University of Illinois Extension
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Squash Vine Borer



2 (1 = rare 5 = annual) 


4 (1 = very little damage 5 = plants killed) 


The squash vine borer (Melittia cucurbitae) tunnels in the vines of pumpkins and summer and winter squash; it rarely is found in cucumbers or melons and cannot complete its development except in squash or pumpkins.    


The larva is white, thick-bodied, legless, and 1 inch long when full grown. The adult is a red and black, wasplike moth with clear wings and tends to sit on host plants and beans in the early morning. Reddish brown eggs are laid at the base of the stem just above or below the soil line.

The larva tunnels in the stems of squash, pumpkin, and other vine crops, causing plants to wilt and die in mid- to late season.  

Life Cycle

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Susceptibility varies greatly among varieties. Zucchini, blue hubbard, acorn, and delicata are very susceptible. Butternut squash is highly resistant to attack. When vines begin to run, scout twice weekly for the moths and for the entrance holes and frass. Treat as soon as early damage occurs and again five to seven days later. Then continue scouting and treat as soon as new damage is noted.