eye-spotted tumbling flower beetle

Eye-spotted tumbling flower beetle is a small beetle but a relatively large tumbling flower beetle. It occurs in the United States and southern Canada east of the Great Plains. It is uncommon throughout its range. Adults are found from May to October. They feed on the pollen and nectar of giant ragweed and possibly other flowers in the Aster (Asteraceae) family.

Adults are wedge-shaped and ¼″ to 5⁄16″ (7 to 8.5 mm) in length. They are more or less arched and appear humpbacked when viewed from the side. They are mostly black above with sharply defined areas covered with ash gray, yellowish, or golden yellow (pale) hairs.

The head is large, short, bent downward, black, and covered with pale hairs. It is attached toward the bottom to the body. There are two large compound eyes and no simple eyes (ocelli). The eyes are not hairy, and they do not reach the back of the head (occiput). The antennae are short, reaching just to the middle of the thorax. They have 11 segments. Segments 1 through 4 are dull brick red. Segments 5 through 11 are saw-toothed (serrate) and black. The mouthparts are directed downward. The finger-like sensory mouthparts (palps) are pale. The last segment (palpomere) is triangular on both sexes.

The plate on the upper side of the thorax (pronotum) is black, small, slightly wider than long, and evenly rounded in front. The base is broader than the wing covers (elytra), and it has a broad rounded lobe in the middle. There is a band of pale hairs at the base and on the margins of the pronotum. The plate between the wing bases (scutellum) is triangular, rounded at the tip, and covered with pale hairs, at least on the margins.

The abdomen is narrow and pointed, and it extends well beyond the end of the elytra. The length of the body to the end of the elytra is 3⁄16″ to ¼″ (5 to 6 mm). At the tip of the abdomen there is a long, pointed extension (anal style). The anal style is black and is covered with pale hairs at the base. The underside of the abdomen is striped black and ash gray.

The elytra are usually black, sometimes dark reddish-brown. At the base of each elytron there is a broad, rounded, pale band. The band extends to a point in the rear nearly to the middle of the elytron. Near the middle of the band there is a large, round, black spot. The pair of eye-like spots is the source of the common name and probably also the species epithet of this beetle. Behind the middle of each elytron there is an angulated pale band that on most individuals does not reach the middle margin (suture) or the side margin.

The leg color is variable, mostly reddish-brown or pale yellowish-brown with black areas.

Length to end of elytra: 3⁄16″ to ¼″ (5 to 6 mm)

Total length: ¼″ to 5⁄16″ (7 to 8.5 mm)

May to October

When threatened, the beetle may rapidly take flight, or it may kick its legs back and forth, causing it to tumble unpredictably. This is the feature that gives the family Mordellidae the common name tumbling flower beetles.

Larvae feed within the stems of plants that may be different species than the plants that the adults feed on.

Pollen and nectar of giant ragweed and possibly other Aster (Asteraceae) plants.

Sources

24, 27*, 29, 30, 82, 83.

* "Mordella octomaculata"

This species was originally described as Mordella oculata in 1835. In 1945 it was moved to the genus Glipa. As Glipa is currently defined, this species should not be included. It has been suggested that it be moved back to Mordella or to the newer genus Hoshihananomia. Moving it would require a redescription of the species to be published. To date, that has not happened.

Mike Poeppe
7/6/2025

Location: near Houston, MN

Location: South Minneapolis, Howe neighborhood

See https://www.inaturalist.org/observations/124677687