Darren Sheriff is a Certified Professional Nurseryman and Master Gardener. He can be reached at TheCitrusGuy@netzero.com.
 

 
 

Squish the Squash Bug
by Darren Sheriff - posted 05/09/17

Mature squash bugs resemble stink bugs a little bit, but you will know it’s them when you find them on your squash and melons, some of their favorite foods.


The squash bug is common throughout the United States, and it is one of those creatures that truly has a logical name. The Anasa tristis is a true bug, and you surely want to “squash” it when seen.

Although many insects are referred to as bugs, only the insects in the order Hemiptera are true bugs. One of the characteristics of a bug is that insects of this order have piercing-and-sucking mouthparts, which work like a straw to suck plant sap.

Squash bugs are found from Canada to Central America, and are often mistaken for stink bugs. They even emit a foul odor when disturbed and squashed, just like a stink bug; however, true stink bugs are in a different bug family.

Adult squash bugs are rather big, about 5⁄8-inch long and approximately 1⁄4-inch wide. Adults have wings and are brownish black, sometimes mottled with gray or light brown, and have a flat back.

 

 

 

Here you can see the different stages of a squash bug’s life cycle, from eggs (left) to larva to adult.

 


The eggs, which are laid in the spring, are elliptical, 1⁄16-inch long, and yellowish to bronze or brick red. They will darken in color as they mature. They are usually laid in clusters of anywhere from 12 to 20 eggs on the undersides of leaves and in between leaf veins. An average female can lay up to 250 eggs.

When the young first hatch they have a light green-blue abdomen and black heads and legs. As the nymphs grow larger, they first turn light gray and then progressively brownish gray, with black legs and antennae. Usually only one generation per year is expected, except in the southern United States, where there can be two generations in one season.

As you can determine from its name, squash would be this insect’s favorite food. They prefer yellow summer squash, winter squashes such as ‘Hubbard’, and some types of pumpkins. There are a few varieties of squashes that don’t seem to show up on their menus as often. These include Royal acorn and butternut. They also seem to not be a big fan of zucchini squash.


This close up shows you the sucking part of the squash bug, which helps classify it as a true bug.

Squash bugs are very shy, and they will scamper away when approached. They like to hide in plant crowns, beneath damaged leaves or any protected spot. Early detection of adult squash bugs is very important, since once they come to town they are difficult to kill and can cause considerable damage with their feeding.

Squash bugs’ feeding on the leaves will cause spots that are initially yellow, then they turn brown and eventually black and crispy. This is from them sucking all the nutrients out of the plant and leaving it to starve. If the population of squash bugs is so bad that they destroy the plant, especially late in the season, they will turn to the fruit. As they feed on the fruit it will cause scars and sunken areas that make the fruit unmarketable and susceptible to rot.

To control squash bugs, one of the most important things to do is maintain healthy plants. Putting plants in the proper place, watering correctly and not overfertilizing are all important. Healthy plants are usually less attractive to pests and they can actually tolerate some squash bug feeding without you losing your entire crop.

Sanitation is crucial. Adult, unmated squash bugs overwinter in the shelter of dead leaves, vines or pieces of wood and will fly to vines when they start to grow in the spring. You can actually use this bit of their habit against them. Adult squash bugs can be trapped beneath shingles or cardboard placed under the plants. This leaves them susceptible in the morning. You can also disrupt the cycle by plowing over your squash garden, or by rotating your crops.


These brown spots are the first sign that squash bugs have been sucking the nutrients out of your squash leaves.
 

Prevention is your best bet, but if it comes down to using insecticides, there are several out there that are labeled specifically for squash bugs. You will want to scout them out early in the season. Early detection is important because the younger nymphs are easier to control with insecticides. Spray in the early morning hours or the late afternoon – this is the time when the beneficial insects in your garden are less likely to be harmed by the insecticide. Make sure you read the warning labels and follow them explicitly. Beware of the chemical option however, as squash bugs develop resistance to insecticides very quickly.

Within the past decade a disease has been associated with squash bugs — cucurbit yellow vine disease (CYVD). The bacterium is transmitted by the squash bug. It can inflict heavy losses to melons, pumpkins and squash. The affected plants usually exhibit stunting, yellowing and gradual decline beginning about 10 to14 days prior to harvest. The squash bug can also carry the bacterium through the winter and continue to spread it the following spring.

As you can see this “true bug” can really be a nuisance. If you find yourself in the company of it and only have a few vines to worry about, take the title of this article to heart and squish those squash bugs!

 

A version of this article appeared in Carolina Gardener Volume 24 Number 5.
Photography courtesy of Darren Sheriff.

 

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