1015.] 231 



ahead, and so extensive that the whole town is invisible from the 

 moorland just above it. That this must be having some effect is 

 shown bv the fact that, as my friend Mr. J. W. H. Harrison told me 

 at the time, he found it necessary, during his researches on hybi'idisa- 

 tiou among the Bistoninae, to obtain hawthorn four or five miles from 

 the town, where the smoke is less frequent and much less dense. Fed 

 on plants from near the town, the larvae sickened of a kind of 

 diarrhoea and died. On the other hand there are several interesting 

 points to consider. 



In the first place, Lepidopterous larvae, especially of the Noctuidae, 

 are by no means uncommon, and often abundant even within the smoke 

 belt, e.g., Noctua haja, F., N. xantJiOijra/pha, F., N. brumiea, 'F.,N. festiva 

 Hb., Triphaena orbona F. (comes Hb.), T. pronuba, Jj., T. fimbria L. 

 It is impossible to say now whether any process of natural selection 

 has taken place which has enabled these species to hold their own, but 

 the fact remains that they feed freely on herbage that kills larvae from 

 other strains. Again, the first British i-ecord for the beetle Bledius 

 defensus Fauv.(i) (guUelmi Sharp (-)), was made on the very edge of the 

 built-up part of the town. Finally, some most interesting examples 

 of insect survivals under unfavourable conditions occur on the banks 

 of the Tees between Grrangetown and Eedcar. Near the railway 

 station at Grrangetown there is a huge slag heap flanked by a narrow 

 strip of filthy grass, coltsfoot, moss, etc., and this is fringed by a foetid 

 sti-eam, stinking most abominably of hydrogen sulphide. A quarter 

 of a mile away is a second slag heap, and between the two is a marsh 

 through which the overflow from chemical works finds its way to the 

 river. The air is redolent of the agreeable odour of rotten eggs, filled 

 with gritty dust from calcining and blast-furnaces, and pierced by the 

 shriek of engine whistles, the roar and rattle of the rolling mills, and 

 the hiss of escaping steam. Nevertheless, in this most unpromising 

 spot can be found, often in goodly numbers, some very local beetles. 

 For example, the two moorland species, Miscodera arctica Pavk. and 

 Pterostichns vitreus Dej., occur here — the latter quite commonly, and 

 the former in small numbers — every year since at least 1910, when I 

 took it first. I suppose that these two species have been carried down 

 in some way from the neighbouring moorland, possibly by a stream, 

 but the interesting feature is that they have managed to maintain a 

 footing here in surroundings so different from their native haunts. 



(1). Ent. Mo. Mag., 1913, pp. 1 aud 14. 

 (2). I.e. 1913, p. 256. 



