the Biology of some British Neitroptera. 537 



third gives the time taken by a larva which passed the 

 winter. There are several broods in the year, one follow- 

 ing immediately upon the other. The food of H. humuli 

 larvae on hazel has been seen to be Myzocallis coryli Gtze. 

 and 31acrosiphum avellanae Schr., besides Psylhd nymphs. 

 As, however, the larva in captivity is not at all fastidious, 

 the exact species of aphid matters little. 



Hemerobius iutescens Fabricius. 



Wing expanse 14-lG mm. Colour pale yellow marked with 

 fuscous. Antennae yellowish, hardly annulated. Fore-wings with 

 a distinct black spot in basal third, between Mg + ^ and Cu^. 

 Venation pale, more or less spotted with blackish. The inner 

 (dorsal) margin of the fore-wing is clouded v/ith brown or greyish, 

 extending into the membrane. The wing is also clouded in the 

 region of the gradate veinlets. 



It is often difficult in the case of females to distinguish 

 this species from Jmm.uli. The fore-wings are, however, 

 less distinctly spotted and more clouded with greyish than 

 in humuli, as a rule, 



H. Iutescens is common from April until October in 

 deciduous woods. It appears to be more common than 

 humuli on beeches. 



Eggs are laid singly in the curled dead margins of leaves, 

 and on the upper or lower faces of living leaves, in the 

 vicinity of aphids. There is no difference observable from 

 the eggs of H. humuli. As hatching approaches, signs of 

 the embryo within are visible. The larva escapes and 

 commences feeding almost immediately on unhatched eggs 

 or aphids. It is at first about 1 mm. long and pale yellow 

 in colour. 



In the second instar, the head and body markings are 

 more easily visible and are the same as in the later larva. 



To give a description of the third-instar larva would 

 be to repeat, to a great extent, that of H. humuli, since 

 Iutescens is very similar. The following trivial differences 

 are noticeable in a typical larva of Iutescens. The central 

 mark of the head extends almost to the anterior margin, 

 and much farther forward than is the case in humuli. The 

 body coloration is less brilliant as a rule, and the white 

 parts more often have a yellowish or brownish tinge. 

 Nevertheless, it is commonly quite impossible to distin- 



