Stink bug

Mormidea lugens is a common, easily recognized, relatively small stink bug. It occurs in the United States and southern Canada east of the Great Plains.

Adults are active from May through August. They are found in grasslands and agricultural fields. They feed on grasses, sedges, a variety of herbaceous plants, and a few deciduous trees.

Adults are 3⁄16″ to ¼″ (5.0 to 7.2 mm) in length. The body is shield shaped. The upper side is brown.

The head is small and narrow, much narrower than the thorax. It is tucked into a concave groove in the margin of the pronotum. There is no visible “neck” when viewed from above. There are two large, bulging, compound eyes and two small simple eyes (ocelli). The mouth parts are optimized for piercing and sucking, and take the form of a thick, curved, 3-segmented beak (rostrum). The rostrum is longer than the head and fits into a groove on the underside (sternum) when not in use. The antennae are exposed, conspicuous, slender, and long, much longer than the head but not as long as the body.

The exoskeletal plate covering the thorax (pronotum) is wide, giving the body a broad-shouldered appearance. The angles in the shoulder (humeral) area on each side are rounded and have no projecting tooth. On the front half of the pronotum there are two transverse, ivory-colored lines. The lateral and rear margins have a thin ivory-colored border.

There are two pairs of wings, and they are held flat over the body when at rest. Between and at the wing bases there is a triangular plate (scutellum). The forewings (hemelytra) on the mature adult are as long as the abdomen but do not completely cover the sides of the abdomen. The hemelytra have a thickened section at the base and a thin membranous section at the tip with a clear dividing line between the two. The thickened basal part is comprised of a narrow area (clavus) behind the scutellum when the wings are closed, and the remaining broad marginal area (corium). The scutellum is triangular and large, covering about half of the abdomen, but it is not longer than the corium, and it does not reach the tip of the abdomen. It is narrowed on the rear third then tapered to the tip. The lateral margins have an ivory-colored border. The hindwings are thin, membranous, and concealed under the hemelytra.

The legs are pale. On the hind legs, the fourth segment (tibia) has an indistinct and incomplete groove above. The last part of the leg (tarsus), corresponding to the foot, has 3 segments.

Total length: 3⁄16″ to ¼″ (5.0 to 7.2 mm)

Grasslands and agricultural fields

May through August

Grasses, sedges, herbaceous plants, and deciduous trees

Male stink bugs fight for the right to mate | Mormidea lugens
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Stink Bug (Mormidea lugens)
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