44 THE ENTOMOLOGIST. 



the dates for these would have been a little earlier. The two 

 series of moths were easily distinguishable, both by colour and 

 by the direction of the median line on the fore wings. The 

 alder-bred moths were silvery-grey, varying in depth, but never 

 approaching brown, with the median line bent at a right angle 

 about a fourth of the distance from the costa. Those bred from 

 whitethorn were brown, with the median line irregularly waved 

 and dentated. 



From September 30th to October 5th I took a few moths in 

 the alder plantation, all resembling those bred from alder. I 

 disturbed tbem by jarring the trunks of the trees, but they often 

 flew from one tree to another, without descending low enough 

 for the net. None were seen at rest on the trees, and no females 

 were taken. An attempt to hunt the moths by lantern light 

 proved a failure. 



I submitted all these specimens to the inspection of Mr. 

 Prout, and his reply satisfied me that I had two distinct forms, 

 the alder-bred specimens being autumnata, and the whitethorn- 

 bred dilutata. In 1899 I did not keep any larvas, except a few 

 found on birch (which I failed to rear), and a part of a small 

 brood of autumnata from an accidental pairing in captivity. 

 These began to hatch March 22nd, and took to whitethorn so 

 readily that I never offered them any other food. I reared ten 

 specimens, all closely resembling the parents. 



In 1900, I found the larvae fairly common in another alder 

 plantation, near the former one, consisting of lower trees, and 

 therefore easier to work. The moths bred in this year show a 

 much wider range of variation, some being very dark, like the 

 specimens figured by Mr. Prout in Entom. xxxiii. PL I., figs. 12 

 to 15, while one resembled fig. 5 on the same plate (var. sa7id- 

 hergi). The most interesting circumstance was that I bred an 

 unmistakable dilutata from the alder-fed larvae ; also a yellowish 

 specimen, which Mr. Prout refers to his var. christyi of dilutata. 

 The larvae from the two plantations were not kept separate, and 

 I suspect that these larvae came from the new plantation, as I 

 also captured a few dilutata in this plantation. In the original 

 plantation I had this year a curious instance of the way in 

 which the two forms keep within their respective bounds. From 

 a small hazel tree growing in the midst of the alders I beat a 

 few larvae, one with conspicuous purple marks. I kept these 

 separate, and the moths turned out to be typical dilutata. I 

 also reared this year two autumnata from larvae taken on birch, 

 but in the midst of the alder plantation. Of these two, one was 

 the lightest and the other almost the darkest I have ever bred. 

 I have never known autumnata to stray away from the alder 

 plantations. All the moths taken at street-lamps in the town, 

 and in other parts of the district, are most obviously dilutata. 

 A few specimens which were taken at a short distance from 

 the autumnata localities, and which I once thought might be 



