Save the Squash: How to Kill Squash Bugs
Zucchinis, cucumbers, melons and pumpkins are some of the easiest vegetables to grow — until the squash bugs take over, that is. Squash bugs attack squash and related plants. They can decimate your squash patch seemingly overnight.
Gardeners seeking to combat squash bug infestations need to learn how to recognize eggs, nymphs and adults. Once identified, you can use the right control to rid your garden of squash bugs.
What Is a Squash Bug?
Originally from Central America, the squash bug (Anasa tristis) is a small 5/8″, brownish-black insect. The body appears armor plated, but it’s actually covered by tiny black hairs that help the squash bug feel its way around the plants. They can fly, and on warm days, they will take a short jaunt to find a mate and food. Squash bugs are sometimes mistaken for stink bugs, but they do not produce the telltale odor that a stink bug does when it’s threatened.
The Squash Bug Lifecycle
Adult squash bugs overwinter in garden debris such as fallen leaves. They can also hide under rocks, branches and shrubs. In the springtime, just when the garden warms up enough to plant squash and pumpkins, the adults emerge, and they’re hungry. They immediately zoom in on garden patches filled with young squash, cucumber, melon or pumpkin plants. As they gather, adults mate and lay eggs on the underside of the leaves.
Adults feed on squash leaves and stems by piercing the outer layer of the leaf and sucking out the sap. The leaves wilt at first, then curl into brownish-gray clumps and die. If the plant can’t produce enough leaves to replace the dead ones, it eventually dies.
Squash bug eggs are easy to spot. The females lay their eggs in a cluster or clump under the lower leaves of the plant. The eggs are oval-shaped and iridescent bronze or dark bronze-brown in color.
Each cluster of squash bug eggs yields approximately 12 or more larvae. As the larvae emerge, they’re ravenously hungry and want nothing more than to feed on your plants. They move about in groups, feeding in clusters until they’re old enough to spread out.
This new generation of squash bugs will eventually reach adulthood, unless you do something about it, or natural predators get to them. If they survive, it will take approximately five to six weeks for them to grow into an adult. As the days of summer draw to a close, this new generation finds safe places to hunker down for the winter.
Gardens in northern areas may experience only one wave of newly hatched squash bugs each summer. Southern gardeners may have to battle two waves of squash bugs, depending on the warmth of the season. An early spring means a great opportunity for squash bugs to produce two generations of young. Constant vigilance is necessary for squash bug control.
Identifying Squash Bug Damage
Squash bugs damage crops in several ways:
- Adults feeding on squash plants suck out the sap, causing the leaves and stems to wilt. Eventually, they destroy plants by killing off all of their leaves, the portion of the plant that makes food through photosynthesis. The plants can’t keep up with the damage and are weakened until they die.
- Larvae and nymphs also feed on leaves and stems, especially lower leaves and stems.
- Adults carry a bacterial disease, Serratia marcescens, also known as cucumber yellow vine disease. Plants infected with this bacteria wilt from both the adult’s feeding action and the bacteria injected into their tissues. Any existing cucumbers or squashes appear stunted and yellowed, and the entire plant may turn yellow before dying. The bacteria can overwinter in the soil, so if you suspect your plants have this disease, grow another type of vegetable in the area for several years until the bacteria is no longer viable in the soil.
Control of Squash Bugs: Barriers
The old saying “the best defense is a good offense” is quite true when it comes to control of squash bugs. Squash bugs are prevalent throughout the United States, and chances are good that there are some in your garden right now.
One of the most effective controls for squash bugs is a simple barrier method called a floating row cover. Row covers are finely woven cloth or plastic fabric barriers that are placed gently over plants. Some are placed over a row of flexible hoops to form a tunnel or miniature greenhouse covering. The row cover allows sunlight and moisture through to the plants, but keeps insects such as squash bugs from landing on the leaves and laying eggs. Row covers are available from online gardening supply catalogs as well as from local nursery and garden centers.
Plant Resistant Varieties
Some plants are more attractive to squash bugs than others. They love any squash, of course, but they also prefer pumpkins and watermelon. They least prefer cucumbers, so if you have a problem one year with squash bugs, try using these controls for squash bugs and plant cucumbers instead of zucchini or other squash varieties. Among squash varieties, butternut and acorn squash are also least appealing to squash bugs.
Use Transplants Rather Than Planting Seeds
Another method to discourage squash bug infestations is to transplant young squash plants into the garden rather than direct-sow seeds. Emerging seedlings are most vulnerable to squash bug attacks, and larger plants are better able to withstand a few assaults. You can start squash plants indoors in cell packs and transplant them outside when they have at least two sets