vr HETEROCERA NOCTUIDAE 417 



latter Insect attacks a great variety of plants, and has a very 

 wide distribution, being found even in England, where happily 

 it is always a rare Insect. 



In Britain, as well as in parts of Northern Europe, a Xoctuid 

 moth, Charaeas graminis, occasionally increases to an enormous 

 extent : its larva is called the Hill-grub and lives on the grass of 

 pastures, frequently doing great damage in hill-lands. The in- 

 crease of this moth seems to take place after the manner of an 

 epidemic ; a considerable number of years may pass during which 

 it is scarcely seen, and it will then appear in unusual numbers 

 in widely separated localities. This moth lays a large number 

 of eggs, and is not completely nocturnal in habits ; sometimes it 

 may be seen on the wing in great numbers in the hottest sun- 

 shine, and it has been noticed that there is then a great dispro- 

 portion of the sexes, the females being ten or twenty times as 

 numerous as the males. In Australia, the Bugong moth, Agrotis 

 spina, occurs in millions in certain localities in Victoria : this 

 moth hibernates as an imago, and it formerly formed, in this 

 instar, an important article of food with the aborigines. The 

 powers of increase of another Noctuid moth Erastria scitula 

 are of great value. Its habits have been described by 

 Rouzaud. 1 On the shores of the Mediterranean the larva of this 

 little moth lives on a Scale-Insect Lecanium oleae that infests 

 the peach ; and as the moth may have as many as five genera- 

 tions in a year, it commits laudable havoc with the pest. The 

 larva is of remarkable form, very short and convex, with small 

 head, and only two pairs of abdominal feet. The scale of the 

 Lecanium is of larger size than is usual in that group of Insects, 

 and the young larva of the Erastria buries itself, as soon as 

 hatched, in one of the scales ; it destroys successively numerous 

 scales, and after having undergone several moults, it finds itself 

 provided, for the first time, with a spinneret, when, with the aid 

 of its silk, it adds to and adapts a Coccid scale, and thus forms a 

 portable habitation ; this it holds on to by means of the pair of 

 anal claspers, which are of unusual form. The case is afterwards 

 subjected to further alteration, so that it may serve as a protec- 

 tion to the creature when it has changed to a pupa. This moth 

 is said to be free from the attacks of parasites, and if this be the 

 case it is probable that its increase is regulated by the fact that 



1 Insect Life, vi. 1894 p. 6. 

 VOL. VI 2 E 



