INDIRECT INJURIES CAUSED BY INSECTS. 183 



of Wurm trbkniss (decay caused by worms) ; and in the old 

 liturgies of that country the animal itself is formally men- 

 tioned under its vulgar appellation^ " The Turk." 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 working of their mines, and consequent ruin. At this 

 period these Tomici, when arrived at their perfect state, mi- 

 grated in swarms like bees into Suabia and Franconia. At 

 length, between the years 1784 and 1789, in consequence of 

 a succession of cold and moist seasons, the numbers of this 

 scourge were sensibly diminished. It appeared again, how- 

 ever, 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 at- 

 tacks of the above-mentioned insects, or any other cause ^, it 

 is attended by various beetles, as Cetonia aurata, several Ni- 

 tidulcB and Brachyptera, &c., which prevent it from healing ; 

 and if the bark be any where separated from the wood, a nu- 

 merous 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 sub- 

 ject to injuries from insects ; but these being more out of the 

 reach of observation, 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, 



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, above refen-ed to, 1 noticed in the liquid matter 

 so often seen constantly oozing from the large ulcers in this tree a dipterous 

 larva in considerable 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 Ceratopogon, probably (but I have not the specimens now at hand to 

 compare with his description) C. flavifrons of Guerin {Ann. Soc. Ent. de 

 France, ii. 165,), which he found in a similar situation. 



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