Squash is one of the main crops of the southern summer vegetable garden. Right after tomatoes, summer squash and zucchini are the harbingers of the beginning of the summer harvest. Everyone’s family has a nostalgic recipe and memory of cooking squash, but they also probably have a tale of woe as they also mourn the loss of their squash to squash bugs (or squash vine borer). These small insects are voracious feeders and will suck the juices right out of the plants. Here’s a little help to make sure you can keep harvesting summer squash and zucchini into the future, while also celebrating the beneficial cousins to the squash bugs, the assassin bugs!

What to Be on the Lookout For

You should be on the lookout for at least two generations of squash bugs (Anasa spp.) in May and August in Eastern North Carolina. Regular scouting is critical! The adults survive over the winter and lay their small, shiny, brown eggs usually on the underside of squash leaves (sometimes in melons and rarely in cucumbers) in organized clusters. Sometimes they are tucked along the veins of the leaves. Be on the lookout for the adults, because if you see them then they are surely laying eggs. Look for wilting leaves or dark fecal spots as telltale signs. If the adults aren’t seen, still look at the leaves in May and August to catch the insects at their egg stage.

The Good Guys

While squash bugs are strictly plant pests, some assassin bugs, like the spined assassin bug (Sinea spinipes) and the wheel bug (Arilus cristatus), are predatory insects. These fascinating creatures are often considered beneficial in the garden as they feed on a variety of other pests, including caterpillars, aphids, and even squash bug nymphs. They get their name from their ambush hunting style and the way they inject a paralyzing saliva into their prey before sucking out their bodily fluids. Assassin bugs are often found perched on leaves or stems, patiently waiting for prey. Their elongated bodies and prominent mouthparts are distinctive. However, some larger assassin bug species can deliver a painful bite if mishandled, so caution is advised.

Home Gardener Treatment Strategies

For squash bug management, early intervention is most effective. Handpicking eggs and nymphs is a simple yet powerful method, especially for smaller gardens. Regularly check and destroy any egg masses you find, particularly during peak egg-laying periods in May and August. For larger nymphs and adults, a forceful spray of water can be effective to knock the insects off the plant. Diatomaceous earth, a naturally occurring powder, can also be sprinkled on the leaves of plants to deter them. Row covers placed over young plants can prevent squash bugs from accessing them in the first place. There are other chemical options if the infestation is extensive or there are more than a handful of plants. For more chemical information, gardeners can call the N.C. Cooperative Extension – Lee County Center at 919-775-5624.

When it comes to assassin bugs, the goal is generally to leave them undisturbed to continue their beneficial work. Avoid broad-spectrum pesticides that can harm these natural predators.

Protecting Pollinators

The indiscriminate use of certain pesticides poses a significant threat to beneficial insects, including vital pollinators like bees. Without bees, there is no squash!

Systemic insecticides, which are absorbed by the plant and make all its tissues toxic, are particularly harmful as pollinators can ingest the poison through nectar and pollen. Neonicotinoids are a class of systemic insecticides that have been linked to pollinator declines.

It is crucial for home gardeners to choose pest control methods that are targeted and have minimal impact on non-target insects. Opting for manual removal, insecticidal soaps, horticultural oils, or biological controls have less harmful impacts on pollinators. By being mindful of the products we use, we can protect the pollinators that are essential for the health of our gardens and the wider ecosystem.

Understanding the life cycles and habits of both pestilent squash bugs and beneficial assassin bugs empowers home gardeners to make informed decisions about plant protection. By prioritizing scouting and employing targeted, pollinator-friendly treatments, we can cultivate thriving vegetable gardens while safeguarding the delicate balance of our natural world.