Apple ermine moth

​

There has been a proliferation of an orchard specialist moth with larvae that live in webbed tents woven into the young growth of apple trees, appearing in late spring. If you have seen this in the last few years, particularly 2026, it's most likely the work of the apple ermine moth, Yponomeuta malinellus. Populations of this once uncommon species have burgeoned in recent years. The first recorded sighting was in Cambridgeshire in 1965, following which the occasional one or two turned up across the county, from Pembrokeshire to Yorkshire, and once in Northern Ireland.

 

A distribution like this indicates that it has probably been widespread for some time, but on the edge of its range, so never reached the numbers to be a bother. Additionally, populations will have been under-recorded due to its close similarity to other ermine moth species.

 

However, something has changed (what could it be?) and we are now seeing it in epidemic levels. At its worst, entire trees are defoliated. Although there is notable population regulation by a parasitic wasp, Ageniaspis fuscicollis, nature has not yet found that predator-prey sweet-spot.

 

Can you help us monitor and research this newcomer? A simple survey of the larval tents will enable us to monitor its spread, population changes, and determine if there are factors that may affect its choice of host tree.