THE SQUASH VINE BORER

COMMON NAME: Squash Vine Borer

SCIENTIFIC NAME: Melittia satyriniformis

DESCRIPTION: ADULTS - The adults are wasp-like moths, 1 to 1 1/2 inches with orange/red and black bodies and black dots or stripes on the abdomen. The forewings are a coppery-green, the hind wings are transparent and the hind legs have a red/orange fringe.

EGGS- The flat, oval brown eggs are Iaid singly on the plant stems.

*LARVAE - The larvae of this moth is a fat, bumpy-looking white hairless caterpillar about 1 inch in length when mature. It will have a medium to dark brown head and tiny legs near the front.

PUPAE - The pupae can be found in a cocoon about 1inch under the surface of the soil.

LIFE CYCLE: In late spring or early summer, the adult moth lays her eggs one- by-one along the stem of the host plant. The young borers hatch in 1to 2 weeks and immediately burrow into the stem and start feeding on the "pith", the inside layers of the stem. This is the most destructive phase. As the larvae grows to maturity, it eats its way through the middle of the stem causing the stem and leaves to wilt and die. When it is fully mature (4-6 weeks), it will burrow back out of the stem, drop to the soil and pupate. In our long summers there is often enough time for this generation to grow to adulthood, emerge from the cocoon and start the cycle over again. For the generation of larvae that mature in the fall, they will overwinter in the soil in either the caterpillar or pupal state.

HOST PLANTS: Squash plants of all kinds are susceptible including the summer, winter and gourd types. Also at risk are cucumbers and melons.

TIME OF YEAR: From early summer through late fall. As long as the vines will grow, the borers will feed on them. (Approx. June-October in Sierra Vista.)

WHAT TO LOOK FOR: Your first clue of trouble ahead will often be to walk out to your garden and find one or more of your previously-healthy squash vines looking wilted and almost dead. No amount of supplementary watering seems to make a difference. If you look closely at the vine, especially near the base of the stems, you may notice a small pile of greenish or yellowish-white "sawdust" surrounding a hole in the stem. This "sawdust" is the excrement of the borer inside the stem. If you have had problems in the past you might be on the lookout for the rather distinctive-looking adults flying around in the spring. A scan of the stems on your growing plants can show you the single flat, oval brown eggs she has laid. Hand-pick any of these you may find.

PROBLEMS AND DAMAGE: While the larvae is happily chewing away it is destroying the nutrient and water delivery system of your plant That vine will be too Weak to produce fruit and will probably even die. If enough of the vines are destroyed, the entire plant may die.

CULTURAL CONTROLS: Timed plantings, either early or late, may avoid most of the initial egg laying females. There are a couple of varieties of squash that claim resistance to the Vine Borer, Butternut is the most mentioned. Cleaning up and HOT composting or throwing away of any wilted or dead vines will destroy any larvae still growing inside. A good fall clean-up to clear the debris and tilling the soil to 6-8 inches will go a long way toward reducing next year's borer crop. Another tilling in the early spring can expose any remaining larvae or pupae to birds or reptiles looking for lunch. Encourage your plants to branch by pinching back the growth early in the season. Mound soil over the vine at intervals to encourage root growth at leaf nodes. This way, if a borer does get part of the plant, the remainder has a better chance of survival.

TRAP PLANTS: You might try planting just one single squash plant, waiting until it shows signs of severe infestation and then pulling it up and destroying it. This might do away with most of the local population and clear the way for a later planting.

MECHANICAL CONTROLS: For the unsqueamish, you can take a piece of wire and carefully run it up the inside of the stem until you hit resistance and then skewer the little pest that is causing the trouble. Another option is to CAREFULLY slit the affected vine lengthwise until you find the culprit then remove and destroy it. The vine itself may be saved by piling soil or compost around the slit area. Keeping this area moist may encourage the plant to put out roots there if the rest of the plant is in good condition.

As a preventive measure, cover your vining plants with agricultural fleece early in the season to prevent the adult from laying her eggs. Others have reported success in preventing egg laying by wrapping the vines in foil or nylon stocking pieces up to the flowers. Naphthaline mothballs are reported to be a repellent and Diatomaceous Earth sprinkled around the base of the plant will be a barrier to the crawling larvae.

NATURALCONTROLS: Beneficial nematodes in a liquid solution can be injected into the vines to kill the larvae.

BIOLOGICAL INSECTICIDES: There has been some limited success reported in spraying young plants with Bt to try and catch the newly hatched larvae as they bored into the plant. Otherwise you can try injecting Bt directly into the stems above the borer's hole to try and kill the hidden larvae. Rotenone can also be dusted or sprayed on the plants near the bases.

CHEMICAL CONTROLS: Please consult the Agricultural Extension Agent or a Master Gardener Volunteer for current recommendations. Phone 458-1104 in Sierra Vista or 384-3594 in Willcox. Whatever you use, FOLLOW LABEL DIRECTIONS EXACTLY and take the necessary precautions to protect yourself, other humans, non-target animals and the environment.