Green stink bug hatchlings: Young stink bugs (first instar green stink bugs here) gather in aggregations through their first couple instars. (Photo Marlin E. Rice)
Green stink bug, Acrosternum hilare (Say)
The green stink bug is common throughout much of North America (McPherson 1982) and, in southern states, is often confused with Nezara viridula (L.), the southern green stink bug (not found in Iowa). The green stink bug has a wide host range and prefers to feed on woody plants (e.g., dogwood and elderberry). However, as the seeds and berries on these primary food hosts drop off, green stink bugs will seek out other hosts such as soybean. The onset of outbreak populations of green stink bugs in soybean in states such as Kansas, Arkansas, South Carolina, and Georgia has been found to depend on the succession of the their primary host plants and the timing of soybean pod set (McPherson and McPherson 2000).
The green stink bug overwinters primarily beneath leaf debry as an adult and probably has one generation per year in Iowa (McPherson and McPherson 2000, Scheafer and Panizzi 2000). This bug is bivoltine as far north as southern Illinois; however, is likely to have only one generation per year in Iowa (Scheafer and Panizzi 2000). The greatest number of these stink bugs in Iowa migrate up from southern regions later in the soybean growing season.
Unlike beetles and other holometabolous insects, stink bugs are paurometabolous (they have no larval worm-like stage, instead they pass through several nymphal stages or instars). For the green stink bug, it takes about 45.5 days to mature from first instar to adult (Scheafer and Panizzi 2000).
Brown, dusky, and onespotted stink bugs and others, Euchistus spp.
Seasonal cycle of stink bugs in Iowa: The brown stink bug, Euschistus servus (say) probably has two generations in Iowa. This figure may be showing the end of the first generation (mostly completed on other wild hosts) and the second generation which is typically more abundant in soybean. Because of its very wide host range, the brown stink bug is generally not very abundant in soybean.
The Euchistus spp. complex includes several economically important species; e.g., Euchistus conspersus, E. servus (brown stink bug), E. tristigmus (dusky stink bug), and E. variolarius (onespotted stink bug)(McPherson and McPherson 2000). All of these species are common throughout most of North America and feed on a variety of herbaceous and woody plants, preferring the fruits or pods of these plants. All of these species overwinter as adults in leaf litter and crop residue. Most of these species are bivoltine (or univoltine in northern U.S. and Canada) with the exception of E. variolarius which apparently has overlapping univoltine and bivoltine populations.
Brown marmorated stink bugs, Halyomorpha halys
This species is a new pest that will attack a wide variety of plant species, including fruits, vegetables, and field crops. Nymphs and adults attack leaves, stems, fruits, and seeds. Probing and feeding can cause necrotic spots on fruits and leaves and deformation of fruits. It is also considered a nuisance to homeowners because it aggregates on structures in the fall similar to the multicolored Asian lady beetle (Harmonia axyridis.