What’s the best way to squash these bugs?

What is the best pesticide to use for squash beetle control?

— Ray

What I’ve found to be the most effective approach to controlling squash bugs is to use a variety of control measures and, above all, start on them early. Don’t wait until the plants are overrun with them.

A full-grown squash bug is difficult to control, so starting early is important. The smaller the insect, the easier it is to control.

First, monitor your plants once or twice a week, looking for their eggs on the underside of the leaves. They’re pretty easy to spot; they’re football-shaped and reddish brown to orange in color.

Squashing the eggs keeps the next generation from joining in the fight you already have on your hands.

This alone isn’t enough to control the problem, it just makes the job easier.

Next, you’ll have to apply some insecticides to kill the existing insects. If you’re looking for an organic material, try Diatomaceous Earth or Sabadilla.

Diatomaceous Earth is a naturally occurring mineral that’s made up of fossilized plankton-like organisms called Diatoms that form a sharp, hard shell.

To us, the diatomaceous earth feels smooth, but to an insect it’s like crawling through a barrel of glass shards and barbed wire. It abrades the waxy “skin” on the bug as well as causing lots of tiny cuts and punctures. As a result, the insect desiccates and dies.

Sprinkle it out at the base of the plant and on the underside of the leaves; be sure to wear a dust mask as the dust can irritate some people.

Unfortunately, when it gets wet it loses its effectiveness and will need to be reapplied.

Sabadilla is a botanical insecticide that’s derived from the seeds of a South American lily. It works EXTREMELY well on squash bug if you can find it but has become difficult to find the past several years.

Another nontoxic method of control is to use row covers. They need to be in contact with the ground on all sides of the plant or cover the entire garden.

It’s permeable so air and water will penetrate it and most row covers will transmit about 90 percent of the light so your plants will grow just fine. Though this works fine for a lot of different insect problems, I don’t think in this case that it’s a good solution.

Squash needs bees and flies to pollenize the flowers, and the row cover prevents them from doing that.

You also can cut down the squash bug numbers by placing flat boards or shingles on the ground near your squash plants. The bugs tend to congregate there at night and the boards can be thrown away early the next morning.

One last organic method is to practice what’s called good sanitation. That is, this fall when the garden is done, be sure to remove all the old debris from the garden. The insect overwinters as an adult, hiding in nooks and crannies; dead leaves and debris provide favorite spots for this guy.

There are several synthetic insecticides that do a good job on squash bugs. Again, start early since a small, immature bug is much easier to kill than a full grown adult.

Also, since squash bugs tend to spend most of their time around the base of the stems of the plant and on the undersides of the leaves, applying any insecticide should concentrate on those areas. A synthetic pyrethroid such as Permethrin or Bifenthrin will do a really good job.

You might see some recommendations to use Sevin, but I don’t think it works all that well on them.

Since squash plants depend on bees and flies for pollenization, avoid spraying when these little helpers are present. Only spray when they’re not active, primarily late in the day.

Dennis Hill is the nursery manager at Bookcliff Gardens, http://www.bookcliffgardens.com. Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or email .(JavaScript must be enabled to view this email address).


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