Melittia cucurbitae

The squash vine borer (Melittia cucurbitae) is a diurnal species of sesiid moth. The moth is often mistaken for a bee or wasp because of its movements, and the bright orange hind leg scales. The females typically lay their eggs at the base of leaf stalks, and the caterpillars develop and feed inside the stalk, eventually killing the leaf. They soon migrate to the main stem, and with enough feeding damage to the stem, the entire plant may die. For this reason, it is considered a pest that attacks cultivated varieties of squash, zucchini, pumpkin, and acorn squash. The squash vine borer is native to North America, with some reports as far south as Brazil and Argentina. It lives in most temperate North American states, except the Pacific coast. Southern states have two broods a year.

from Wikipedia