INSECT SUCKERS AND BITERS. 205 
fly (Syrphidcd) glide about on the stems (see g, Fig. 
69), seizing the aphides in their mouths, sucking out 
their juicy bodies, and dropping the empty skins by 
hundreds. 
And now if once your eyes are open to see these 
tiny juice-suckers, you may find numbers of different 
kinds living their little lives in the fresh country air. 
Have you never picked up an apple-leaf or elm- 
leaf covered with something looking like tufts of 
white cotton, so sticky that you cannot clear your 
fingers of it ? If so, look carefully at it next time 
you find it, and under each white tuft you will see 
an insect struggling along which is like a rose-aphis, 
only without the little tubes on its back. In fact 
this fluffy stuff is a kind of wax which oozes out 
with the sweet liquid all over the body of the insect, 
protecting it from the sun and from enemies as it 
feeds, and making it look like a lady in a feathery 
white ball dress. Some species*" of these fluff-covered 
aphides fasten on to the stems of apple-trees, and 
have been known entirely to destroy them. Then, 
again, there are others which eat their way into the 
leaves of trees, making rosy bladders upon them, 
while others attack the wheat or the hops. In mild 
seasons, when these insects increase rapidly, they have 
been known to destroy a whole hop-harvest. 
Nor are the aphides the only plant-suckers. Look 
at the bushes in summer and you cannot fail to see 
little clusters of froth here and there (Fig. 70), known 
as cuckoo-spit, because they first appear at the time 
when the cuckoo sings. Move this froth carefully, 
and in the middle of it you will find the cuckoo-spit 
* Alyzoxyle mali and Eriosoma lanigerum. 
