Squash Vine Borer
The squash vine borers can cause serious damage to squash and gourds. They bore tunnels in the stems of plants and eventually kill the plant. Borers spend the winter in the soil as larvae or enclosed in cocoons. Moths emerge in late spring and early summer and lay eggs on the stems of the plants, where young larvae can bore into the stems and begin feeding inside. Eggs of the squash vine borer are tiny, brown disks on underside of the leaves, and on the blossoms. The best way to prevent borers is to find these eggs and destroy them. Don't just brush them off to land elsewhere on the plant or the ground.
Signs of theses pest are a hole in the stem of the plant with sawdust-like waste coming from it and a sudden wilting of the plant. By slitting infested vines lengthwise early in the borer's attack, and removing borers, then covering the slit stem with soil to encourage it to root and renew the plant, it's possible to get rid of the pest. If you do this make sure you water regularly. Usually, once inside, they are impossible to control. Destroy and remove vines that have been killed.
Prevention:
-If you turn the soil in late winter to expose the over-wintering pests to cold which will kill them, you can stop them from showing up next year.
-Plant as early as the weather allows, since the borers do not usually emerge until late spring or early summer.
-Plant with/close to radish plants as radishes repel squash vine borers.
-Some squash and pumpkin varieties such as Butternut and Green-Striped Cushaw varieties are nearly immune to attack, but others such as Hubbard squash are very susceptible.
-You can help protect plants from borers by spraying the stems and undersides of the leaves with Thuricide as soon as the plants begin to grow and continuing spraying throughout the growing season. Avoid using any pesticides on squash that are harmful to bees, which are so important for pollinating squash.