grape rootworm

not listed

NNR - Unranked

not listed

Grape rootworm is a small beetle, a medium-sized oval leaf beetle. It occurs in North America and Mexico. In the United States it occurs from Connecticut west to North Dakota and south to Texas. Based on the number of reported observations, it is uncommon throughout its range, including in Minnesota. Larvae feed on the roots of of wild grape, silverleaf grape, woodbine, and Virginia creeper. Adults feed on the leaves of the same plants.

Adults are oblong, 3⁄16″ to ¼″ (4.9 to 7.0 mm) long, and ⅛″ (2.5 to 3.5 mm) wide. They are entirely dark reddish-brown and are densely covered with grayish or yellowish hairs. The body is oval with straight sides along the middle when viewed from above, and convex when viewed from the side.

The head and mouthparts are directed downward. The forehead (frons) merges with the top of the head (vertex) and is not well differentiated. The antennae are thread-like and long, half to three-quarters as long as the body. They have 11 segments. The second segment is shorter than but more than half as long as the first. It is also shorter than the next four or five segments. The compound eyes are not notched.

The exoskeletal plate covering the thorax (pronotum) is slightly longer than wide. It does mot have flattened lateral margins. It narrower than the base of the hardened wing covers (elytra).

The elytra are ridged and have rows of deep pits (punctures).

The legs are long, slender, and entirely dark reddish-brown. The third segment (femur) of each leg is slightly thickened and does not have a tooth on the underside. The fourth segment (tibia) has a raised, longitudinal ridge (carina) along its length and a pair of small spurs at the tip. The last part of the leg (tarsus) 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. There are two claws at the end of the tarsus. Each claw is cleft at the end (bifid).

Total length: 3⁄16″ to ¼″ (4.9 to 7.0 mm)

Wild grape, silverleaf grape, woodbine, and Virginia creeper

One generation per year: Late May to August

The female deposits an egg under the bark of a host plant. When the egg hatches, the larva (grub) drops to the ground, burrows into the soil, and feed on the roots of the host plant. The grub overwinters in the soil. The adult emerges in late May to early July and feeds on foliage of the host. The adult lives about one month.

Roots of wild grape, silverleaf grape, woodbine, and Virginia creeper

Leaves of wild grape, silverleaf grape, woodbine, and Virginia creeper

Sources

24, 29, 30, 82.

Uncommon

Most sources list this species as Fidia viticida. Until recently, the genus Fidia contained both Old World and New World species. In 2020, New World species were transferred into the new genus Neofidia. The two genera can be distinguished by the presence of a tooth on the under (ventral) side of all femurs in Old World species, which is missing in New World species.

Location: Woodbury, MN