Squash Bugs

Identification and Control of Squash Bugs

Squash Bugs from differing angles


Anasa tristis

Coreidae

USDA Zones:All

15 mm - 17 mm

Feeds on -

Cucumber, Squash,

Pumpkin, Melon

Disease Transmitter

Adults squash bugs are Flat-backed, winged, brown/ black, occasionally mottled with tan / gray or light brown.

Eggs are laid on the undersides of leaves in clusters of a dozen or more .



Egg laying continues until midsummer. The orange-yellow eggs, each about one-sixteenth of an inch in length, appear in neatly ordered rows .

They gradually change to a bronze color before hatching. Only one generation develops each year and new adults do not mate until the following spring.

Nymphs pass through 5 stages (instars) requiring 4-6 weeks before reaching maturity.


Neem Oil




Late instars are of a dark, greenish-gray color. The squash bug is frequently misidentified as a stinkbug. Their appearance is similar and both emit a distinct foul "stink" either when crushed, or congregating in large numbers.

Young squash bugs, are a muddled white to green/gray, with black legs. Newly hatched nymphs have a green abdomen, red legs, and antennae . Shortly after hatching (with in a day), red parts become black.



Squash Bug clusters and eggs

Squash bugs can be found clustered beneath damaged leaves, or in any protective ground cover. They feed by sucking sap from the leaves and stems while 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 have several runners affected.

Early detection of adult squash bugs is very important since they are difficult to kill and can cause considerable damage. It is a good idea to select varieties resistant to the squash bug. Since there is only one generation per year, damage can be reduced by covering vines until blossoming begins. Remove the cover for pollination purposes.


Control

Insecticides are normally not required to manage squash bugs. However, if cucurbits are found wilting early in the season due to squash bug feeding, then an insecticide application may be needed.

Effective Controls are rotenone, pyrethrin, Neem Oil or insecticidal soap.

Neem prevents the larvae from developing normally . It disrupts insects' hormonal balance so they die before they molt to the next life stage. It suppresses some insects' desire to feed and also repels in areas that have been sprayed.


Bacillius thuringiensis [Bt] is somewhat effective against the larvae stage only and should be applied as soon as the larvae are first noticed or suspected.

Inter-plant Garlic, tansy, spearmint or peppermint, amongst susceptible plants. They are believed to be deterrents.

Natural enemies of squash bug are parasitic wasps which parasitize the eggs. Another enemy is parasitic flies which inject eggs into the insect which kill the squash bug once they emerge. Neither of these is considered effective in controlling large infestations.



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