bug is one of the most common and troublesome pests attacking squash
and pumpkin plants. Both nymphs and adults suck sap from the leaves
and stems, apparently also injecting a toxic substance into the
plant, causing a wilting known as Anasa wilt of cucurbits. This
closely resembles bacterial wilt,
a true disease. After wilting, vines and leaves turn black and crisp
and become brittle. Small plants are killed entirely, while larger
plants may have several runners affected. Squash bugs are often
found in large populations, congregated in dense clusters on vines
and unripe fruits. Sometimes no fruits are formed as a result.
bugs are rather large, about 12 mm (1/2 inch) long and approximately
1/3 as wide. Adults are winged, brownish black, sometimes mottled
with gray or light brown and flat-backed; they give off a disagreeable
odor when crushed. The nymphs are whitish to greenish-gray with
black legs. Squash bugs vary in size from tiny, spider-like individuals
when first hatched to the maturing nymphs which are nearly as large
as adults. Young nymphs have red legs and antennae with a green
abdomen. After aging a few hours, the red parts become black. Late
instar nymphs are a dark, greenish-gray color. Eggs are yellowish-brown
to brick red and are laid in groups or clusters.
adult (R.A. Casagrande)
squash bugs overwinter in the shelter of dead leaves, vines, boards
or buildings and fly to cucurbits when vines start to grow. Following
feeding and mating, egg laying soon begins. Masses of eggs, each
containing about a dozen or more, are usually deposited on the undersides
of leaves in angles formed by the veins. Egg laying by the overwintering
females continues until midsummer. Eggs hatch in about 10 days or
more, and the nymphs pass through 5 instars requiring 4-6 weeks
to reach adulthood. Only one generation develops each year and new
adults do not mate until the following spring. Squash bugs are secretive
in habit. Both adults and nymphs are found clustered near the plant
crown, beneath damaged leaves, under clods or in any protective
groundcover. They all scamper quickly for cover when disturbed.
Because of the protracted egglaying period, all life stages occur
throughout the summer months.
of adult squash bugs is very important, as they are difficult to
kill and can cause considerable damage.
If only a few vines are involved, it is best to collect and destroy
the bugs and crush their egg masses. Some people place pieces of
board or shingles on the ground near the plants to concentrate the
number of individuals in an accessible area. Plant remnants may
be composted or burned at the end of the year. It is a good idea
to select varieties of squash and pumpkin resistant to the squash
bug. Since there is only one generation per year, damage can be
greatly reduced by keeping vines covered until blossoming begins.
Remove the cover for pollination purposes.
If mechanical and cultural controls are inadequate, chemical insecticides
registered for garden use can be applied, according to label directions
and safety precautions. Repeat applications may be needed.
from the Ohio State University Extension, 1999. Photo from the Connecticut