GENEALOGY
Original source for U.S.
release was northern Greece. First U.S. releases were made in 1985.
Now established in California, Idaho, Oregon, and Washington. During
1990 at least 4,600 adult Bangasternus were released in Stevens
County. How well the agent has established is not known.
LIFE CYCLE
Overwintered females lay
as many as 470 eggs in late spring and early summer. Eggs are laid
singly at the tips of unopened flower heads. Hatched larvae tunnel
into the flower head and begin feeding on immature seeds and
receptacle tissue. Larvae pupate into adults within a case
constructed of chewed seeds. Adults about 6 mm long emerge from
their individual seed head case in late summer and overwinter
outside the plant.
EFFECT
Yellow Starthistle
reproduces by seed alone. It is known that a single Bangasternus
larva can destroy 60% of the seeds in a seed head.
REDISTRIBUTION
Shake adults off plant
into a funnel assembly or pan in late spring and early summer. If
possible, release 500 at new sites.
COMMENTS
This agent (along with
Eustenopus villosus) has greatly reduced the Yellow Starthistle
population at a site near Colfax WA over the past decade. In Stevens
County Eustenopus villosus is more established and visible, and is
more the focus of BioControl for Yellow Starthistle.
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