INDIRECT BENEFITS DERIVED FROM INSECTS. 149 
of a particular kind of crane-fly with pectinated antenne (Ctenophora*), 
and other insects, which there find an appropriate nutriment; and a 
similar diet is furnished to the grubs of the rose-beetle (Cefonia aurata) by 
the dead leaves and stalks usually to be found in the ant’s nest. Staphy- 
linide, Spheridia, and other Coleoptera, are always found under heaps of 
putrescent vegetables ; and an infinite number are to be met with in de- 
composing fungi, which seem to be a kind of substance intermediate 
between animal and vegetable. The Boleti, in particular, have one genus 
of coleopterous insects appropriated to them, and the Lycoperdons another. 
— Stagnant waters, which would otherwise exhale putrid miasmata, and 
be often the cause of fatal disorders, are purified by the innumerable 
Jarvee of gnats, Ephemera, and other insects which live in them and ab- 
stract from them all the unwholesome part of their contents. This, Linné 
says, will easily appear if any one will make the experiment by filling two 
vessels with putrid water, leaving the larvie in one and taking them out of 
the other; for then he will soon find the water that is full of larve pure 
and without any stench, while that which is deprived of them will continue 
stinking.® 
Benefits equally great are rendered by the wood-destroying insects. 
We indeed, in this country, who find use for ten times more timber than 
we produce, could dispense with their services ; but to estimate them at 
their proper value, as affecting the great system of nature, we should 
transport ourselves to tropical climes, or to those under the temperate 
zones, where millions of acres are covered by one interminable forest. 
How is it that these untrodden regions, where thousands of their giant 
inhabitants fall victims to the slow ravages of time, or the more sudden 
operations of lightning and hurricanes, should yet exhibit none of those 
scenes of ruin and desolation that might have been expected, but are 
always found with the verdant characters of youth and beauty? It is to 
the insect world that this great charge of keeping the habitations of the 
Dryads in perpetual freshness has been committed. A century would 
almost elapse before the removal from the face of nature of the mighty 
ruins of one of the hard-wooded tropical trees, by the mere influence of 
the elements. But how speedy its decomposition when their operations 
are assisted by insects! As soon as a tree is fallen, one tribe attacks its 
bark*, which is often the most indestructible part of it ; and thousands of 
orifices into thé solid trunk are bored by others. The rain thus insinuates 
itself into every part, and the action of heat promotes the decomposition. 
Various fungi now take possession and assist in the process, which is fol- 
lowed up by the incessant attacks of other insects, that feed only upon 
wood in an incipient state of decay. And thus in a few months a mighty 
mass, which seemed inferior in hardness only to iron, is mouldered into 
dust, and its place occupied by younger trees full of life and vigour, The 
1 Curtis, Brit. Ent. t. 5. 
2 Surely Mr. Marsham’s name for this gerus, Boletaria, is much more proper 
than that of Fabricius, Mycetophagus (Agaric-later), since these insects seldom eat 
garies, 
5 (con. Nat. Amen. Ac. ii. 50. Stillingfleet’s Tracts, 122. 
* Maupertuis observes, that in Lapland he saw many birch trees lying on the 
ground, which had probably been there for a very long time, with the bark entire, 
though the wood was decayed, Hence we may probably infer, that in that country 
there are few or none of the bark-boring insects. 
L 3 
