THE SQUASH BUG
This common blackish or earth-colored bug is usually called the squash
stink-bug. It has a very disagreeable odor which gives it this name.
When disturbed it throws off from scent glands a small quantity of an
oily substance which produces this odor. This is a protection to it for
few birds or animals care to feed on it. Most species of sap or blood
sucking true bugs have a similar protecting odor.
The squash bug feeds largely on squash and pumpkins. It has a slender
beak with needle-like mouth parts which are stuck into the plant for
extracting the sap. It feeds only on plant sap. When it can not get
squash or pumpkins it will feed on watermelons, muskmelons and related
crops. It is very destructive to these crops. It not only extracts sap
thus weakening the plant but it also seems to poison the plant while
feeding. In this way its bite injures the plant something like the
effects of the bed-bug's bite on our flesh. It feeds first on the leaves
and vines often killing them in a few days. Later it may cluster and
feed on the unripe squashes or pumpkins in such numbers as to completely
cover them. Every country boy or girl has seen these stinking bugs on
pumpkins in the corn field, at corn cutting time in the fall.
[Illustration: Pumpkin in field covered with adults and nymphs of squash
stink-bug.]
The squash bug lives thru the winter as the matured winged insect. It
flies from its food plant to winter quarters late in the fall. For
winter protection it may enter buildings, hide under shingles on roofs,
crawl into piles of lumber, under bark of dead trees or stumps or hide
under any similar protection. When its chosen food crops begin to come
up in the spring it leaves its winter home and flies in search of food.
After feeding for a time the female lays patches of oval, flattened,
gold-colored eggs set on edge. When first deposited the eggs have a
pale color but in a short time the golden color appears. In some cases
only three or four eggs may be found in one patch while again there may
be twenty or thirty of them. They are so brightly colored that they can
easily be seen and most boys and girls have seen them on the leaves of
squashes or pumpkins.
[Illustration: Cluster of golden-brown eggs of squash stink-bug showing
two recently hatched nymphs.]
In a few days after they are laid they hatch and out of each crawls a
small, long-legged blackish or greenish young bug called the nymph.
These little fellows usually stay in a crowd hiding on the under side of
a leaf. After feeding for a time their leaf begins to turn yellow and
soon dies. Then they move to a new leaf. As they feed they grow rapidly
and after shedding their skins they change to the second nymph stage.
This shedding of their skins or molting occurs five times before they
mature. Of course each time before the old skin or suit of clothes is
discarded a new one is developed beneath. The females may continue to
deposit eggs for later clusters of young. They become most abundant on
the crop late in the fall. Just before cold weather sets in the adults
again seek winter shelter.
This is a very difficult insect to control. Since it feeds on liquid sap
only it is impossible to kill it by spraying the crop with a poison such
as arsenate of lead. It can not chew and swallow such poison. The young
can be killed fairly well with a spray or dust containing nicotine but
such treatments are not effective against the adults or nearly mature
nymphs. A better method is to destroy all the bugs possible in the fall
before they go to the winter protection and then watch for and destroy
the adults and the eggs masses in the spring when they appear on the
young crop. If the first adults and the eggs and newly hatched nymphs
are destroyed the crop can be protected against the destructive work
later.
OBSERVATIONS AND FIELD STUDIES
Plant a few squash hills in the garden in the spring and also plant a
few seeds in rich dirt in discarded tin cans or flower pots. As the
spring advances and the squashes start to vine watch for squash bugs on
them. Examine in piles of lumber, stove wood and under bark for some of
the bugs before they come to the squash hills. If any are found put them
on the squash plants in flower pots and cover them with a pint mason
fruit jar. Watch for eggs to appear on the plants and also examine for
eggs on the squashes in the garden. When eggs appear examine them
carefully, measure them and write a brief description of them. Try to
mash them between your fingers. When they hatch carefully study the
young nymph and describe it. Can you see the slender beak which incloses
the mouth parts? How many joints are there to the antennae? As the nymph
grows watch it shed its skin. How does it do it? Where does its skin
first crack? Save the cast skin and try to follow the nymph thru all
the nymph stages to the adult. Collect a bottle of the nymphs of varying
sizes from the garden. Examine them and describe the different stages.
Can you see the wings forming on the backs of the older nymphs? How many
small wing pads are there? Examine the adult closely and write a careful
description of it. Can you find where the secretion that causes the odor
is produced? How long will the odor stay on your hands? Can you wash it
off? Spread the wings of the adult and make a careful drawing of one
front and one hind wing showing accurately the wing veins. In the garden
try to protect all the hills of squash from the bugs except one or two
used for your studies. Write a brief description of your methods of
control.
[Illustration: Squash stink-bug adult and nymph extracting sap from
squash.]