208 INDIRECT INJURIES CAUSED BY INSECTS. 



vellers and people abroad were very much annoyed by 

 their continual flying in their faces ; and in a short time 

 the leaves of all the trees for some miles round were so 

 totally consumed by them, that at Midsummer the coun- 

 try wore the aspect of the depth of winter 8 . 



But the criminals to whom it is principally owing that 

 our groves are sometimes stripped of the green robe of 

 summer, are the various tribes of Lepidoptera, especially 

 the night-fliers or moths, myriads of whose caterpillars, in 

 certain seasons, despoil whole districts of their beauty, 

 and our walks of all their pleasure. In 1731 the oaks 

 in France were terribly devastated by the larva of Hy- 

 pogymna dispar b , and in 1797 many of the pine forests 



a Philos. Trans, xix. 741. 



b Reaum. i. 387. These larvae were so extremely numerous in 

 1826 on the limes of the Alice Verte at Brussels, that many of the 

 trees of that noble avenue, though of great age, were nearly deprived 

 of their leaves, and afforded little of the shade which the unusual 

 heat of the summer so urgently required. The moths which in au- 

 tumn proceeded from them, when in motion towards night, swarmed 

 like bees, and subsequently on the trunk of every tree might be seen 

 scores of females depositing their down-covered patch of eggs. In 

 the Park they were also very abundant j and it may be safely asserted 

 that if one half of the eggs deposited were to be hatched, in 1827 

 scarcely a leaf would remain in either of these favourite places of 

 public resort. Happily, however, this calamity seems likely to be pre- 

 vented. Of the vast number of patches of eggs which I saw on al- 

 most every tree in the park about the end of September, I could 

 two months afterwards to my no small surprise, discover scarcely one, 

 though the singularity of the fact made me examine closely. For 

 their disappearance 1 have no doubt the inhabitants of Brussels are 

 indebted to the tit-mouse (Parus*), the tree-creeper (Certhia fami- 

 liaris), and other small birds known to derive part of their food from 

 the eggs of insects, and which abound in the park, where they may 

 be often seen running up and down the trunks of the trees, at once 

 providing their own food and rendering a service to man, which all 

 his powers would be inadequate completely to effect. 



Reaumur (ii. 106) in certain seasons found these patches of eggs 



