124 INDIRECT INJURIES CAUSED BY INSECTS. 
This pest was particularly prevalent and caused incalculable mischief, about 
the year 1665. In the beginning of the last century it again showed itself 
in the Hartz forests —it re-appeared in 1757, redoubled its injuries in 
1769, and arrived at its height in 1783, when the number of trees destroyed 
by it in the above forests alone was calculated at a million and a half, 
and the inhabitants were threatened with a total suspension of the work- 
ing of their mines, and consequent ruin. At this period these Zomici, 
when arrived at their perfect state, migrated in swarms like bees into Suabia 
and Franconia. At length, between the years 1784 and 1789, in conse- 
quence of a succession of cold and moist seasons, the numbers of this 
scourge were sensibly diminished. It appeared again, however, in 1790 ; 
and so late as 1796 there was great reason to fear for the few fir-trees that 
were left.} 
When the sap flows from a tree in consequence of the attacks of the 
above-mentioned insects, or any other cause”, it is attended by various 
beetles, as Cetonia aurata, several Nitidule and Brachyptera, &c., which 
prevent it from healing ; and if the bark be anywhere separated from the 
wood, a numerous army of wood-lice, earwigs, spiders, field-bugs, and 
similar subcortical insects take their station there, and prevent a re- 
union. 
The seeds of forest as well as of fruit-trees are doubtless subject to 
injuries from insects ; but these being more out of the reach of observa- 
tion, have not been much noticed. Acorns, however, a considerable article 
with nurserymen, are said to have both a moth and a beetle that prey upon 
them ; and, what is remarkable, though sometimes one larva of each is 
found in the same acorn, yet two of either kind are never to be met with 
together. The beetle is probably the Curculio (Balaninus) glandium of 
Mr. Marsham, and is nearly related to the species whose grub inhabits the 
nut, 
Having now conducted you round, and exhibited to you the melancholy 
proofs of the universal dominion of insects over our yegetabie treasures 
while growing or endued with the principle of vitality, in their separate 
departments, I must next introduce you to a pest worse than all put together, 
which indiscriminately attacks and destroys every vegetable substance that 
the earth produces, and which, wherever it prevails, carries famine, pesti- 
lence, and death in its train. Happily for this country — and we cannot 
be too thankful for the privileze — we know this scourge of nations only 
by report. The name of Locust, which has been such a sound of horror in 
other countries, here only suggests an object of interesting inquiry. But 
the ravages of locusts are so copious a theme that they merit to be con- 
sidered in a separate letter. 
Iam, &e. 
1 Wilhelm’s Recreations from Nat. Hist., quoted by Latreille, Hist. Nat. xi, 194. 
2 While attending to the Scolyti infesting the common elm during the tour in 
the north of France in 1836, aboye referred to, I noticed in the liquid matter so often 
seen constantly oozing from the large ulcers in this tree, a dipterous larva in con- 
siderable numbers, of which this exudation is evidently the natural food; and having 
bred some of them, they produced very minute gnat-like flies, of the genus Cerato- 
pogon, probably (but I have not the specimens now at hand to compare with his 
description) C. flavifrons of Guérin (Ann. Soc. Lnt. de France, ii, 165.), which he 
found in a similar situation, 
5 Reaum. ii, 502. 
