THE NOCTUM 



241 



The moth called the Dark Dagger (Tridens) is hardly to he dis- 

 tinguished from Psi. It is not really anj' darker, and its markings 

 are almost exactly similar ; but the larva is very different. 



Fic. 140.— The Poplak Grey. 



TJic Po2)hir Grey {Acroinjcta uwrjacrjiJKda) 



This is also a very common moth, to he found in all the southern 

 and midland counties, wherever poplars abound, during June and 

 July. 



Its fore wings are gi'ej', marbled with a very dark grey. A little 

 inside the middle of these wings, near the costa, is a round spot 

 with a dark centre. This spot is ^^^ 

 represented in a large number of 

 the NoctiKT, and is known as the 

 orbicular. It will be observed 

 that in the present species it is 

 very distinct. 



The caterpillar is dark gi'ej^ 

 with a line of black dots down the 

 back ; and it has a number of 



little warts, bearing hairs. On the back of the eleventh segment 

 is a rather large pale spot. It feeds during August on various 

 species of poplar, and changes to a chrysalis in a crevice of the 

 bark. 



The Figure of FAgld {DiJoba ccj^ridcoccpliala) 



The fore wings are brownish grey. Near the middle of the 

 wing, but nearer the costa than the inner margin, are two whitish 

 spots that resemble the figure 8. The hind wings are dull brownish 

 grey, with darker wing rays, and a 

 dark spot near the centre. 



This moth is common in all parts, 

 and flies during SeptemV)er. 



The caterpillar emerges from the 

 egg in spring, and is fully grown in 

 May or June. It is of a very pale 

 colour — yellowish or greenish — with a 

 broad and broken yellow stripe down 

 the back, and a bluish or greenish 



stripe on each side. Its head is blue (hence the specific name) 

 witii two black spots. It feeds on the hawthorn {Cratiegus oxij- 



Fig. 141.— The Figuee 

 OF Eight. 



