Many people ask me how to
reduce gypsy moth damage on the trees in their yard. This page is a
summary of what I do around our house.
NOTE: It is illegal to use
pesticides on pests for which it is not registered. Also,
registrations change periodically so be sure to check and follow the
“label” of all pesticides before using.
LIFE CYCLE OF THE GYPSY
control the gypsy moth around your house it is essential to know the
Passes the winter as an egg in buff coloured soft mass, usually on
the trunk or large branches of trees. (Egg masses are also found on
the sides of buildings, firewood, etc.) There are usually about 500
eggs in an egg mass.
Larvae: During May
tiny caterpillars emerge from the egg masses. They feed until July.
They prefer oak, walnut, willow, crab apple and Colorado blue spruce,
but will feed on almost any type of tree or shrub.
Pupae: In July the
caterpillars turn into moths by entering a pupae stage. The pupae are
smooth, dark reddish brown in colour and about 12 mm long.
Moth: The male moth
is brownish tan with well developed wings. The male is a strong
daytime flyer. Compared to the male, the female is whiter, much
larger and her wings are not well developed. (She cannot fly) Shortly
after pupating, the moths mate, lay eggs and die.
The control method I use
consists of the following:
Prevent the moths and
caterpillars from climbing the trees so that damage is reduced, and
so that egg are more likely to be laid within reach where they can
easily be destroyed.
Destroy all eggs and as
many larvae and pupae as convenient.
In the spring place a
strip of duct tape around the trunk of the trees you want to
protect. This must be attached to the tree close enough that the
small caterpillars can not crawl under it. If the bark of the tree
is rough, I use a staple gun while I am applying the tape to make a
tight fit in the bark hollows. Some people fill the spaces with
spray foam insulation.
Coat the duct tape with
a layer of “Tanglefoot”, (available at some garden centres).
This stops the caterpillars from climbing the tree. Caterpillars
that are already in the tree will often fall or jump out. This
prevents them climbing back into the tree. Maintain this sticky
barrier until egg laying is finished.
Destroy eggs in the
nests by coating them with dormant oil, (available at most farm and
garden supplies). Do this in the fall when egg laying has finished.
I experimented with WD40 and it was 100% effective. DO NOT GET OIL
ON THE NEEDLES OF COLORADO SPRUCE TREES! You could also remove the
egg masses with a vacuum.
Kill as many of the
caterpillars and pupae by crushing or cutting them while they are
within reach, trapped below the tape.
Keep the caterpillars
out of the tree by preventing the eggs from being laid out of reach
and by keeping caterpillars from climbing into the trees.
Destroy as many of the
egg masses as possible. (The tape will keep the masses within reach)
Kill as many of the
caterpillars and pupae as you can.