2 ARKIV FÖR ZOOLOGI. BAND 6. NIO 7. 



an idea of the habitus. Three years låter, in 1856, Letzner 

 [4. p. 98—102], apparently without knowing Hegeer's paper, 

 gives an accurate and good account of the biology. After 

 Letzner we find only short scattered notes on its occurence 

 and biology by Aurivillius, Spångberg, Laboulbéne a. o. 

 [comp. Rupertsberger 10]. 



The material, on which the present paper is based, was 

 collected in August last summer in the South of Fyen, Den- 

 mark. The larvse in great numbers attacked the willows, 

 which are commonly used in that country as hedges along 

 the roads, and were also found on the poplar. 



Metaiuorphosis. 



1. The fullgrcwn larva. 



The fullgrown larva (fig. 7 & 8 Pl. I) attains a length 

 of 3,5 mm. 



The body is flattened dorsoventrally and attains its 

 greatest width in the mesotboracio segment; from thence it 

 tapers gradually towards the narrow and rounded posterior end. 



The larva is of a brownish yellow colour, which is light 

 in the earlier stages, but gradually becomes darker. 



On both the dorsal and ventral side we notice trans- 

 verse dark, blackish spöts, which are arranged in the following 

 way: on the dorsal side (Fig. 8, Pl. I) the spöts are narrrow, 

 irregular streaks, about half as long as the resp. segments 

 and arranged two and two close together on each side of 

 the demarcation line between the segments; there are 9 pairs 

 of them, the first streak on the metathorax, the last on the 

 9th abdominal segment; they increase in length until the 

 2nd abdominal segment, the following 3 pairs are of sub- 

 equal length; further back they dimimish gradually in size^ 

 so that on the anal segment they are small and inconspi- 

 cuous. 



On the ventral side (Fig. 7, Pl. I) the spöts are more 

 or less broad, oval, and, arranged in a median row, one on 

 each segment, from the mesothorax to the 8th abdominal 

 segment; they increase in size towards the 2nd abdominal 

 segment, the following 5 spöts are of subequal size, the two hind- 

 most ones on the contrary are as small as the fchoracic spöts. 



