Tuesday, 24 September 2013

Lepidoptera: obvious - and less so

Lepidoptera - butterflies and moths - are familiar to us all from early childhood. We soon recognise butterflies, such as the Comma, as they tend to be colourful and diurnal; moths are often duller and nocturnal. In fact many 
Comma, Polygonia c-album, on Buddleia
Byfield, 24 September, 2013
moths are also diurnal but there is another problem: many moths are small - and some are very small indeed. For this reason many are referred to as micro-moths. They are abundant in most habitats but obviously they are easily overlooked. Fortunately their presence may often be revealed by other clues - leaf mines. These are created by the tiny larvae as they munch their way through a leaf between the upper and lower surfaces. Often the mines are obvious, but in some cases they can easily be missed. A case in point is that created by the Poplar Bent-wing, Phyllocnistis unipunctella. It looks rather like a faint snail trail across the leaf, in this instance a Lombardy Poplar beside the playing fields in Byfield. Luckily the bright sunlight helped me to spot it.                       

Mine formed by the larva of the Poplar Bent-wing,
a tiny moth, Byfield, 23 September, 2013

A rather different form of mine is that of the Hornbeam Midget, Phyllonorycter tenerella. The Hornbeam is not a native tree in Northants but is widely planted, and this tiny moth has increased its range as a result of these plantings.

Mine of the Hornbeam Midget, Phyllonorycter tenerella
Byfield playing fields, 23 September, 2013

I am confident that all my readers - both of them - will now go dashing out to seek these fascinating mines. A word of caution is therefore called for: moths are not the only insects to exploit this leafy niche. Numerous two-winged flies also create very similar mines and the final photograph shows the mine of an agromyzid fly, Ophiomyia beckeri. This is a widespread species but I am not aware of any other records of it from Northamptonshire.

Leaf mine on sow-thistle made by the larva of a fly,
Ophiomyia beckeri. Byfield. 10 September, 2013

In my next blog I'll try to be less self-indulgent and write about something interesting!

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