262 THE ENTOMOLOGIST. 



in widely-separated localities. That unusual heat may 

 and does increase the broods, and consequently the numbers, 

 of such common species as Pieris Brassicae, P. Rapae, &c., I 

 readily allow. But take some of the other species enumerated 

 by Mr. Rye, such as Pieris Daplidice, Argynnis Lathonia, 

 Deilephila Lineata, and Catocala Fraxini. I think I may 

 assume, without fear of contradiction, that every Lepidopterist 

 will at once admit that the appearance of isolated specimens 

 (one or two of C. Fraxini, and a dozen or so of Daplidice and 

 Lathonia), in widely-separated localities, cannot possibly be 

 attributable to any increase of broods. To what then is it 

 attributable .'' " Oh, the hot season." But why so } If this 

 be the reason, why did my pupaj of Trepida remain un- 

 moved during those two hot summers ? Admitting that the 

 hot season does cause the appearance of rare or almost lost 

 {e.g..) C. Fraxini) species, liow does it cause it .'' Let me put 

 a case. In the early spring of '58 (one of the hot summers) 

 I went to Cubley, in Derbyshire. One of the commonest 

 trees in that locality is wych-elm. In the previous year I had 

 been fortunate enough to discover, in Suffolk, that the larva of 

 a much-prized butterfly, Thecla W-Album, fed in the seeds of 

 that tree. Consequently I hoped to fiijd it in the new 

 locality. Curiously enough, after days of beating, I found 

 one larva. I never saw an imago, and though I regularly 

 beat the trees every spring, for ten successive years, I never 

 met with another larva, or saw the slightest trace of the 

 insect in any shape whatever. Now how did that one larva 

 get there ? Was it one of a brood ? If so, what became of 

 the rest ? If not, where did the parent come from, and what 

 led her to lay one or two eggs on that particular tree ? Why 

 did I never see the insect during eleven years, including ''QQ 

 and '68 } Again, in that same year, I found a considerable 

 number of larvae of a Bombyx I much wanted at the time, 

 Trichiura Cratsegi. I procured a large quantity of eggs from 

 the produce of these, in the autumn. Keeping a few of them, 

 I distributed the remainder. Those I kept duly hatched, and 

 produced moths in '59. I then decided not to keep up the 

 brood, as I could always get the caterpillar when 1 wanted 

 it ; yet, though I diligently searched the hedgerows for 

 miles round, during the nine succeeding years, I never saw 

 another. One more instance. The neighbourhood of Cubley 



