THRIPS -
these pests are often talked about but seldom seen because
of their very small size and the fact that they spend
a lot of time concealed between leaves and
in flowers. Not all thrips
are bad. There are beneficial thrips which prey on other
pests. Some thrips eat fungi. Even some plant feeding
thrips can be useful at times, consuming spider
mite eggs in their immature stage as illustrated
in the accompanying image. Daylily thrips, Frankliniella
hemerocallis, is one of several types of thrips to
have been reported on daylilies. Thrips are usually yellow,
orange, dark brown or black. Young thrips are most often
whitish or yellow but quite similar otherwise to the
adults, although adults may have wings. Thrips are less
than an eighth of an inch in length, usually much smaller,
and there can be many generations in a year. Damage to
the leaves results in light colored patches or streaking,
often with blackish thrips droppings in the vicinity.
Flower bud damage causes streaks,
distortion and bud drop, and scapes may develop corky
lesions several inches in length. Daylily cultivars vary
in their susceptibility to thrips damage. Problems tend
to increase in dry weather and also where plants have
been heavily fertilized with nitrogen. Keeping plants
adequately watered and encouraging beneficial insects
should limit thrips population levels. Insecticidal soap
can reduce their numbers but may not reach those hidden
deeply between the leaves. |
