Those crawly, creeping, hairy creatures which tickle our body
parts after unsuspectingly leaping from nearby trees—sharpening
the screaming ability of non-nature lovers, invading premises
by scaling walls, staining swimming pools with their body carcasses
and presenting a grotesque display when gathering in teaming masses
on the trunks of trees. These creatures-of-crawl are usually referred
to as "worms", as well as several other not-printablables!
However, the term "worm" is not scientifically correct.
A worm is a legless animal with a slender, soft body. True worms
are made up of many cells. But they do not have a backbone. Most
people think of the worm-like larvae (young) of butterflies and
other insects as "worms". But scientists who study animal
life consider only certain adult animal as true worms.
The creature that most recently has begun invading our privacy
is really a caterpillar. A caterpillar is a worm-like creature
that is the second, or larval, stage in the life history of butterflies
and moths. When a butterfly egg hatches, a tiny caterpillar crawls
out and begins to eat. The caterpillar grows, but its skin does
not grow with it, as does the skin of most animals. Soon the skin
becomes too tight and the caterpillar prepares to throw it off.
A split appears on the upper part, near the head end, and the
caterpillar wriggles out. It appears in a new soft skin formed
under the old one. In a few days this, too, is outgrown, and the
process is repeated a number of times.
Caterpillars are heavy eaters. A butterfly or moth does all
its growing during the caterpillar stage. The larva stores up
the tissues that later are transformed into the adult insect.
The adult grows no more after it grows wings.
The culprit that most folks are "excited" about nowadays
is the forest tent caterpillar. They get their name because their
eastern relatives named appropriately, the eastern tent caterpillar,
spins a loose, white web that looks like a tent. This web envelops
tree twigs and is the home for a group of caterpillars. However,
the "worm" which we love to hate is the forest tent
caterpillar and, even though the term "tent" is included
in the insect's nomenclature, the forest tent caterpillar does
not build a tent (hmm—must be an Aggie deal!). The name
confuses people into believing that this is the webworm that does
definitely build webs in trees in this area. However the webworms,
which spin webs over the foliage on which they feed in the summer,
can sometimes cover whole branches and trees with their webs.
These two worm pests have completely different appearances.
Our little swimming pool buddies, the forest tent caterpillar,
is tent-less, have a row of yellow spots along its back. It is
black and hairy with blue spots on the sides of its cuddly, little
body. The webworm, in contrast, is a much smaller creature (about
one inch when full grown) which is pale yellow or green with a
broad, dusky stripe running down the back, bordered on each side
by a yellow stripe. The webworms are covered with tufts of long
Who cares what they look like or what is their name? Where do
these devils come from and how can they be killed? In midsummer
the female moth of the forest tent-less caterpillar lays brown
egg masses on tree twigs. The eggs hatch the following spring
(in April). After feeding for about six weeks, the larvae enter
the pupa stage in which they spin silky cocoons around themselves.
After three weeks, they emerge as full-grown moths, mate, lay
their eggs, and die. Webworms overwinter as pupae in silken cocoons
under ground trash or on rough tree bark. Moths emerge to disperse
and deposit eggs in hair?covered masses on the underside of leaves.
Anything that kills can be used. A fly swatter, a big foot,
boiling water and automobile tires which will crush their creepy,
little bodies are effective. If you are a mass murderer and want
to use an insecticide, any will work. The legal-to-use insecticides
for forest tent-less caterpillar are carbaryl (Sevin), Malathion
and acephate (Orthene). These are the what-you-spray-you-kill
insecticides, i.e., if the caterpillars are on a brick wall, which
hopefully they are not eating, you have to spray them with a contact-kill
insecticide. If you locate the foliage that they are feeding on,
you can spray with these insecticides or use the super-safe, organically
approved Bacillus thuringiensis (Dipel, Thuricide, Bactur, Biological
Worm Killer) insecticide. Bacillus requires a several day waiting
period before the worm actually dies, even though they cease feeding
activities immediately. So, for those of you who are immediate-gratification
killers, you should carefully use one of the other products mentioned.
FOLLOW LABEL INSTRUCTIONS—remember, you can only kill each
caterpillar ONCE and dead IS dead.
The black "tanglefoot" products are not as effective
on the masses of worms as insecticide sprays. Sticky substances
do not keep the "worms" out of the trees since the female
moth of the forest tent-less caterpillar lays brown egg masses
on tree twigs. If you could remove the wings of the moth, maybe
the sticky stuff would do some good. The caterpillars that you
see on the trunks of trees are not having a revival; they are
shedding their old skin. Remember, the caterpillar grows but its
skin does not grow with it, as does the skin of most animals.
The skin becomes too tight and thecaterpillar prepares to throw
it off—they feel like you do after wearing a too tight girdle
all night; something has got to give! In a few days, after eating
for 24 hours every day, the new skin is outgrown and the process
is repeated. This occurs a number of times.
Now you know the real name of the "worm" with which
you have become so intimate with during the past week or so and
how to "get some satisfaction". These pests will disappear
in a couple of weeks and will only be fond memories until next
spring about this time when THEY SHALL RETURN!
Often, a great number of
caterpillars which hang from strains of webs
that get all over you when you walk under the trees are
Forest Caterpillars" but rather Oak Leaf rollers and
Canker Worms. The
Forest Tent Caterpillar does not descend from the tree on
a web. The
controls for all of these foliage feeding larvae (worms)
are the same.