294 OBSERVATIONS ON INSECTS. 



young leaves that were prematurely forced, as above 

 mentioned,) clusters of minute globules that appear- 

 ed to be eggs. There were also, on the tree, great 

 numbers of aphides, which appeared to have had 

 some share in bringing it into its diseased state ; and 

 also a few of the larvae of what was supposed to be 

 a Hemerobius, preying upon both mites and aphides, 

 empty skins of which were scattered everywhere upon 

 the leaves. 



This mite is no doubt the Icarus telarius of Lin- 

 naeus, so called from a thin filmy web which it spins, 

 and with which it mats the under side of the leaves of 

 the trees it frequents. Such a web I discovered 

 upon the leaves in question ; but the threads of which 

 it is composed are so extremely fine, that, when 

 single, they can be with difficulty perceived, except 

 under a high power of the microscope. The web alone 

 must injure the health of the leaves, independent of 

 the punctures made by the mites themselves, which 

 last were distinctly seen in some instances inclining 

 forward the anterior extremity of their bodies, and 

 plunging their rostrum into the leaf to feed. The 

 mites run upon the threads of their web like spiders, 

 but not very swiftly ; off the threads their motions 

 seem impeded, and upon a smooth surface like glass 

 it is with some difficulty they move at all. 



"When once a tree has become much infested with 

 this parasite, its cure is next to hopeless. In the 

 present instance, the tree had shewn the disease 

 year after year ; and there was nothing to be done, 

 as I was told, but to cut it down, which has since 

 been effected. Some have recommended frequent 



