GALL-FLIES. 329 



fine the flowing sap within the dimensions of any of the 

 little clustered globes containing the eggs, for it oozes ont 

 from numerous cracks or pores in the pellicle ; which 

 cracks or pores, however, are not large enough to admit a 

 human hair. But this, so far from being a defect in the 

 glutinous pellicle of the bedeguar fly, is, as we shall pre- 

 sently see, of great utility. The sap which issues from each 

 of these pores, instead of being evaporated and lost, shoots 

 out into a reddish-coloured, fibrous bristle. 



It is about half an inch long, and, from the natural ten- 

 dency of the sap of the rose-tree to form prickles, these are 

 all over studded with weak pricklets. The bedeguar, 

 accordingly, when fully formed, has some resemblance, at a 

 little distance, to a tuft of reddish-brown hair or moss stuck 

 upon the branch. Sometimes this tuft is as large as a small 

 apple, and of a rounded but irregular shape ; at other times it 

 is smaller, and in one instance mentioned by Keaumur, only 

 a single egg had been laid on a rose-leaf, and, consequently, 

 only one tuft was produced. Each member of the con- 

 geries is furnished with its own tuft of bristles, arising from 

 the little hollow globe in which the egg or the grub is 

 lodged. 



The prospective wisdom of this curious structure is 

 admirable. The bedeguar grubs live in their cells through 

 the winter, and as their domicile is usually on one of the 

 highest branches, it must be exposed to every severity of 

 the weather. But the close, non-conducting, warm, mossy 

 collection of bristles, wdth which it is surrounded, forms 

 for the soft, tender grubs a snug protection against the 

 winter's cold, till, through the influence of the warmth of 

 the succeeding summer, they undergo their final change 

 into the winged state ; preparatory to which they eat their 

 way with their sharp mandibles through the walls of their 

 little cells, which are now so hard as to be cut with diffi- 

 culty by a knife. (J. R.) 



Another structure, similar in principle, though different 

 in appearance, is very common upon oak-trees, the termi- 

 nation of a branch being selected as best suited for the 

 purpose. This structure is rather larger than a filbert, and 



