180 
NATURAL HTSTOEY OF SELBOENE 
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 twenty-seventh, 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 their 
dam coursing round the church in the act of learning to fly, as the first 
broods evidently do. On the thirty-first 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 hippoboscce liirundinis. 
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 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 occur- 
rence 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 third of September. 
LETTEE LIIL 
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 dust-like appearance, on which the 
flies fed eagerly ; and that the shoots and leaves thus aflfected did not 
thrive ; nor did the fruit ripen. To this substance I applied my 
glasses ; but could not discover that it had anything 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 side proceeded a cotton-like substance, 
surrounding a multitude of eggs. This curious and uncommon por- 
duction put me upon recollecting what I have heard and read concerning 
the coccus vitis viniferce of Linnaeus, which, in the south of Europe, 
infests many vines, and is an horrid and loathsome pest. As soon as I 
had tiirned to the accounts given of this insect, I saw at once that it 
swarmed on my vine ; and did not appear to have been at all checked 
by the preceding winter, which had been uncommonly severe. 
l^oi being then at all aware that it had anything to do with England, 
I was much inclined to think that it came from Gibraltar among the 
many boxes and packages of plants and birds which I had formerly 
received from thence ; and especially as the vine infested grew imme- 
