Bagworms and 'What's eating my flowers?'
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[JUNE 12, 2006]
After some very severe infestations of bagworms
the past few years, the calls have been coming in all year about the
correct treatment times for bagworms this year. Year in and year
out, the correct treatment time for bagworms is June 15. You can
mark this date on your calendar for next year and be within a few
days of the correct treatment time. With a very cool spring, a week
later may be a possibility. The idea is to have all the eggs hatched
The next problem is what to use. The traditional standby has
been Sevin, but the Bt products such as Dipel and Thuricide have
really taken their share of the market the past several years.
The Bt products have several good points, including safety to
mammals and toxicity to larger bagworms. Since the Bt products
are bacteria that affect only the larvae of moths and
butterflies, it does take a while for the bacteria to build up
to the point where they can kill the bagworm. I won't get into
the discussion about monarch butterflies lighting in the tree
just after treatment (actually these products don't kill the
butterflies -- only the larvae would be killed), as the subject
of Bt and off-target moths and butterflies is still a hot one.
If you are in doubt about whether you have bagworms, check your
trees and shrubs around June 15. You can actually see the small
bags as the larvae build them. They become very noticeable at
about one-sixteenth of an inch long. Treat bagworms early, since
larger ones are more difficult to control, but waiting a week
this year will allow the eggs to hatch into a controllable
Most people think that bagworms affect only evergreens. True,
that is their preferred host group, but bagworms have a huge
number of potential hosts. Through the years I have seen them on
oak trees, grapevines, apples and about any other growing thing
you can think of.
What's eating my flowers?
Many have been complaining of flowers of all species being
eaten off by something. As yet, that something hasn't been
identified. Helping to cure the unknown is difficult, but here
are some possible suggestions and treatments.
Insects can and do take most of the leaves off plants. Most
noticeable is the cutworm family. There are some cutworms that
clip only leaves, while others cut the plant off at the stem.
There are also larvae and beetles that defoliate (see the flea
beetle statement below). Treatments with Sevin or permethrin
insecticide on the flowers and saturating the soil around the
flowers will help.
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"Furry critters" such as rabbits and squirrels also clip off
plants of all kinds. Fences help with rabbits, but squirrels usually
greet the challenge with gusto. Birds, such as robins, are also
notorious for clipping plants. Individual protection with a fence,
can or other means can help. You may also find some effectiveness
from repellents, but they usually work about a quarter of the time.
Diseases can affect the plants as well. With wind or rain, the
dried material tatters out or falls off, looking like something ate
it. A change in weather stops many of the disease problems -- at
least for a while. We can also add herbicide drift to this category.
Vapor from many of the herbicides sprayed on fields and lawns can
and does drift for up to a couple of weeks after the fact with hot
and sunny conditions.
In the end, you'll have to decide if the plants are too damaged
to go forth and grow properly -- if they are even alive. You can try
to replace severely damaged ones with one or more of the treatments
applied to protect them.
Many homeowners are complaining of flea beetles attacking flowers
and other plants. These beetles are small greenish-brown beetles
that resemble small Japanese beetles in shape. They leave pinholes
in leaves or skeletonize the leaves. Treatments with Sevin or other
approved insecticides will quickly dispatch them.
Fulton, unit leader,
University of Illinois Extension,
Logan County Unit]