Insects, 



6281 



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

 remarl<able 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 1841 (Zool. 348), on the occurrence on the Polj^ommati 

 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 1 take my finest specimens, and where indeed 

 I caught the curious variety you allude to (mentioned above), 1 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), luy 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, &c., mai/ occur twice in the year in a single- brooded insecf, 

 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 moths. 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 pupa3 in September, and perfect moths, B (sccoiul 

 brood), on the Jst 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 J une, 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 pup® or perfect insects, and will 



XVI. 3 I 



