Squash bug: how to recognise and treat it

Pest

Symptoms

Adults are flat, grey-brown bugs about 1.6 cm long with orange-striped abdomen edges; young nymphs are pale green, older ones grey with dark wing pads.
Shiny bronze to copper eggs in small groups on leaf undersides, often in the angle between two veins.
Leaves get small specks that turn yellow and then brown; vines wilt suddenly and whole plants can die.
Sunken dead patches or corky spots on the fruit, which may then rot.

Hand-pick adults and nymphs every 2–3 days into soapy water, and crush egg clusters as soon as you find them.
Lay a board or heavy cardboard on the soil; bugs gather under it overnight and can be collected early in the morning.
Diatomaceous earth with pyrethrins applied around the base of the plants, where the bugs shelter (allowed in organic production).

An insecticide with esfenvalerate or permethrin, applied when the first eggs appear and again 1–2 weeks later — adults are hard to kill, young nymphs are not. Cover leaf undersides, do not spray open flowers, and follow the label and pre-harvest interval.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Cover young plants with floating row covers sealed at the edges, and remove them when flowering starts so bees can pollinate.
Keep the base of plants clear of debris — mulch shelters the bugs; after harvest remove all crop debris where adults overwinter.
Rotate cucurbits to another bed and plant early so plants are larger when egg-laying starts; an early yellow straightneck, crookneck or Hubbard squash at the edge can serve as a trap crop.
Encourage the tachinid fly Trichopoda pennipes and egg-parasitic wasps with nearby flowering plants, and avoid broad-spectrum sprays.

Figures checked against these sources.