Pests & diseases › Squash Vine Borer
Squash Vine Borer
Day-flying clearwing moth whose larvae bore into squash vines and rot them from inside. Devastating to summer squash, zucchini, pumpkins.
Symptoms
- Sudden complete wilt of a previously healthy vine
- Holes near the base of stem with green-yellow frass (sawdust) pushing out
- Cut stem reveals fat cream caterpillar inside
- Whole plant collapses within days
Lifecycle
Adult moth lays single eggs on stem base June–July. Larvae bore in and feed for 4–6 weeks.
What to do
- Surgery: slit the stem lengthwise with a sharp knife, remove the borer, bury the slit stem to encourage rooting
- Inject Bt directly into stem with syringe at first sign
- Bag and bin (don't compost) collapsed vines
If it's bad
- Permethrin at stem base weekly during egg-laying period
Stop it coming back
- Wrap stem base in aluminum foil or pantyhose (prevents egg laying)
- Delay planting until mid-July (after main flight)
- Resistant types: butternut, tromboncino — borers can't penetrate their solid stems
- Pheromone traps for monitoring
Crops it goes for
Acorn Squash (Pumpkin)
Butternut Squash (Pumpkin)
Giant Pumpkin (Squash)
Hubbard Squash (Pumpkin)
Jack-O'-Lantern Pumpkin (Squash)
Ornamental Pumpkin (Squash)
Pie Pumpkin (Squash)
Summer Squash (Pumpkin)
Watermelon
Zucchini (Courgette)
Plan the plot, track every sowing, cook the harvest
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.