minute seed weevil

not listed

not listed

not listed

Homorosoma sulcipenne is a minute seed weevil. It occurs in the Unites States and southern Canada east of the Great Plains. Based on the number of available records it is uncommon throughout its range. Adults are active in the spring and summer. They are found on knotweeds (Polygonum spp.).

Adults are black, hard bodied, robust, oval, and 1⁄16″to ⅛″ (2.1 to 3.2 mm) in length. They are convex when viewed from the side. The entire body is densely covered with broad, flat scales.

The head is greatly elongated between the eyes and the mouth parts form a conspicuous snout (rostrum). The rostrum is almost cylinder-shaped, projected forward, and slightly bent downward. It is more than three times as long as wide, much longer than the exoskeletal plate covering the thorax (pronotum), but shorter than the head and thorax combined. The antennae are short, slender, and sharply bent (elbowed). They have 11 segments and are inserted on the rostrum well away from the base. The last 3 segments are expanded and form a club, and there are 7 segments between the base of the antenna and the club.

The thorax is composed of three segments. The first segment (prothorax) is large and prominent and appears to be the entire thorax. It is covered by the pronotum. The pronotum is slightly wider than long, strongly arched at the sides, and almost as wide at the base as the hardened wing covers (elytra). The rear exoskeletal plate (mesepimeron) on the side of the thorax is distinctly raised.

The elytra do not cover the last segment of the body (pygidium). There is a short white stripe at the base of the midline (suture), where the two meet.

The legs are black. There is a tooth on the lower side of third segment (femur) of all legs. The femur on the hind leg is expanded, making the adult a good jumper. The fourth segment (tibia) on the hind leg has a small tooth at the tip. The last part of the leg (tarsus), corresponding to the foot, has 5 segments, but the fourth segment is very small and is concealed within the lobes at the end of the third segment, making it appear to have just 4 segments. At the end of the last tarsal segment there are two claws. On the hind leg there is a small tooth at the tip of the tibia.

Total length: 1⁄16″to ⅛″ (2.1 to 3.2 mm)

Knotweeds (Polygonum spp.)

Spring and summer

Stalks of knotweeds (Polygonum spp.)

Foliage of knotweeds (Polygonum spp.)

Sources

24, 29, 30, 82.

Uncommon

The small number of records for Homorosoma sulcipenne is likely due, at least in part, to it being overlooked because of its small size. and to its similarity in appearance to many other minute weevils.

This species has no common name. The common name of the family Ceutorhynchinae is minute seed weevils, and it is used here for convenience.

Location: Woodbury, Minnesota