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Squash bugs

Squash bugs suck sap from pumpkins and squash, especially young plants and those in flower. Their feeding causes speckled, yellow leaves that wilt and crisp. Adults are hard to kill; the eggs and young are the target.

Pests
Squash bugs and bronze eggs under a pumpkin leaf
Squash bugs and bronze eggs under a pumpkin leaf

What it looks like

Turn over the leaves.

  • Neat clusters of shiny bronze eggs under leaves.
    Bronze eggs Neat clusters of shiny bronze eggs under leaves.
  • Groups of pale grey young.
    Grey nymphs Groups of pale grey young.
  • Brown-grey bugs about 15 mm long.
    Flat adults Brown-grey bugs about 15 mm long.
  • Leaves yellow, wilt and crisp from feeding.
    Wilting leaves Leaves yellow, wilt and crisp from feeding.

How to confirm it

Check undersides and the soil.

  1. Egg clusters

    Between leaf veins underneath.

  2. Board trap

    Lay a board by plants overnight; bugs gather under it.

  3. Feeding speckles

    Yellow specks where bugs have fed.

What to do

Target eggs and young.

  1. Crush eggs

    Scrape egg clusters off every few days.

  2. Trap and remove

    Check boards each morning and destroy the bugs.

  3. Hand-pick nymphs

    Drop them in soapy water or lift with sticky tape.

  4. Clear debris

    Remove old vines after harvest.

Prevent it next time

  • Clear cucurbit debris where adults overwinter.
  • Use row covers early.
  • Grow a trap crop of blue hubbard squash.

What not to do

Do not rely on sprays against adults; they rarely work in gardens.

In the growing guides

Where the guides mention it, with plant-specific advice.

Sources

  1. Squash bug on vegetables, University of Maryland Extension
  2. Squash bugs, UC Statewide IPM Program