What Does A Squash Vine Borer Look Like?

Squash Vine Borer What's That Bug?
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What Does a Squash Vine Borer Look Like?


Squash vine borers (Melittia cucurbitae) are destructive pests that can cause significant damage to squash, pumpkin, and other cucurbit plants. They are commonly found in North America and are known for their ability to bore into squash vines, leading to wilting, collapse, and ultimately, plant death. Understanding what these pests look like is crucial for effective pest management and prevention.

Physical Appearance

The adult squash vine borer is a moth that resembles a wasp. It has a metallic blue-black body with orange or yellow markings. Measuring about 1 inch in length, this moth has clear wings with a few black veins. The forewings have a distinctive transparent window-like patch near the center.

Life Cycle

The life cycle of squash vine borers starts with the adult moth laying eggs at the base of squash plants. The eggs are small, reddish-brown, and cylindrical in shape. After a week or so, the eggs hatch into larvae, which are cream-colored with brown heads. These larvae tunnel into the stems of squash plants, where they feed and grow.

Feeding Behavior

Once inside the plant stems, squash vine borer larvae continue to feed, causing extensive damage. They tunnel through the vascular tissues, disrupting the flow of water and nutrients. As a result, the affected plants wilt, show stunted growth, and eventually die.

Symptoms of Infestation

Early signs of squash vine borer infestation include wilting of leaves, yellowing, and frass (insect excrement) near the base of the plant. As the larvae continue to feed and grow, the vines may collapse or split open. You may also notice sawdust-like frass or holes on the affected stems.

Preventing Infestation

Preventing squash vine borer infestation is critical for maintaining healthy plants. Here are some preventive measures you can take:

  • Plant resistant varieties
  • Use row covers
  • Inspect plants regularly
  • Remove and destroy affected vines
  • Apply insecticides as a last resort

Controlling Infestation

If you notice squash vine borer infestation, there are a few control methods you can try:

  • Surgically remove larvae from the stems
  • Inject beneficial nematodes into the soil
  • Apply insecticides labeled for squash vine borers


Knowing what a squash vine borer looks like and understanding its life cycle and feeding behavior is crucial for effective pest management. By implementing preventive measures and promptly addressing infestations, you can protect your squash and cucurbit plants from these destructive pests and ensure a healthy harvest.