Horse-chestnut Leaf Miner invasion

One of the most noticeable of all new species that have arrived and colonised Britain this century has been Cameraria ohridella, the Horse-chestnut Leaf Miner. It was first recording in Britain in 2002 in London but has spread like wildfire since then, reaching Devon in 2007.

Cameraria ohridella (Dave Green)

Cameraria ohridella (Dave Green)

A new study, published this month in the international journal Public Library of Science One, shows the rapid spread of the micro-moth in the UK using information from members of the public. Interestingly, the study recorded a response by parasitiods to the arrival of C.ohridella. The full report is available to read here.

Not surprisingly, given the very obvious feeding damage caused by the moth, the public and media have been very concerned about the welfare of British Horse Chestnut trees. However, another scientific study published last year looked at the impacts of C.ohridella on the health of infected trees. The news is rather surprising and can be found here.

At this time of year, C.ohridella is in the pupal stage, hidden away among the dead leaves around the Horse Chestnut trees that they inhabit, but come early summer their distinctive leaf mines will be visible on trees across the County.

Horse-chestnut Leaf Miner damage (Richard Fox)

Horse-chestnut Leaf Miner damage (Richard Fox)

Little and Large – moths to look out for this week

Two moths currently around in Devon demonstrate the amazing size range of these fascinating insects.

Horse Chestnut Leaf-miner Cameraria ohridella (Brian Bewsher)

Cameraria ohridella, Horse Chestnut Leaf-miner, caught at light (Brian Bewsher)

One, Cameraria ohridella the Horse-chestnut Leaf Miner, is tiny, measuring only about 4mm from head to tip of its wings. Although sometimes caught in moth traps (including at this time of year), it is the blotchy leaf mines created by the moth’s larvae in the leaves of Horse Chestnut trees that are the most obvious sign of this species recent arrival in Devon.

The Horse-chestnut Leaf Miner was first recorded in Britain in London in 2002, but has spread extremely rapidly both west and northwards. The first Devon sighting was in 2007.

Convolvulus Hawk-moth (Brian Bewsher)

Convolvulus Hawk-moth rescued from a garden pond near Bovey Tracey (Brian Bewsher)

At the other end of the spectrum is the Convolvulus Hawk-moth. This giant has wings over 10 times the length of those of the Horse-chestnut Leaf Miner. Not only does the Convolvulus Hawk-moth have an impressive wingspan of around 11cm, it is also capable of long-distance migration. From its permanent range in Africa, some Convolvulus Hawk-moths fly northwards each year to breed in Europe. The best chance of seeing this moth in Devon is in the autumn and several have been sighted in the past week.