398 PREDACIOUS AND PARASITIC 



Aphidivorous larvae belong. The labium appears to be firmly 

 united to the lower portion of the head, and no representative of 

 the ligula foreshadows the elaborate mouth-organs of the perfect 

 insect. This peculiar construction is the more remarkable, as in 

 other sections of the Neuroptera, in which the larvae, though of 

 different habits, present many points of resemblance to those of 

 He7nerobiincB, the victim is likewise seized by a pair of formidable 

 forceps, but is conveyed to the month to be devoured. So far as 

 I have myself observed, the absence of mouth in the larvae coin- 

 cides with certain features of the ligula in the imago (which will be 

 illustrated), but I am scarcely able to assert this as a general fact. 



The Tarsus of the Larva. 



Another noticeable feature in the species illustrated on PL 

 XVIII. is the entire absence of the elongated extension of the 

 tarsus, carrying at its extension the pulvillus, which is so strongly 

 developed in the larva of Chrysopa. In the Hemerobius larva 

 the suctorial pad is situated immediately at the base of the claws, 

 but although thus much less obvious, it appears to have very con- 

 siderable adhesive power, as is evidenced by its ability to climb 

 vertical glass surfaces when fully fed. The larva of C. Perla 

 during the latter part of its existence seems quite unable to adhere 

 to such a surface for a much greater height than about twice its 

 own length, when it usually falls back and regains its feet with a 

 struggle. The length of the slender articulation bearing the suc- 

 torial organ in the latter larvae probably has much to do with the 

 difference, as the leverage must greatly weaken the power of 

 adhesion. 



The Wings. 



The Neuroptera Planipennia derive their sectional designation 

 from the flat and broad expanse of the wings, which, especially in 

 the typical genus, Chrysopa^ are of great size, and in many species 

 assume a shape approximating to that of a parallelogram. The 

 hind wings are never larger than the fore wings, but in many of the 

 genera are equal in size and similar in shape and venation. They 

 are not, as in the Hymenoptera, supplied with wing-hooks, but 

 each pair of wings is propelled independently by its own muscles, 



