152 INDIRECT INJURIES CAUSED BY INSECTS. 



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 country wore the aspect of the 

 depth of winter.^ 



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 nightfliers or moths, myriads of whose cater- 

 pillars, in certain seasons, despoil whole districts of their beauty, and our 

 walks of all their pleasure. Some of these, like the cockchafers, or the 

 caterpillars of Clisiocampa neustria, Porthesia chrysori-haa, &£c. before 

 mentioned, as attacking most fruit-trees, are also general feeders on forest 

 trees, though some of the species usually prefer particular kinds when 

 accessible. Thus in 1731 the oaks of France were terribly devastated 

 by the larva of Hypogymna disyai^ ; as are often those of Germany by 

 that of Cnethocampa proccssionea ; and those of England by the leaf- 

 rolling caterpillar of the pretty little green moth Tortrix viridana. Our 

 elms have their leaves frequently drilled into holes by the little jumping 

 weevil, Orchestes fagi, and the beech, alder, &c., are partially disfigured 

 by other species of this saltatorial tribe. In France, however, the elms 

 sustain a much more serious injury from the larva of another larger beetle 

 {Galleruca calmariensis) , the leaves being sometimes so covered with them, 

 and rendered so brown, as to have the appearance of having been struck 

 by lightning, as was the case with the fine promenades of Rouen, when I 

 was there in 1836. Cheimatobia brumata is likewise a fearful enemy to 

 the foliage of almost every kind of tree.^ The woods in certain provinces 

 of North America are in some years entirely stripped by the caterpillar 

 of another moth, which eats all kinds of leaves. This happening at a 

 time of the year when the heat is most excessive, is attended by fatal con- 

 sequences ; for, being deprived of the shelter of their foliage, whole for- 

 ests are sometimes entirely dried up and ruined.^ The brown tail moth, 

 before alluded to, which occasionally bares our hawthorn hedges, has been 

 rendered famous by the alarm it caused to the inhabitants of the vicinity 



» Philos. Trans, xix. 741. 



* Reaum. i. 387. These larvsB were so extremely numerous in 1826 on the lines of the 

 All^ 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 autumn 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 ihey were also very abundant ; 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 favorite places of public resort. Happily, however, this calamity was prevented by 

 natural means. Of the vast number of patches of eggs which I saw on almost 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 I have no doubt the inhabitants of Brussels are indebted to the tit- 

 mouse {Parus), the tree-creeper (Certhia familiaris), 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 so numerous, that m 

 the Bois de Boulogne there was scarcely an oak, the under side of the branches of which 

 were not covered by them for an extent of seven or eight feet. He informs us that the eggs 

 are not hatched till the following spring. 



3 De Geer, ii. 452. * Kalm's Travels, ii. 7. 



