'Retrospective Criticism, 677 



on his own authority, as facts in natural history ; even though, as in the pre- 

 sent instance, the point he contends for involves the necessity of proving 

 a negative. I am. Sir, yours, &c. — W. T. Bree. Allesley Rectory ^ June 26. 

 1832. 



Effects of the Swallow Tick {Hippobosca Hirundinis L.) on the Swallow 

 Tribe (Hirundines), — Sir, Thefact related by your correspondent O. (p. 203.), 

 of a swift having been killed by flying against a wall at Hastings, and that 

 mentioned by J. D. (p. 204.), of the same bird, and other ifirundines, hav- 

 ing been sometimes found alive on the ground, do not appear to me to be 

 sufficiently accounted for on the supposition of the birds having been 

 reduced to extremities by the Hippobosca i/irundinis, with which they might 

 have been infested. In the first place, there is no evidence that the swift at 

 Hastings was so infested. O. speaks of " several small reddish insects " run- 

 ning about his hand at the time he held the bird. These could hardly have 

 been the Hippoboscai/irundinis, which is nearly, ifnot quite, as large asasheep 

 tick (which it somewhat resembles), and of a dirty greenish colour. But, 

 secondly, if the fact recorded by O. is to be attributed to the torture pro- 

 duced by the swallow tick, would not such catastrophes be of more fre- 

 quent occurrence ? Our British ^irundines are, I believe, very generally 

 infested with the Hippobosca. On the accidental fall of a martin's nest, 

 during the breeding season, I have seldom failed to find it swarming with 

 the parasites. When swifts have been wantonly and barbarously shot in 

 sport, I have more than once found, upon examination, five or six, or 

 more, Hippoboscae " playing at hide and seek very dexterously among the 

 feathers of the bird," as J. D. so descriptively expresses it ; and yet the 

 swifts, up to the moment of their meeting their untimely fate, were as 

 active and vigorous on the wing as usual, and apparently in full enjoyment 

 of all the pleasures of life. In truth, brute animals seem to be far less 

 incommoded by the vermin with which they are infested, than we should 

 at first suppose. And this fact, if fact it be, may be regarded as among 

 the wise provisions of a beneficent Creator ; seeing, as we do, how almost 

 universally animals of whatever kind are subject to their peculiar parasites, 

 of which they have not the power to rid themselves. Butterflies appear 

 to me, though Professor Rennie is of a contrary opinion (see Insect Mis^ 

 cellanieSy p. 28.), to sport about as usual, totally disregarding the swarms 

 of ^^cari (?) which adhere to them in clusters (see p. 336.). Hippobosca 

 ^irundinis is, indeed, an insect of moment and formidable size, as compared 

 with that of the swift or martin on which it preys ; and yet, as already 

 said, these birds, so far as we can judge, appear to enjoy themselves, with- 

 out being incommoded by the parasite. Some other solution, therefore, I 

 think, should be sought of O.'s problem, than the one proposed, though I 

 am not prepared to suggest any that may be more satisfactory. 



Swifts, I am told (though 1 never witnessed the fact), will sometimes 

 fight with each other, and in such cases the contending parties are occa- 

 sionally brought to the ground, and have been found so circumstanced, 

 and with the claws of each mutually clasped into those of the other. 

 J. D.'s swift, discovered among the " longish grass in a village churchyard,'* 

 might possibly have been one of these pugnacious individuals. I once re- 

 collect to have caught a swallow {H. rustica) alive on the ground (and 

 have known the species caught by others) : on being released from the 

 hand, the bird flew away brisk and vigorous. Such captures, perhaps, 

 might be owing to some unusual fatigue or exertion which the birds had 

 undergone, or to accidental temporary injury. If I rightly remember, the 

 swallow in the instance above alluded to, appeared to be asleep at the time 

 it was caught, though the circumstance occurred in the daytime. Yours, 

 &c. — W. T. Bree. Allesley Rectory, March 8. 1832. 



The Angler's Jlfuseiiviy so far as I am enabled to judge by your notice of its 



X X 3 



