INDIRECT INJURIES CAUSED BY INSECTS. 95 



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

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

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

 Aphis. 



Buckwheat (Potygonum fftgopyrum), 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 occasionally 

 much damaged by the larvas of another moth (Botys silacealis'), which, 

 eating into the stem of the plants, causes them to wither and die. 1 



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

 Indian corn. Besides the chintz bug-fly, a little beetle 2 (Phaleria cornvta) 

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

 Guinea corn of America (Holcus bicolor), as well as other kinds of grain, 

 is, according to Abbot, often much injured by the larva of a moth (Noctua 

 frugiperda Smith), which feeds upon the main shoot. 3 



Next to grain pulse is useful to us, both when cultivated in our gardens 

 and in our fields. Peas and beans, 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 



Society {Trans, ii. proc. Ixvii.), was the great depth to which the larvae had bored 

 in the wood, even through knots filled with turpentine, so as to convert portions of 

 the wood-work in places quite into a honey-comb, and thus to be almost as injurious 

 to the building as to 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 excre- 

 ment, that we were at last forced to the conclusion, however strange and improbable 

 it may seem, that these larvas, after eating ad libitum of barley, voluntarily quit it, 

 and actually eat and digest fir-wood, even to the very knots saturated with turpen- 

 tine. In fact, the great depth to which they bore is inconsistent with the sup- 

 position 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 pupae 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 

 evidently required, as to the strange anomaly of these larvaa seeming to eat and di- 

 gest wood after devouring as much barley as they choose, I have recommended to 

 my friend G. H. K. Thwaite, Esq. of Bristol, whose habits of close observation so 

 well fit him for throwing light on the subject ; and meanwhile it may be here ob- 

 served, 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 

 larvaa of Dermestes vulpinus, 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. : and Shuckard's Elements of Brit. 

 Ent. i. 189.) 



1 Kollar on Ins. inj. to Gardeners, &c. 102110. 



2 This insect was taken in maize by Mr. Sparshall of Norwich. 



3 Smith's Abbott's Insects of Georgia, 191. 



