Type of
Agent: Insect (fly, gall midge)
Life Cycle
Egg:
Eggs are laid within twenty
four hours of the mating. They are laid in the flower clusters
in-between the bracts and the clusters in groups of 35. The incubation
period is three to five days. The females usually
lay about 89 eggs. The eggs are white, lengthened ( 0.27 mm or
0.01 in) , and have curved ends. The shell of the eggs are smooth and transparent.
Larva:
The larvae are in the inner part of the
flower clusters and bracts. The galls begin to form inside the
cyathuim
(An inflorescence consisting of a cup like cluster of modified
leaves enclosing a female flower and several male flowers, as in the
poinsettia). It is about five weeks before they leave the gall
for the
soil, where they hibernate until the spring.
Pupa:
The pupas are usually formed in
early April. The pupil stage lasts two to four days. They are
about 2 mm
(0.08 in). They are light brown with reddish brown wings and legs.
Adult:
Adults emerge between mid April
and midday. They mate a short time after they surface. The
females live about three days, but the males only live about 2.4
days.
They have redish-yellow bodies with brown hardened parts.
The
females are 2.3 mm (0.09 in) long and about 0.4 mm (0.02 in)
wide. The
male is 1.7 mm (0.07 in) long and 0.02 mm (0.001 in) wide.
Effects
Distructive stage:
Larva
Plant Species
attacked: Leafy
spurge (Euphorbia esula complex)
Site Of Attack:
The inner part of the bracts
that cover the cyathuim
or develop inside the cyathuim.
They are usually in the distorted or enlarged if there is a gall in
the cyathuim.
Damage to Host:
They attack the seed producing
part of the plant.
Releases
Released in the
United States: not yet released in
U.S.
Now Established In:
Not yet established
Habitat:
Undetermined
Availability:
Not available
How to
Collect: Collect all the galls that
have mature larvae and/or pupa. Put the galls in a plastic bag
and put
them in the refrigerator at 8 degrees C (38 degrees F) to force the
larvae to leave the gall. Then place the larvae in mixture
of sphagnum moss and sand. You can keep it in cool storage to
mimic
winter conditions. The adults should be released in early morning or
late evenings (calm days). They mate on those few days they live.
Links
http://www.hysham.com/rosebudweed/noname.htm
http://dictionary.reference.com/search?q=cyathium
http://www.cdfa.ca.gov/phpps/ipc/weedinfo/euphorbia.htm
By:
S. Richards 2/2005.
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Control Page mtwow.org
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Photo by: http://www.hysham.com/rosebudweed/noname.htm