Box Tree Caterpillars have rapidly become a serious pest of Box plants and Box hedges in many parts of the UK. The Box Tree caterpillars can develop in large numbers and in severe cases completely kill box plants. The caterpillars will defoliate plants and leave skeleton like leaves with webbing being created when they reach high numbers, they will even bore into the bark of more mature Box plants. Box tree caterpillars are quite distinctive with black stripes and white dots on a green caterpillar. The first step in protecting your plants is to place out Box Tree Caterpillar moth traps to catch and monitor the male moths, once these are observed , it is likely that the Box tree caterpillars will follow a few weeks later. Nematodes can be used as a biological control against caterpillars. The most effective species of nematode for caterpillar control is ; Steinernema carpocapsae, which is contained in Box Tree Caterpillar Killer.
Nematodes are UV sensitive so are not suitable for application in sunny conditions, Box Tree Caterpillar Killer should only be applied in the evenings to minimise the influence of UV light and to maximise moisture availability for the nematodes. For severe infestations several weekly applications should be applied [ Box Tree Caterpillar packs can be stored in a fridge for up to six weeks but must be used all at once, when the pack is opened ] . Box Tree Caterpillar nematodes can be applied with certain hose end feeders including the Birchmeier AquaNemix, which is available through the Dragonfli website. They can also be applied with hand sprayers, if filters are removed.