Insects. 



6281 



connection appears to hold good with P. Agestis. It is somewhat 

 remarkable that long before the above facts as to P. Artaxerxes had 

 even been suspected, the southern P. Agestis and the Helianthemum 

 were associated together. Dr. Jordan, in a communication to the 

 ' Zoologist' for 1844 (Zool. 348), on the occurrence on the Polyommati 

 in South Devon, says "P. Agestis double-brooded, May and August; 

 local ; frequents rocky places in woods. I took it in considerable 

 plenty in Bradley Woods, near Newton, Devon, settling on the flowers 

 of the Helianthemum vulgare, though I did not see a single specimen 

 until I came to the rock where this plant was growing." In reply to 

 my inquiries as to this point, Mr. Cooke writes me, I have never 

 taken P. Agestis, except in localities where the Helianthemum grows 

 freely. The wild geraniums do grow here (Brighton), and in many of 

 the localities where P. Agestis is taken, but they occur only sparingly ; 

 and in one spot, where I take my finest specimens, and where indeed 

 1 caught the curious variety you allude to (mentioned above), I have 

 reason to believe the geraniums do not grow at all." Further, I may 

 add that Mr. Gregson, who has taken it in North Lancashire, Cheshire, 

 Derbyshire, Yorkshire, Lincolnshire and Wales, says " I have never 

 taken P. Agestis, except in localities where the Helianthemum grows." 

 I might multiply these instances, but refrain. They are pretty strong 

 indications that the larva of the southern form finds equally with the 

 northern one a pabulum in this plant. 



George Wailes. 



Douhle-hroodedness of Acherontia Alropos and Notodonta ziczac. — I have defined, 

 in a previous number (Zool. 4902), my interpretation of the expression " single- 

 brooded;" it is " when the cycle of animal life occupies an entire year." I admit that 

 the state of imago, pupa, Sec, ma7/ occur twice in the year in a single-brooded insect, 

 but if all the four states occur twice, then is the species double-brooded. During the 

 past unusually warm season the imago of Acherontia Atropos has appeared at two 

 distinct seasons. Perhaps it always does so : this year there can be no doubt of the 

 fact: these seasons were June and October ; and, moreover, the June moths are un- 

 questionably the parents of the October mollis. Let A (first brood) be a female imago 

 in June; it laid eggs on the potato: the eggs hatched in June, the larva? fed in June, 

 July and August; they became pupse in September, and perfect moths, B (second 

 brood), on the 1st of October. Here then, to all appearance, we have two broods in 

 one year; and if I clearly understand Mr. Gascoyne's papers (Zool. 5826, 6248) this 

 is what he would receive as conclusive evidence that Acherontia Atropos was double- 

 brooded ; but this is not so: the moths of June, 1858, were a portion of a brood which 

 went down in September, 1857; and a portion of their progeny will, in like manner, 

 survive the coming winter, it matters not whether as pupee or perfect insects, and will 



xvi. 3 I 



