Spotted wing Drosophila are a growing insect concern
in small fruit plantings
W
est Virginia small fruit growers
need to be on the lookout for
a new invasive insect pest, the spotted
wing Drosophila (SWD). SWD have
become a challenging problem for
fall-bearing berry crops throughout
the state. SWD flies look similar to
native vinegar (fruit) flies whose larvae
typically infest over-ripened fruits.
However, unlike these native vinegar
flies, SWD can infest ripening and
ripe fruit.
Determining SWD infestation
To determine whether SWD
are present in fruit plantings and
if action is needed to control
populations, monitor SWD weekly
before fruit begin to color and
continue monitoring until the end
of harvest. Homemade monitoring
traps can be constructed from clear
plastic deli
containers.
Make several
holes 1/8 inch in
diameter in the
upper half of
the containers.
These small
holes allow
Homemade
monitoring traps
access for
can be constructed
SWD and
from clear plastic
other vinegar
deli containers.
flies, but keep
out other larger insects. Fill containers
with approximately 1 inch of apple
cider vinegar (this acts as the lure) plus
one drop of unscented dish soap. The
dish soap breaks the vinegar’s surface
tension, so the flies sink into the
vinegar and drown rather than escape.
To hang a trap, thread a wire or string
through two opposite holes near the
top of the container and close with
a lid. Hang traps in the fruit zone;
make sure the holes are not blocked.
longer and more pronounced than
other vinegar fly species; however,
the ovipositor may be diffi