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Clouded Plant Bug
Classification and Description: — The clouded plant bug (Neurocolpus nubilus)belongs to a group of insects collectively known as plant bugs (Hemiptera: Miridae). This group includes the tarnished plant bug and cotton fleahopper. These cotton pests belong to a larger group of insects known as “true bugs,” which include stink bugs and a number of important predatory species (e.g., big-eyed bugs, insidious flower bug and damsel bugs). All true bugs have a piercing-sucking mouthpart (i.e., beak).
Adult clouded plant bugs are about 3/8-inch long with a general brown color mottled by patches of white, yellow, reddish-brown or black. The antennae of both adults and immatures (nymphs) are characterized by having the first segment thicker than the remaining segments. The hind legs are also noticeably larger than the other legs (and those of other plant bugs). Eggs are individually embedded into plant tissue and are not easily found. Immature clouded plant bugs are typically yellowish-green to green in color. The antennae of nymphs are horizontally striped with red and white, giving them a "candy-cane" appearance. A dark-colored spot on the dorsal surface of the abdomen is readily visible in larger nymphs.
Hosts, Life History and Distribution: — Clouded plant bugs are relatively common in much of the United States. Besides cotton, its host range includes evening primrose, goldenrod, honeysuckle, Johnsongrass, morningglory, smart weed, stink weed, soybean, alfalfa, button bush, black willow, and others. Winter is passed in the egg stage. Eggs hatch in the spring, with 3-4 generations occurring each year.
Pest Status and Injury: — Historically, the clouded plant bug has been an occasional pest of cotton grown in Tennessee, particularly in mid to late season. Both adults and immatures cause similar injury. In recent years, clouded plant bugs have been a relatively common occurrence in the southern and central counties of West Tennessee. A reduction in insecticides previously used to control boll weevil, bollworm and tobacco budworm is undoubtedly contributing to the increased status of this pest.
Early-season (pre-bloom) populations of clouded plant bugs in cotton are normally small and composed mostly of adults. Feeding injury appears to be similar to that of tarnished plant bug, causing square abscission. Once blooming begins, overlapping generations of nymphs and adults may be present. Feeding injury to larger squares, in blooms and on small bolls is reminiscent to that caused by the tarnished plant bug. However, data indicates this pest causes more damage than the tarnished plant bug on a per bug basis. During late-season, immatures and adults congregate on squares and within blooms, but significant boll feeding (cat-facing) may also occur. Unlike stink bugs, clouded plant bugs do not appear to specifically target developing seed within bolls. However, injured bolls sometimes abscise or the lint is stained.
Management Considerations and Thresholds: — Damaging infestations of clouded plant bug are most likely during mid to late season. Sweep-net sampling and monitoring square retention is recommended prior to bloom to determine the level of plant bug infestation, including clouded plant bugs. Later in the season, drop cloth or visual sampling is suggested because these techniques are better at detecting nymphs. Specific thresholds have not been developed for this pest. When using a drop cloth, the current recommendation is to use treatment thresholds for the tarnished plant bug but count each clouded plant bug as equivalent to 1.5 tarnished plant bugs. Alternative treatment thresholds of 10 clouded plant bugs per 100 plants or 20% internally-damaged, thumb-sized bolls may also be used. When high numbers of nymphs are present, a single insecticide application may not be sufficient, only giving 60-70% control of clouded plant bug populations. Currently recommended insecticides are the same as though recommended for the tarnished plant bug in the Insect Control Recommendations for Field Crops (PB1768).
Print-Ready PDF Publication (Clouded Plant Bug W110)