Your first indication of an infestation is likely to be the discovery of white webbing on your Buxus plants, and the discovery of the caterpillars, which are a greenish/yellow colour. If you’re unlucky enough to not find these in time, your next indication will be a severe defoliation of your Buxus!
The moth, which has a wingspan of 4cm, usually has slightly iridescent white wings with a brown border, but wings can sometimes be completely brown.
Young caterpillars are greenish/yellow with a black head, while older ones, which grow up to 4 cm long, also have thick black stripes and thin white stripes all along their bodies.
They produce webbing in amongst the leaves and stems of their feeding area, and feed on the box leaves. They have a voracious appetite!
The caterpillars and eggs can be removed by hand. If you want to use an insecticide, then products containing pyrethrum will be the most effective.
There may be up to 2 or 3 generations of caterpillar a year and they’re most active from April to October. Eggs (which are pale yellow, flat, and measure 1 mm in diameter) are laid on the underside of the leaf, in a flat sheet, overlapping each other. They are hard to see at first, but become easier to find once they mature, as a black spot develops in each egg where the caterpillar’s head is growing. The species overwinters in amongst the webbing on the Buxus leaves. As autumn approaches, the caterpillars will be busy creating their winter habitat, so now is a good time to check your Buxus, before these pests complete their development, ready for wreaking havoc in the spring!
Debbie
