Squash vegetable garden invaders

This is one of my favorite times of the year. I picked my first summer vegetable, squash, from the garden this past week.

//

There is nothing better than fresh vegetables right out of the garden as all the hard work begins to pay off.

But there are also problems starting to show up in the garden. Insects were starting to attack the squash and cucumbers -- insects that will attack all members of the cucurbit family, including squash, cucumbers, melons and pumpkins. They eat the leaves and suck the sap from the plant, and some can transmit diseases or damage other types of vegetables.

The insect that gives most squash growers the biggest headache is the squash vine borer that ranges from Canada to Argentina.

Damage is caused by larvae tunneling into the stems of the squash. This tunneling often kills plants, especially when the larvae feed in the basal portions of vines.

Symptoms of squash vine borers are a sudden wilting of a vine and sawdust-like insect waste coming from holes in the stem. The adult moths are known as "clear wings" because the hind wings are almost without scales.

Half-an-inch across the wings and metallic greenish-black in color, the moths are day fliers and are often mistaken for wasps. Larvae are white, heavy-bodied and more than an inch long when fully grown.

The insect overwinters in the soil as a larva or pupa enclosed in a cocoon. The moths emerge in early summer and lay eggs on the stems of the plants, usually in late May.

Upon hatching, larvae bore into vines and complete their development in four or more weeks. They then leave the plant, crawl into the soil, spin a cocoon and transform to a pupa. There are two generations per season in the South.

Various measures can be taken to control this pest: The first is tilling the soil in late winter to expose overwintering insects, and the next is to rotate the squash to another location in the garden each season.

Destroy the vines that have been killed to break the life cycle.

Slitting the infested vine lengthwise and removing borers, or killing them with a long pin or needle can reduce their numbers.

When the vine is split, root development can be encouraged by placing soil over the slit stem after removing the borer.

Plant as early as the weather allows, because borers do not emerge until early summer. Organic growers plant radish around their squash to repel the adults.

Insecticides will control squash vine borers, but they should be used late in the day to prevent harm to bees. Bifenthrin, sevin, esfenvalerate, and permethrin are effective on these insects, but each has a waiting period before the fruit can be harvested. Also, neem oil applied weekly can help control these insects.

The squash bug, one of the more common and troublesome pests in the home vegetable garden frequently kills squash by feeding on its sap.

Leaves of plants attacked by the bugs may wilt rapidly and become brittle.

The adult squash bug is rather large, brownish-black and flat-backed. It is about 5/8 inches long.

The young, called nymphs, are whitish to greenish gray with black legs. They vary in size from tiny and spider-like when first hatched, to maturing nymphs, which are nearly as large as the winged adults.

Squash bugs overwinter in protected places. They appear rather slowly in the spring, mate and begin laying egg clusters about the time vines start to grow and spread. The eggs are yellowish brown to brick red in color and are laid in clusters of a dozen or more on the leaves. They hatch in about 10 days and become adults in four to six weeks. Only one generation of bugs develops each year. New adults do not mate until the following spring.

Adults and nymphs may be found clustered about the crown of the plant, beneath damaged leaves, and under clods or any other protective ground cover. They scamper for cover when disturbed.

Place a small, square piece of old shingle or heavy cardboard under each squash plant. As bugs congregate under it for protection, simply lift the trap and smash them.

Other control methods include early planting and removing eggs and nymphs by hand. Insecticides can be used and the best is bifenthrin or esfenvalerate. Rotenone, an organic control, can be used when the insects are in the nymph stage.

Charles Phillips is a retired Columbia County Extension Service agent and operates of Hort Consulting. Reach him at cphillipshort@com cast.net.