OF SELBORNE. 303 



on which a second nest had been formed. This double 

 nest was full of the black shining cases of the Hippo- 

 bosca Hirundinis. 



The following remarks on this unusual incident are 

 obvious. The first is, that though it may be disagree- 

 able to swifts to remain beyond the beginning of August, 

 yet that they can subsist longer is undeniable. The 

 second is, that this uncommon event, as it. was owing 

 to the loss of the first brood, so it corroborates my former 

 remark, that swifts breed regularly but once; since, was 

 the contrary the case, the occurrence above could neither 

 be new nor rare. 



P. S. One swift was seen at Lyndon, in the county of 

 Rutland, in 1782, so late as the 3rd of September. 



LETTER LIII. 



TO THE SAME. 



As I have sometimes known you make inquiries about 

 several kinds of insects, I shall here send you an 

 account of one sort which I little expected to have 

 found in this kingdom. I had often observed that one 

 particular part of a vine growing on the walls of my 

 house was covered in the autumn with a black, dustlike 

 appearance, on w r hich the flies fed eagerly; and that 

 the shoots and leaves thus affected did not thrive ; nor 

 did the fruit ripen. To this substance I applied my 

 glasses ; but could not discover that it had any thing to 

 do with animal life, as I at first expected : but, upon a 

 closer examination behind the larger boughs, we were 

 surprised to find that they were coated over with husky 

 shells, from whose sides proceeded a cottonlike sub- 

 stance, surrounding a multitude of eggs. This curious 

 and uncommon production put me upon recollecting 

 what I have heard and read concerning the Coccus Vitis 



