About Stink Bugs
Introduction |
Stink bugs are insects in the order Hemiptera, known to entomologists as the “true bugs.” True bugs are characterized by having sucking mouthparts that they use to suck juices from plants or prey. More speci cally, stink bugs are in the family Pentatomidae, and are distinguished from other hemipterans by having ve antennal segments (penta = ve, tomo = part); other hemipterans have four or less. When disturbed, stink bugs emit defensive liquids from their scent glands that can have a strong odor and a bad taste to discourage predators. Although most are herbivorous on a wide variety of plants, a few are predacious on other insects. Over 50 known stink bug species have been found in Oregon. This guide features some of the common species, and some close relatives, that growers and others might nd on their farms, in their gardens, or in their homes. For species with common names, they are provided under the scienti c name, but not all species possess a common name. In Oregon, a few species of stink bug can be nuisance or agricultural pests, but most are not considered pests and none are dangerous to people. This guide is intended to aid you with identifying stink bugs that you nd around the state to help with pest management decisions or to satisfy your curiosity.
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Anatomy
Feeding
Stink bugs feed by inserting their long mouthparts, called a rostrum or beak, into their food. If feeding on plant sap or soft-bodied insects, they can simply suck out the liquid. If they are feeding on something solid, such as nut kernels or seeds, they inject enzymes that break down the protein into liquid so that they can inject it easily. Both of these types of feeding are likely to cause damage to the plants, and can be a concern to growers and gardeners, as the damage can affect appearance, taste, and plant health. It should be noted that most stink bugs in Oregon are not pests to be concerned about, because their populations do not get large enough to cause large amounts of damage to crops.
These are some common plants are attractive to many species of stink bugs throughout the spring and summer:
These are some common plants are attractive to many species of stink bugs throughout the spring and summer:
- Antelope bitterbrush (Purshia tridentata)
- English holly (Ilex aquifolium)
- Hawthorn (Crataegus sp.)
- Himalayan blackberry (Rubus armeniacus) and other Rubus sp.
- Oregon-grape (Mahonia aquifolium)
- Red alder (Alnus rubra)
- Tree of Heaven (Ailanthus altissima)
- Wild carrot (Daucus carota)
- Wild and weedy grasses
Watch a time-lapse video of Podisus feeding on a caterpillar.
Life Cycle
When the weather warms in the spring and the days get longer, adult stink bugs come out of hibernation to feed, mate, and lay eggs. These adults will die a few weeks later, but their offspring will hatch and develop through the summer. Stink bug egg clusters can have seven to as many as fty eggs, varying by species. After hatching, the young insects, called nymphs, go through ve “instars”, or immature stages, before molting into a winged adult. The rst instars generally remain on the egg cluster but later instars can be very mobile. The different stages can be distinguished by their relative size to one another and the development of the wing pads on the later instars. There is variation between species and some stages can be difficult to discern. Stink bug nymphs will always complete five instars before molting into adult.
At the end of the summer, as days get cooler and shorter, adults will begin to move into hibernation areas and settle down for the winter. Most adult stink bugs spend the winter in leaf litter or under tree bark, but some, like the brown marmorated stink bug, will gather in structures. Some stink bugs are univoltine, or have a single generation per year, but others are multivoltine, completing two or three depending on summer conditions. (Image adapted from illustrations in The Developmental Stages of Some Species of the Japanese Pentatomoidea (Hemiptera), Kobayashi 1967).
Watch a time-lapse video of Brochymena emerging from eggs.