What's eating my zucchini / courgette?

Zucchini faces several serious pests. Squash vine borers (US) tunnel stems and can kill plants overnight. Cucumber beetles spread bacterial wilt. Aphids and squash bugs cluster under leaves. Slugs shred seedlings. Powdery mildew aside, the combination of squash bugs and vine borers is what most US growers fear most each season.

Sudden wilting of the whole vine; sawdust-like frass at stem base where larvae tunnel inside Wrap stem bases in foil at planting; inject Bt into stems at first sign of entry hole; plant a second succession crop to escape peak moth flight

Yellow then brown patches on leaves; plants wilt; bronze egg clusters on leaf undersides Scrape off egg masses daily; hand-pick adults at dawn when sluggish; use floating row cover until flowering; apply neem oil or pyrethrin as last resort

Chewed leaves and flowers; bacterial wilt disease transmitted causing rapid plant collapse Use row cover until flowering; use yellow sticky traps; apply kaolin clay to deter beetles; remove and destroy wilt-infected plants immediately

Colonies under leaves; leaf curl; honeydew promoting sooty mould; can transmit mosaic viruses Spray with insecticidal soap or strong water jet; encourage aphid predators; reflective silver mulch deters winged aphids from landing