302 THE ENTOMOLOGIST. 



betulcB are better known to the present genei'ation of collectors, 

 perhaps more specimens than formerly reach the setting-board. But 

 are A. adii^pe and a few others as common as they were? whilst some 

 seasons, such as S. megara seem to disappear altogether, and if we 

 turn our thoughts to the moths perhaps a more marked diminution 

 is observable. We seldom hear of large "takes" of Diacyda oo, 

 or Leucania turca, or CEnectra qtiadra, and still less of the little 

 L. assella, which old Charles Turner — the "beetle man" — once took 

 so commonly. I well recollect, too, the numbers of the pretty little 

 burnet, Zygana meliloti, I once saw floating, like small dark bees, 

 over the bright patches of the golden-flowered bird's-foot trefoil near 

 the railway. I understand none are there now, and if an inference 

 may be drawn from the fact that at that time every possible specimen 

 was netted and boxed by a very tall man (a dealer, I suspect), we 

 need not wonder at the species becoming scarce. From the few 

 foregoing facts it is clear that several species of butterflies (and 

 motlis) have disappeared and others become less common than 

 formerly ; but, on the other hand, is not Plusia moneta a compara- 

 tively new species to the neighbourhood ? for, if I may judge from 

 the number of its yellow cocoons found amongst monkshood, lark- 

 spur, &c., in some of the old gardens in the Forest, the moth has 

 become quite an established " native " ; thus some shght compensation 

 seems to be offered for our losses, and if we try to investigate or find 

 a cause for such changes, we come face to face with an apparently 

 insoluble problem. The greed of collectors, parasitism, and our 

 changing cHmate, cold, and damp have been advanced and discussed ; 

 and in a lesser degree the frequent and extensive fires, and even the 

 increase of our small birds has borne some of the blame (but have 

 they increased ?) ; and as each point seems to arrive at some definite 

 conclusion, do we not often find the experience of the following year 

 "knocks the bottom" out of the argument? Some years ago the 

 large white (P. brassicoB) had become very scarce hereabouts, and my 

 friend, the late J. W. Fowler, said undoubtedly it had gone like 

 cratagi, but the very next season all the cabbage tribe and nasturtiums 

 were skeletonized by the enormous number of the high-smelling 

 larvae of that particular species, and many pupae were to be seen 

 suspended by tail and waist-belt from almost every available position, 

 and consequently a more than usual invasion of brassiccB was pre- 

 dicted for the following season ; but this did not come true, for in 

 due course the various pupae were found to be almost covered with 

 the tiny yellow cocoons of the ichneumon whose work of destruction 

 was complete — so much for parasitism. The extreme heat and 

 unusual drought of 1911 during several months of the summer 

 induced many ordinary single-brooded species to become double- 

 brooded, and even a third family was produced in some cases, 

 because, I suppose, the conditions were favourable for the stages in 

 the early development, and it seems reasonable to argue that this is 

 at least one of the chief factors in the future scarcity or abundance 

 of any species. We are all well aware that in rearing insects a 

 whole brood may be very healthy throughout their changes up to 

 the pupa state, and then the entire family will die most miserably 

 without any apparent cause ; perhaps from a lack of something, in 



