Stink bugs (Pentatomidae) come in a variety of sizes, shapes and colors. Many are pests, feeding on agricultural and home crops; however, some stink bugs are beneficial because they are predators of other pests. These shield-shaped bugs have an incomplete life cycle, which slightly varies among species.

insect stink bug
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Broad "shoulders" and a defined midsection are stink bug characteristics.

Adult Description

Some stink bug species look alike, others are much more colorful, bigger or smaller. All have a few similar characteristics, though, which you help you identify them. Stink bugs are five-sided, and each bug's back is shaped very much like a five-sided shield. Some species have more rounded edges along their bodies than other types. Each adult stink bug has strong wings that fold over the back and overlap each other. A green stink bug adult typically reaches a body length of just over 1/2 to 3/4 inch; a brown stink bug adult typically has a body length of about 3/8 to 5/8 inch.

Like all true bugs, stink bugs have long, tubular mouth parts they use to pierce and suck. Plant-feeding stink bugs pierce plant tissue and suck out the juices; predatory stink bugs use these mouth parts to pierce their prey and drain fluids.

Other defining characteristics of stink bugs vs. other bugs are five-segmented antennae and a highly defined scutellum -- the triangular midsection.

Adults emerge from their protective winter hiding spots during warm months, typically in spring, and begin to lay eggs on host plants. Some species lay several clusters of eggs at multiple times throughout the growing season.

Egg Description

Clusters of stink bug eggs resemble small barrels. Eggs vary in color among the species; some species' eggs even change color as they mature. For example, a harlequin bug's eggs are white with brown stripes, and the green stink bug's eggs start yellowish green or chartreuse and change to grayish-pink, pink or gray.

In general, a female stink bug deposits eggs on the undersides of leaves of host plants. The eggs are small: A green stink bug egg is about 3/64 by 1/16 inch. Each cluster's eggs typically open, or hatch, about the same time, revealing nymphs.

Nymph Description

Like the nymphs of other true bugs and various other arthropods, stink bug nymphs closely resemble their adult counterparts in shape and general description. Most go through several instars, or growth stages between each molting, before becoming adults. The coloration of nymphs changes between instars and also differs from adults' coloration. Another difference between nymphs and adults is that nymphs lack wings.

Generations Per Year

When adults and large nymphs first emerge after winter, most seek weedy areas with tall plants. Pest species prefer to feed on crops after they flower, which occurs later in the growing season.

The number of stink bug generations per year depends on the species, but climatic differences can result in more or fewer generations per year. For example, brown stink bugs may have five or more generations per year in Florida's warm climate, whereas the green stink bug typically has one or two generations per year, depending on the region.

The time it takes for an entire life cycle also varies; green stink bug's life cycle usually spans one to one-and-one-half months.