/8 of an inch in length (Figure 1). They first emerge from overwintering sites in grasslands and weedy fields. As these areas dry down, false chinch bugs eventually migrate to other landscapes in search of food. The adults lay eggs in the soil near Brassica plants and nymphs hatch in about 4 days. Upon hatching, the nymphs will feed and mature into adults in 3 weeks. There can be several generations of false chinch bugs each year. On years when large populations are present, each generation can appear suddenly in a massive swarm, which is very overwhelming for producers.
False chinch bugs feed by sucking the sap from plants. Injury appears as wilting on the upper leaves, causing them to turn brown with the edges becoming curled. Noticeable damage can occur within days on plants that are heavily infested. False chinch bugs are most active during the evening hours or in the morning. During the heat of the day, they will hide in the soil or underneath plants.
Managing false chinch bugs is generally not necessary unless they appear in high numbers. With regular watering, host plants (Brassica spp.) are often able to tolerate feeding. However, injury to young plants may be more severe and will result in stunting. Applying a pyrethrin or pyrethroid insecticide as a knock-down spray can help reduce false chinch bug populations and lessen their feeding impact. For a more proactive approach, floating row covers may be used as a physical barrier to protect plants from harm. Row covers must be installed at planting to be effective – covering plants after they have been in the ground may trap the chinch bugs and other pests under the cover with the plants.