INSECTS APHIS, SCALES 189 



The life-history of the aphis is very remarkable. Their extraordinary 

 abundance is due to their peculiar method of reproduction. In the autumn 

 numerous eggs are laid in the crevices of bark, which hatch the next spring, 

 producing wingless females. These females actually produce young like 

 themselves, no male being necessary ; and this remarkable reproduction goes 

 on for several generations, the young aphis herself becoming a mother in 

 ten or fifteen days. Hence in a few weeks the offspring of a single individual 

 become very numerous. Some of the young aphides of these broods have 

 two pairs of wings : these are usually females. In the autumn, both males 

 and females are born, and these pair, the fertilized eggs which ensue being 

 those which will hatch out the next spring. 



Many insects feed on the aphides, and are therefore friends of the gardener ; 

 especially Wasps, Lady-birds (larvae and imagoes), the larvae of the Lacewing- 

 fly and of Hover-flies. 



THE SCALE INSECTS AND "MEALY BUGS" (Cocctda) 



are very small, but many are most injurious to plants. The males have long 

 antennae and a pair of wings ; the females are slow-moving, grub-like creatures. 

 The best known is the Mussel Scale, or BARK-LOUSE, found on apple trees. 

 Another is the Brown Scale of the gooseberry and currant trees, the male of 

 which has not yet been discovered. The female is unable to move long 

 before she lays eggs, owing to her bulk ; and as she lays, her under surface 

 shrinks until she assumes a sort of dish-cover appearance, under which are 

 hundreds of whitish eggs. She dies hi this position, her dead body, the so- 

 called scale, acting as a protection to the eggs, and for a short period to the 

 larvae. 



Order XL ANOPLURA. 



The True Lice. These are wingless, possibly having lost their wings and 

 become simplified through their parasitic habits. They possess flat bodies, 

 legs furnished with grasping claws, and a sucking beak provided with a circle 

 of hooks near the end. The eggs known as " nits " are pear shaped, and are 

 attached to hairs, feathers, and the like. 



Order XII. NEUROPTERA. 



ALDER-FLIES, ANT-LIONS (not found in England), 

 LACEWINGS, AND OTHERS. 



Alder-flies (Sialida), well known to the angler, are slow and heavy-flying 

 insects, distinguished from Caddis-flies by the fact that the wings are not 

 folded longitudinally when at rest. They lay their eggs in clusters on the 

 leaves or stems of aquatic plants, and the larvae when hatched enter the water, 



