270 SWIFTS. 



the first day of August, all save one pair, which in two or 

 three days was reduced to a single bird. The perseverance 

 of this individual made me suspect that the strongest of 

 motives, that of an attachment to her young, could alone 

 occasion so late a stay. I watched, therefore, till the 24th 

 of August, and then discovered that, under the eaves of the 

 church, she attended upon two young, which were fledged, 

 and now put out their white chins from a crevice. These 

 remained till the 27th, looking more alert every day, and 

 seeming to long to be on the wing. After this day, they 

 were missing at once ; nor could I ever observe them with 

 with their dam coursing round the church in the act of learn- 

 ing to fly, as the first broods evidently do. On the 31st, 

 I caused the eaves to be searched ; but we found in the nest 

 only two callow, dead, stinking swifts, on which a second nest 

 had been formed. This double nest was full of the black 

 shining cases of the Jiippoboscce hirundinis. 



The following remarks on this unusual incident are obvious. 

 The first is, that though it may be disagreeable to swifts to 

 remain beyond the beginning of August, yet that they can 

 subsist longer is undeniable. The second is, that this uncom- 

 mon 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. 



LETTEE XCYII. 



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, grow- 

 ing on the walls of my house, was covered in the autumn 

 with a black, dust-like appearance, on which the flies fed 



