Q: Our squash plants are small and we have covered them with cheese cloth. How long should we keep the plants covered to protect them from the squash vine borer?
A: Squash vine borer causes much gnashing of teeth for metro gardeners. Plants look healthy until just before squash as produced then the whole thing rots at the base of the stem.
A moth lays her eggs on the stem when the plant is young and the larvae bore into the squash stem.
A low cost way to prevent borers is to cover plants with cheesecloth or floating row cover (click for sources) until the squash begins blooming. By that time the stem is tough enough to withstand attack and the flowers are ready for bees to perform pollination.