The squash bug is a sap-sucking insect which belongs to the Coreidae family.
Coreidae are called twig-wilters or tip-wilters because they mostly feed on young twigs, injecting juices that macerate the tissues of the growing tips and cause them to wilt abruptly.
Squash bugs are most commonly found on squash plants (hence the name), but they also often appear on pumpkins. Their damage is limited to the cucurbit family.
These bugs are often mistaken for stink bugs, because they are similar in appearance and both have a foul smell when disturbed. However, stink bugs are wider and rounder than squash bugs.
Life Cycle
Squash bugs overwinter in sheltered places like under dead leaves, vines, under boards, and even in buildings. They fly to garden plants to mate as soon as vines start forming.
Female squash bugs lay eggs individually in small clusters of about 20 commonly on the undersides of the leaves, especially between the veins where they form a V. Eggs may also be deposited on stems. Â Eggs hatch in about 10 days and the nymphs require about four to six weeks before maturing into adults.
Both adults and nymphs are secretive and quickly scurry for cover when disturbed. One generation develops each year, although it is possible that in some conditions there is a partial second generation.
The life stages overlap and all of them can be seen at any given time during the growing season. In the fall, especially after the vines have died, the adults, and late instar nymphs often congregate on squash fruits.
The nymphs die when the temperatures drop to freezing while the adults gradually fly or crawl to sheltered places to overwinter.
Identification
Adult squash bugs are somewhat flattened, large insects, measuring 5/8 inch long and 1/3 inch wide. They are usually dark gray to dark brown in colour. The edges of their abdomens protrude beyond their wings and typically have alternating orange-like and brown stripes. They are able to fly, but they often simply walk around on plants. They may also be found beneath damaged leaves and near the plant crown.
The eggs are elliptical, 1/16 in. long, and yellowish to bronze.
The nymphs range in size from 1/10 to ½ inch in length as they progress through five stages called instars. The young nymphs when they first hatch have a light green abdomen and black heads and legs. As they grow larger, they first turn light gray and then progressively brownish gray, with black legs and antennae. They move quickly and often in groups on the undersides of leaves.
Damage
These bugs inject a toxin into the plant and suck the sap right out of it with their sharp, sucking mouthparts. This causes yellow spots that eventually turn brown. The leaves wilt because the damage prevents the flow of nutrients to the leaves, and then they dry up and turn black, crisp, and brittle. The leaves sometimes have ragged holes.
Young plants are much more susceptible to damage and may die from extensive feeding. Larger, more vigorous plants are more tolerant of feeding damage, although they can also be injured or killed if they severely attacked.
Squash bug feeding can decimate young fruits.
The wilting due the bugs’ infestation can resemble bacterial wilt, which is a disease spread by cucumber beetles (another squash pest), so be sure to find the bugs or eggs and identify them correctly.
Unlike cucumber beetles, squash bugs do not vector diseases.
Management Strategy
The most important times to control squash bugs are when the plants are young seedlings and when they are flowering. Late season or fall feeding is not considered very serious.
Early detection of nymphs is important, because adult squash bugs may be difficult to effectively control.
The following methods are used to control/and manage squash bugs.
Chemical method
The following insecticides are recommended for use in controlling squash bugs
- PRESENTO 200SP 5g/20l
- LEXUS 247SC 8ml/20l
- LOYALTY 700WDG 5g/20l
- EMERALD 200SL 10ml/20l
- KINGCODE ELITE 50EC 10ml/20l
- PROFILE 440EC 30ml/20l
Non-chemical control methods
- Pick egg masses off the plants in the morning and later in the day. You can also scrape the eggs off the leaves with a butter knife and let them fall onto the ground, where beetles will eat them.
- Place a board or shingle in the garden at night. During the night, both adults and nymphs will congregate underneath the board. Squeeze between two hard surfaces in the morning and dispose.
- Rotations with non-host crops
- Maintenance of field hygiene, e.g. burn or decompose old squash vines
- Proper weed control
- Planting resistant/tolerant cultivars
- Avoid deep, coolmulches like straw or hay that provide an environment that these bugs seem to love.
Note;
- The best time to apply insecticides is during minimal bee activity, which is typically early in the morning or late at night. Be sure to A good coverage should be ensured underneath the leaves as this is where most squash bugs are found.
- Whenever spraying any insecticide, it is advisable to mix it with INTEGRA 3ml/20l. This is a sticker, spreader and penetrant which improves the efficacy of the product.
- Timely application of the insecticide is very critical for effective control of the moth.
- To avoid resistance build-up by the pest, several insecticides should be alternated throughout the crop season.
