158 [July, 



the shrill cry of a bat is not uncommonly heard as it flies from lamp to lamp 

 taking its toll of the insects which swarm around them. CarahxLs violaceus, L., 

 and C. nemoralis, Mull., the commonest species of the genus in this district, are 

 frequently seen at the foot of the lamps foraging within the bright circle of light. 

 But the sjjecies which seems to have made the best use of the lamps, or, at any 

 rate, is most regularly fomid at them and in large numbers is Pterostichiis 

 madidus, F. The rarest species hitherto met with in this group is Cychrus 

 rostratus, L. It is an uncommon insect in the Barnsley district, indeed, I do not 

 think I have seen a dozen examples all told within a three miles radius of the 

 centre of the town. Two of these had most certainly been attracted within 

 the circle of light at the base of the lamps, one of them being so far from a 

 natural habitat as to represent quite a long walk, or some external aid in order 

 to reach the thickly jjopidated part in which it was found. 



Dealing now with the first and more important group, the beetles, whose 

 presence occasion most surprise, belong to the Hydradephaga, and their freqiient 

 occvirrence at light has led me to the following conclusion with regard to their 

 presence in another, and seemingly very different situation. Water beetles have 

 frequently been observed on the glass roofs of greenhouses and other buildings, 

 and the only explanation, so far as I am aware, which has been oiierred for their 

 presence, is the plausible one that the beetles having mistaken the glass roof for 

 a sheet of water, have fallen on it, been stunned and rendered incapable of 

 further movement. The explanation I would substitute for this is not open to 

 the objection which may be raised against the older one, viz,, the absence of 

 injury which one would expect to find after a fall from a height sufficient to 

 stun the insect, and the absence of the signs usually associated with insensibilty. 

 Insects taken at electric light, or on a glass roof, after a moonlight night are 

 usually perfect and active, but exhibit no desire to get away from the immediate 

 neighboiirhood where they are found. 



jEschna cyanea, Mull., with the splendid powers of vision possessed by dragon- 

 flies, once settled on an electric light standard may be approached and picked 

 off without making the least attempt to escape. Although it has not in any way 

 struck either the light or the standard its behaviour in no way differs from that 

 of water beetles foimd at the base of the standard, or on a glass roof. It is 

 therefore, I conclude, more probable tliat all these cases are due to the attrac- 

 tiveness of the light, in the one case of the electric lamp, and in the other of the 

 moon reflected by the glass roof. It is unwise to reason from the specific to the 

 general, but I would suggest that the unconscioiisness of danger which these 

 insects evince is due, not to any shock which they may have received, but to 

 their powers of sight having been rendered ineffective by reason of their 

 concentrating it vipon the light, just as our own sight may be reduced in value 

 by looking at any strong light. It should be noted that those lamps which give 

 a light similar to moonliglit are the ones preferred by insects, or which are most 

 attractive to them. It is a veiy rare occiirrence to see an insect of any kind at 

 or near a lamp which gives rose-tinted or yellow light. This, I think, is a further 

 confirmation of my theory. 



Occasionally a species appears to swarm. One night not a specimen may be 

 seen and the next the standards, and the circles of light at their bases, will be 



