Insects and their world 



the Bed Bugs (Cimicidae). Others Hve in the fur of bats, and suck their 

 blood. 



Water-bugs (Fig. 19) again fall into two groups: the 'skaters', which run 

 about on the surface film, and the true water-bugs. The skaters are pro- 

 tected from sinking by having a covering of water-repelling hairs; they 

 feed on less fortunate insects, not so protected, which fall in and are 

 wetted and trapped. 



The true water-bugs still need air to breathe, and so when they dive 

 they carry with them a small bubble. They often have the legs specially 

 modified for swimming (see Figs. 51a, c, e). Water-boatmen (Corixidae) 

 eat algae and small animalcules, while water-scorpions (Nepidae) and 

 back-swimmers (Notonectidae) are carnivorous and fierce. The last may 

 'bite' if they are carelessly handled. 



Homoptera (Figs. 13, 20, 27) include aphids (plant lice), the whitefly 

 of greenhouses, scale insects, and a variety of soft-bodied, plant-feeding 

 bugs. The frog-hoppers, or spittlebugs insects (Cercopidae) and the 

 related leaf-hoppers (Cicadellidae) belong here, as well as the cicadas 

 and lantern-flies, which flourish best in the tropics. 



Aphids are well-known garden pests, and are even more important to 

 the commercial grower because in the course of feeding on one plant and 

 then on another, they carry the viruses of several dozen troublesome 

 diseases of crops. The scale-insects have two-winged males, like small 

 flies, but the females are without wings, and remain stationary on the 

 plant. Often the female is covered and protected by a waxy or resinous 

 'scale', from which these insects get their name. Some are serious pests 

 of fruit crops; on the other hand, the scales of an Indian coccid produce 

 lac, from which shellac is made, and another coccid provides cochineal. 



Division: Endopterygota 



21. Neuroptera (together with Megaloptera: North America 350; world 

 4700) 



Lacewings; ant-lions (Figs. 18, 26, 28). The green lacewing (Chrysopa) 

 is a beautiful fragile insect, with golden eyes, and some species come into 

 houses at night. The brown lacewings (Hemerobiidae) are smaller and 

 more sombrely coloured. Larvae of lacewings prey on aphids and other 

 plant-feeding insects, piercing and sucking by means of grooved man- 

 dibles. Adult lacewings are carnivorous, and so are the adults of the related 

 family Mantispidae, which have powerfully developed fore-legs like a 

 mantis. 



The ant-lions (Myrmeleontidae) have a remarkably aggressive and 

 powerful larva, which lies at the bottom of a conical pit in the dust, and 

 catches ants and other insects when they slide down into it. 



22. Megaloptera (for numbers see above) 



Alderjiies; snakefiies (Fig. 30). Closely related to Neuroptera and some- 

 times merged with them. The alderflies are fairly large, sluggish insects. 



16 



