140 INDIRECT INJURIES CAUSED BY INSECTS. 



devours the grain when laid up in the granary. This fly 

 deposits several eggs, perhaps twenty or thirty, on a single 

 grain; but as one grain only is to be the portion of one 

 larva, they disperse when hatched, each selecting one for 

 itself, which it enters from without at a place more tender 

 than the rest; and this single grain furnishes a sufficient 

 supply of food to support the caterpillar till it is ready to 

 assume the pupa. Concealed within this contracted habita- 

 tion, the little animal does nothing that may betray it to the 

 watchful eye of man, not even ejecting its excrements from 

 its habitation ; so that there may be millions within a heap 

 of corn, where you would not suspect there was one.^ 



1 Act. Stockh. 1750. 128. Reaum. ii. 480, &c. Barley, like wheat, and 

 indeed all white corn, is much injured in the granaries of the corn-dealer by the 

 larvae of the little moth ( Tinea granella L.) the wolf of Leeuwenhoek before re- 

 ferred to. On visiting those of Messrs. Hellicar, Bristol, in October, 1837, with 

 my friend W. Raddon, Esq., we found the barley lying on the floors covered 

 with a gauze-like tissue formed of the fine silken threads spun by the larvje in 

 traversing its surface, on recently quitting it for the purpose of undergoing their 

 metamorphosis in the ceiling of the granary, formed of the joists and wooden 

 floor of the story above. What was remarkable, as Mr. Raddon communicated 

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

 which the larvse had bored in the wood, even through knots filled with turpen- 

 tine, 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 excrement, that we were at last 

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

 these larvae, after eating ad libitum of barley, voluntarily quit it, and actually eat 

 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 pupee till spring, is proved by the 

 fact that it is from the mouths of these holes (after every portion of the ex- 

 crement 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 larvae seeming to eat and digest wood after devouring as much barley as 

 they choose, I have recommended to my friend G. H. K. Thwaite, Esq. of 

 Bi'istol, 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 larvae of Dermestes vulpi- 

 nuft, 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. 

 Loud. ii. proc. Ixviii. ; and Shuckard's Elements of Brit. Ent. i. 189.) 



