Leaf-Rotting Aphides. 



419 



insects, both from the weather and from depredators. That 

 there is design in it appears from the circumstance of the 

 aphides crowding into the embowering vault which they 

 have formed ; and we are not quite certain whether they do 

 not puncture certain parts of the leaf for the very purpose 

 of making it arch over them ; at least, in many cases, such as 

 that of the hop-fly (Aphis liumuli), though the insects are in 

 countless numbers, no arching of the leaves follows. The 

 rose-plant louse, again (Apliis rosce), sometimes arches the 

 leaves, but more frequently gets under the protecting folds of 

 the half-expanded leaf-buds. (J. E.) 



Leaf of the Currant-bush, bulged out by the Aphis ribis. 



One of the most common instances of what we mean 

 occurs on the leaves of the currant-bush, which may often 

 be observed raised up into irregular bulgings, of a reddish- 

 brown colour. On examining the under side of such a leaf 

 there will be seen a crowd of small insects, some with and 

 some without wings, which are the Aphides ribis in their 

 different stages, feeding securely and socially on the juices of 

 the leaf. 



