GENEALOGY
Original source for
U.S. release was northern Greece. First U.S. releases were made in
1990. Now established in California, Idaho, Oregon, and
Washington. First known release in Stevens County was made in 1996
on Gold Hill above Kettle Falls.
LIFE CYCLE
Adults which have
overwintered outside the host plant began egg laying activity for
the new year late in spring and early summer. These overwintered
adults feed on and destroy many of the smaller developing flower
heads. Females chew holes in the larger unopened flower heads and
lay their eggs singly. They then cover the hole with chewed
material. In about 3 days the eggs hatch and the larvae begin
feeding on the developing seeds and receptacle tissue. After about
two weeks the larvae fashion a pupal chamber from chewed seed head
content. In another two weeks adults emerge and probably feed on
late developing, small flower heads before overwintering begins.
EFFECT
Both the adult and
larval stage are destructive. Feeding activity of the adults
destroy a high percentage of the smaller unopened flower heads.
Larvae feeding inside the larger flower heads often destroy 100%
of the developing seeds.
REDISTRIBUTION
In Stevens County July
is a good time to collect these agents. Easiest collection method
is to shake the agents off into a collection pan. If possible
release 250-500 at a new site.
COMMENTS
This agent has
excellent potential. It has proven effective at sites in
Washington and Idaho. In Stevens County the agent is well
established on Gold Hill above Kettle Falls and is present at
other sites as well. Starting in 2006 this agent will be the focus
of July collections and redistribution.
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