scentless plant bug

Harmostes reflexus is a common, small, true bug. It occurs throughout the United States, but it is mostly absent from the Upper Great Plains, the Rocky Mountains, and the Great Basin. It also occurs across southern Canada and in northern Mexico. It is found in meadows, fields, open woodlands, and at the edges of lakes and ponds.

Adults are active from spring through fall. They feed on the leaf stalks (petioles) and flowers of a variety of plants, mostly those in the Aster (Asteraceae) family.

Adults are ¼″ to ⅜″ (7 to 9 mm) long and 1⁄16″to ⅛″ (2.2 to 2.7 mm) wide. Like all true bugs in the Rhopalidae family, they lack scent glands. This is the feature that gives the family its common name. The body is elongated oval and fairly hard. The coloration is variable. On most individuals, the base color is pale green, some are reddish-brown, some are yellow (pale). Most have numerous small, scattered, dark, reddish-brown spots, some have none.

The head is small, triangular, narrow, and projected forward. At the front of the head there is a rounded lobe that projects forward between the antennal bases. There are two large compound eyes on the sides of the head and two small simple eyes (ocelli) between them. The mouth parts are optimized for piercing and sucking. They take the form of a long, 4-segmented beak that extends along the underside of the body between the legs. It barely reaches to the hind legs. The two lower jaw-like structures (maxillae) and two lower lips do not have feeler-like structures (palps) attached. The antennae are exposed, conspicuous, and long, at least half as long as the body. They have four segments. The first segment is stout and half as long as the head. It reaches beyond the end of the head by half its length. The second and third (middle) segments are slender. The second segment is shorter than the third. The last segment is spindle shaped and dark. It is stouter and shorter than the middle segments.

The pronotum is narrow in front and widest at the rear. The lateral margins are slightly concave and smooth, not finely toothed. The front angles are projected forward in a sharply angled spine. The rear angles are rounded. The color is variable. It is usually mostly reddish brown, light, dark, or any shade in between, except at the margins. There is a thin pale longitudinal line extending from the front margin to the rear margin. The plate between the wing bases (scutellum) is triangular with an extended, rounded tip. It is always pale, and it has a thin longitudinal line in the middle. The lines on the pronotum and scutellum may be distinct or indistinct.

The abdomen has a flattened border (connexivum), but it is completely concealed on both sexes when viewed from above.

There are two pairs of wings, and they are held flat over the body when at rest. The forewings (hemelytra) on the mature adult are mostly transparent, and they are distinctly longer than the abdomen. They 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 clavus coloration is variable. It is usually reddish brown, light, dark, or any shade in between, except at the margins. The tips of the clavi meet well beyond the scutellum. The surface of the hemelytra is moderately covered with fine pits called punctures (punctate). Each puncture has a single, minute, yellow bristle.

The front and middle legs are slender and pale. They have no spines. The hind legs are stout, and there are 3 or 4 long, strong spines on the underside with shorter, weaker spines between. The last part of each leg (tarsus), corresponding to the foot, has only 3 segments. There is a pair of dark claws at the tip of the last segment.

Total length: ¼″ to ⅜″ (7 to 9 mm)

Meadows, fields, open woodlands, and the edges of lakes and ponds

Spring through fall

Adults overwinter on the ground under cover, including beneath logs and beneath the basal leaves of common mullein.

Petioles and flowers of a variety of plants, mostly those in the Aster (Asteraceae) family

Sources

27, 29, 30, 82, 83.

Common

Neither the genus nor the species has a common name. The common name for the family Rhopalidae is scentless plant bugs, and it is applied here for convenience.

Harmostes reflexulus scentless plant bug

Harmostes reflexus, scentless plant bug, photographed at Barnes Prairie, Racine Co., WI on May 23, 2024. This bug was on oxeye daisy.

SCENTLESS PLANT BUG Harmostes reflexulus
Rob Curtis

Babette Kis
5/23/2024

Location: Barnes Prairie, Racine Co., WI

Harmostes reflexus, scentless plant bug, photographed at Barnes Prairie, Racine Co., WI on May 23, 2024. This bug was on oxeye daisy.