130 INDIRECT INJURIES CAUSED BY INSECTS. 



I have not observed that oats suffer from insects^except from the uni- 

 versal subterranean destroyer of the grasses, the wire-worm, of which 1 

 shall give you a more full account hereafter ; and occasionally from an 

 Aphis. 



Buckwheat {Polygonum fagopyrum), a grain little cultivated with us, 

 except as food for pheasants, but which is an important crop on the Con- 

 tinent on poor sandy soils, is sometimes wholly cut off, by the larvae of a 

 moth {Agrotis tritici), which afterwards devours the rye sown to replace 

 the buckwheat ; and millet, also a considerable continental crop, is occa- 

 sionally much damaged by the larvae of another moth (Botys silaccalis), 

 which, eating into the stem of the plants, causes them to wither and die.^ 



The only important grain that now remains unnoticed is the maize, or 

 Indian corn. Besides the chintz bug-fly, a little beetle^ {Phalcria comuta) 

 appears to devour it ; and it has probably other unrecorded enemies. The 

 Guinea corn of America {Holcus hicolor), as well as other kinds of grain, 

 is, according to Abbott, often much injured by the larva of a moth, 

 {Noctua frugiperda Smith,) which feeds upon the main shoot."' 



Next to grain ^u/se is useful to us, both when cultivated in our gardens 

 and in our fields. PeMs and Leans, which form so material a part of the 

 produce of the farm, are exposed to the attack of a numerous host of 

 insect depredators ; indeed the former, on account of their ravages, is one 

 of the most uncertain of our crops. The animals from which in this 

 country both these plants suffer most are the Aphides, commonly called 

 leaf-lice, but which properly should be denominated plant-lice. As almost 

 every animal has its peculiar louse, so has almost every plant its peculiar 

 plant-louse ; and, next to locusts, these are the greatest enemies of the 



wcx)den floor of the slory above. What was remarkable, as Mr. Raddon communicaied 

 to the Entomological Society (Trans, ii. proc. Ixvii.), was the great depth to which the 

 larvPR had bored in the wood, even through knots filled with turpentine, so as to convert 

 portions of tlie wood-work in places quite inio a honey-comb, and thus to be almost as 

 injurious to the building as lo the corn stored in it. Our first idea was that this boring was 

 simply for the purpose of gnawing off portions of wood with which to form their cocoons 

 before becoming pupae, but the powdery masses hanging from the entrance of the holes 

 had, when viewed under a lens, so completely the appearance of excrement, that we were 

 at last forced to the conclusion, however strange and improbable it may seem, that these 

 larvnp, after eating ad libitum of barley, voluntarily quit it, and actually cat and digest fir- 

 wood, even to the very knots saturated with turpentine. In fact, the great depth to which 

 they bore is inconsistent with the supposition of their object being merely to detach woody 

 fibres as a covering for their cocoons. That their main purpose (whether we suppose the 

 excavated wood to be eaten and digested or not) is to provide a retreat for the larvae, 

 which remain in this state the whole winter, and do not become pupre till spring, is proved 

 by the fact that it is from the mouths of these holes (after every portion of the excrement 

 hanging from them has been swept away, and the whole ceiling thickly lime-washed, as it 

 is every autumn) that the moths emerge by thousands in the month of June, as yearly 

 takes place in Messrs. Hellicar's granaries. The further investigation, which is so evident- 

 ly required, as to the strange anomaly of these larvae seeming to eat and digest wood after 

 devouring as much barley as they choose, I have recommended lo my friend G. H. K. 

 Thwaitc, Esq. of Bristol, whose habits of close observation so well fit him for throwing 

 light on the subject ; and meanwhile it may be here observed, that the facts stated of the 

 great damage done to vessels that bring bones, hoofs, and horns from Brazil, and in one 

 case to a large parcel of cork-wood, by the larva; of Dermestes i'mZ/jj/ims, which, after eating 

 their fill of animal matter, attack wood and cork, seem of an analogous kind to those 

 above mentioned, unless in these instances the wood and cork are merely gnawed, and not 

 eaten and digested. (See Trans. Ent. Soc. Land. ii. proc. Ixviii. j and Shuckard's Ele- 

 ments of Brit. Ent. i. 189.) 



> Kollar on Ins. inj, to Gardeners, kc. 102—110. 



* This insect was taken in maize by Mr. Sparsball of Norwich. 



' Smith's Abbott's Insects of Georgia, I'Jl. 



