GENEALOGY
Original sources for U.S.
release was Greece. First U.S. releases made in 1975. Established in
the Pacific Northwest, including Idaho, Oregon, and Washington.
Established in Stevens County.
LIFE
CYCLE
There are as many as five
generations per year. Eggs are injected into leaves and stems. .
Larva hatch and begin to feed on the plant tissue around them. This
causes the plant to form swollen purplish galls which encase the
larva. Most larva pupate inside the gall. Some mature larva leave
the gall, fall to the ground litter, and pupate. Both Larva and pupa
stages overwinter, most inside the gall, some in the ground litter.
The generation that winter catches finish their development into
adults the following spring.
EFFECT
The larva is the
destructive stage.
REDISTRIBUTION
Collect infected plants from July through September. Bind the
galled plants together into "Teepees". Wedge these bundles
into plants that are not infected. Some of the immature midges will
complete their development within the collected galls, emerge, and
attack the new plant. Cooler weather, evening releases, and high
humidity helps the chances for establishment.
COMMENTS
The midge has become prey
of native predators and parasitoids. The usefulness of this agent is
therefore diminishing. It is still an important natural enemy of
Rush Skeletonweed however.
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