California jumping gall wasp

not listed

not listed

not listed

California jumping gall wasp also called simply jumping gall wasp, is a very small cynipid wasp. It is native to western United States including the states of California, Oregon, Washington, and west Texas. It has spread north into British Columbia. It has been reported in several eastern states, where it is believed to have been introduced, including Missouri, Michigan, Indiana, Kentucky, Minnesota, Iowa, and Wisconsin. It was reported in Minnesota in 2000. It is still uncommon in the state, but where it appears it may do so in large numbers. It produces abnormal growths (galls) on the leaves of trees in the white oak group. In Minnesota, this includes white oak, swamp white oak, and bur oak.

The adult wasp is very small, 1⁄32″ (0.75 mm) long. It appears hump-backed. The head is brownish-black. The antennae have 13 segments. The thorax is brown, the abdomen black, the legs reddish-brown, and the wings clear. It is not possible to identify adults in the field due to their small size and similarity to numerous other species. Cynipid wasps are best identified by the galls they produce.

Galls appear on the underside of a leaf in early spring. They mature before the leaves are fully grown. A single leaf may have hundreds or even thousands of galls. Each gall is spherical, white, and 1⁄32″ (1.0 mm) in diameter.

Total length: 1⁄32″ (0.75 mm)

White oak, swamp white oak, and bur oak

Two generations per year: March and mid-April to mid-May

It does not sting.

Asexual female adults emerge in March. They lay eggs on the underside of host plant leaves. Sexual male and female adults emerge from mid-April to mid-May. Second generation galls drop to the ground in June. They jump up to an inch high due to movement of the larvae inside. They continue to jump around “for some time.” The larva pupates in the fall and overwinters in the gall.

White oak, swamp white oak, and bur oak

Adult wasps do not feed.

Sources

30, 82, 83.

Minnesota Forest Health Annual Report - 2000.

Uncommon in Minnesota

This species was formerly named Cynips saltatorius.

Location or County: Bowlus, MN, Morrison County