Answer: I believe you are asking about the squash vine borer -- this pest has one or two life cycles a year and hibernates under the soil as either larva or pupa in a cocoon. The moths emerge early in the season and lay eggs on or near the plant's base. The borers then attack stems in the early summer. Here is a web page http://ctr.uvm.edu/ctr/el/el84.htm with a more in-depth description of the life cycle.
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