Black-veined white: how to recognise and treat it

Pest

Black-veined white — Photo: Charles J. Sharp, CC BY-SA 4.0, Wikimedia Commons

Symptoms

In winter, nests of a few dry leaves spun together with silk hang in the crown, each holding dozens of small caterpillars.
In spring the caterpillars eat the opening buds and flower buds.
Leaves are eaten down to the veins; young caterpillars feed in groups.
The dry leaf nests stay on the tree all winter, hanging from twigs on a white silk thread.

Organic treatment

In winter, cut off the hanging leaf nests with the caterpillars and burn them.
Pick off the groups of young caterpillars while they still feed together.
Spare the many parasitic insects that can kill most of the caterpillars.

Chemical treatment

A pyrethroid or an insect growth regulator that blocks chitin synthesis, on the caterpillars; follow the label dose 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.

Prevention

Inspect the trees after leaf fall and remove every winter nest.
Control flowering weeds, which feed the butterflies with nectar.
Check buds for caterpillars as soon as they start to open in spring.

Plants it affects

Sources

Figures checked against these sources.