Itchy problem of moths on the move

So a country walk in June will usually turn up a few butterflies but rarely any numbers, unless, like last year, we experience a major invasion of an immigrant species from Africa like the red admiral or painted lady.

Recent days have seen a scatter of these visitors, but numbers have been small. Not surprising when you consider the dreadful weather in southern France, Spain and Portugal which has no doubt acted as a barrier to butterflies trying to head northward out of Africa. In some parts of France six months rainfall fell in 24 hours: over a foot of rain.

So far this year butterfly numbers seem to have been fairly low, perhaps a reflection of the colder winter we experienced. Numbers of small whites and large whites have been notably down in my allotment, so at least I might get a few more cabbages this year. However, when it comes to moths, June offers much more variety. I am always amazed at the number of moths that fly around our garden unseen

at night. We wouldn't know anything about them except for the fact that my wife runs a light trap to catch a nightly selection.

The light draws them into a container filled with egg boxes under which they can hide. Each morning the moths are examined and then released, or left to fly off at dusk. These days we don't usually collect specimens, just photos of specimens.

Our garden is of average size in the middle of an estate and planted up with a good selection of shrubs. So far in June we have recorded seven species of butterfly, but 45 species of moth. Among the more spectacular have been the eyed hawk-moth, the elephant hawk-moth and the poplar hawk-moth. These are all large in size with wingspans of 3-5cm (one to two inches). They look huge as they have such thick bodies. All are pretty common and widespread across the county laying their eggs on trees and shrubs like willows and poplars.

Last year I highlighted the problems being created by the brown-tail moth. That's the one which produces caterpillars which can shed their hairs and cause unpleasant allergies in anyone unlucky enough to have them blown onto their skin. Until recently that problem seems to have been largely restricted to Spurn, but now this moth appears to be spreading steadily westward along the North Bank of the Humber, and in May I found many hundreds of webs in a young shelter-belt plantation running parallel to the Humber Bank on Sunk Island, taking the moth's spread almost half-way towards Hull. I say "appears to be spreading west" since it is also possible that they have spread north across the Humber from Lincolnshire.

The large webs created by colonies of brown-tail caterpillars are a fairly distinctive feature and can be spotted from a considerable distance. Some may be more than a foot (30cm) long or wide, and there may be dozens on one shrub.

The large hairy caterpillars have two distinctive red dots on their bodies. The shelter-belt was made of a number of tree and shrub species and it was noticeable that the brown-tail seemed to favour the hawthorn and the ash. Each web produces so many caterpillars that they can pretty well strip a tree or shrub, but in most cases these seem to be able to recover.

Typically, the brown-tail seems to favour coastal habitats, although in the south of England it has spread northward from coasts all the way to London. Recent reports suggest it is also spreading up the middle of the country and has reached Northamptonshire.

It remains to be seen as to whether the brown-tail's next move will be to spread further north in big numbers across Holderness. But the fact, that there are already an increasing number of casual records north of the Humber suggests this could already be happening.

n Howard M Frost is Butterfly Conservation's voluntary organiser of butterfly recording in Yorkshire and can be contacted via their website, www.yorkshire butterflies.org.uk where you can also find daily updates as to what butterflies and moths are being seen across the county.