60 
A. COTTAM—NOTES ON THE HABITS 
partial, as they seem always ready if there is a little warm weather 
to revive and feed a little. 
I have before mentioned the tendency to melanism amongst 
insects bred in the north. There are a good many instances of 
this among the Geometrse, but I will mention only one. 
About fifty years ago—no exact record seems to have been kept 
—a black variety of the common peppered moth (Bistort betularius) 
was taken in the neighbourhood of Manchester, before which time 
it was quite unknown. Since then this variety has become more 
and more common, and has spread all over the country. At the 
present time both forms are equally common. Another curious 
thing about it is that the moth seems at the same time to have 
increased in size. I have taken dark specimens, though not so 
black as the Manchester form, in this neighbourhood. 
Another species of the same genus, Biston hirtarius, has some 
curious habits. Its favourite haunt in this country is London, and 
it may be found in abundance in the squares, parks, and suburban 
roads, particularly those planted with lime and poplar trees. It 
is occasionally taken in the country, and then generally attracted 
by a strong light, but in London light seems to have no attraction 
for it. It is very rare to find one sitting on a street lamp, though 
it may be found on a tree close by. It is on the wing in March 
and April, and has a habit of sitting for days and nights on the 
same tree without moving, its wings laid flat close to the bark. 
There are a good many species in this group in which the females 
have either very rudimentary wings or none at all. These are 
generally species that are out in the late Autumn or early Winter. 
The females are found sitting or running about upon the stems or 
twigs of the food-plant, and they lay their eggs during the Winter, 
the larvae hatching out in the Spring when there are some buds 
or leaves to feed on. 
I must not conclude without some further remarks upon the 
attraction of light. It provides a method that may be used to 
attract moths of all kinds as well as other insects. 
The fascination of light is evidently an unnatural one, for 
insects try to avoid it and will hide in any dark corner after being- 
drawn to it. 
All moths appear to have two periods for flight, one early, as 
soon as it is dusk or even before, and another later in the night. 
Light appears to have very little attractive power early in the 
evening; the best time is during the second flight from 11 to 2 in 
the morning. 
The more powerful the light the better, the best of all being 
the electric arc-light. This will even attract moths comparatively 
early in the evening. 
The next best I believe to be a powerful oil-lamp. This method 
is by far the best for collecting in the Fen districts. I have a lamp 
with four burners giving a splendid light, and when I am in 
Norfolk among the fens and reed-beds there, we fix this on the 
top of the mast in a lighter, and slowly punt (or quant, as they 
