Whitefly

What you see

Tiny 1-2 mm white moth-like insects that erupt in a cloud when you brush the plant. The immobile scale-like nymphs sit flat and translucent on the leaf underside - those, not the adults, do most of the damage.

Damage

Clouds of white when disturbed. Sticky honeydew and black sooty mould on lower leaves. Yellow stippling, general loss of vigour. On tomato, silvering and irregular ripening.

Lifecycle on this coast

Egg to adult in about 3 weeks at summer temperatures, overlapping generations all season. Thrives in still, sheltered, warm air - which is why greenhouses and polytunnels suffer far worse than open beds.

When to act

A handful of adults is normal and harmless. Act when yellow sticky cards show a sharply rising count, or when honeydew starts making leaves shiny.

Months: May, June, July, August, September, October

Plants it bothers

Tomato, Cucumber, Aubergine, Sweet pepper, Cabbage, Basil, Courgette

Natural enemies

Encarsia parasitic wasp, Lacewing, Minute pirate bug, Spider

Remedies

Yellow sticky traps, Insecticidal soap spray, Neem oil spray, Encourage predators

The thing people get wrong

Spraying the adults is nearly pointless - they simply fly up, wait, and land again. Everything that matters is on the underside of the leaf, where the nymphs are glued down and cannot escape. Aim upward, work the lower and middle leaves, and repeat in 5 days to catch the next hatch.