420 Insect Architecture. 



The most remarkable instance of this, however, which we 

 have seen, occurs on the leaves of the elm, and is caused 

 by the Aphis ulmi. The edge of an elm-leaf inhabited by 

 those aphides is rolled up in an elegant convoluted form, 

 very much like a spiral shell ; and in the embowered chamber 

 thus formed the insects are secure from rain, wind, and 

 partially from the depredations of carnivorous insects. One 

 of their greatest enemies, the lady-bird (Coccinella), seldom 

 ventures, as we have remarked, into concealed corners except 

 in cold weather, and contrives to find food enough among 

 the aphides which feed openly and unprotected, such as the 

 zebra aphides of the alder (Aphides sambuci}. The grubs, 

 however, of the lady-bird, and also those of the aphidivorous 

 flies (SyrpTii), may be found prying into the most secret 

 recesses of a leaf to prey upon the inhabitants, whose slow 

 movements disqualify them from effecting an escape. (J. E.) 



The effect of the puncture of aphides on growing plants is 

 strikingly illustrated in the shoots of the lime-tree and 

 several other plants, which become bent and contorted on 

 the side attacked by the insects, in the same way that a shoot 

 might warp by the loss of its juices on the side exposed to a 

 brisk fire. The curvings thus effected become very advanta- 

 geous to the insects, for the leaves sprouting from the twig, 

 which naturally grow at a distance from each other, are 

 brought close together in a bunch, forming a kind of nose- 

 gay, that conceals all the colour of the sprig, as well as the 

 insects which are embowered under it, protecting them 

 against the rain and the sun, and at the same time hiding them 

 from observation. It is only requisite, however, where 

 they have formed bowers of this description, to raise the 

 leaves, in order to see the little colony of the aphides, or 

 the remains of those habitations which they have abandoned. 

 We have sometimes observed sprigs of the lime-tree, of a 

 thumb's thickness, portions of which resembled spiral 

 screws ; but we could not certainly have assigned the true 

 cause for this twisting, had we not been acquainted with the 

 manner in which aphides contort the young shoots of this 



