GENEALOGY
Original source for
U.S. release was northern Germany. First U.S. releases were made
in 1992. Now established in Idaho, Maryland, Minnesota, Montana,
New York, Oregon, Pennsylvania, Utah, Virginia, and Washington.
This agent is well established at sites in Stevens county.
LIFE CYCLE
Overwintered adults
emerge from the soil and soil litter, feed on buds and leaves,
mate, and begin to lay eggs in May and June. A distinctive line of
frass is often placed on top of the egg. When the eggs hatch
larvae feed on leaves and other plant parts before moving down
into the soil or litter to pupate into adults. These new adults
emerge in July and August and continue feeding before hibernating
for the winter. If the female emerges before mid-July she often
lays eggs before going to ground for the winter. Presumably, some
of these eggs hatch, and if the larvae find enough remaining food
to develop, will also descend to the ground to pupate into adults
and overwinter.
EFFECT
Both the adult and
larvae are destructive to Purple Loosestrife. Plants that are
attacked are severely defoliated. They turn brown and are easy to
spot.
REDISTRIBUTION
A good time to collect
these agents is from mid May to mid June. Collect these agents by
shaking the plant inside a sweep net. This agent and it's close
relative Galerucella calmariensis readily establish at new sites
which are not flooded year-round. If possible release 250-500 at a
new site.
COMMENTS
About 70-80% of the
Galerucella releases in the U.S. are Galerucella pusilla. The
remainder are Galerucella calmariensis. They are very similar. The
photo of the eggs and larva are Galerucella calmariensis, but
Galerucella pusilla eggs and larvae look the same. These agents
are a success story almost everywhere they are found. Within a few
years after being released at Purple Loosestrife sites in Stevens
county that weed has been heavily impacted. Occasional releases
are still being made in Stevens County, but the agent seems to be
doing well on it’s own.
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