Insects. 



6177 



better than quote him, even at some length, and at the expense of a 

 little repetition. 



The species of insects," he remarks, " which attack the larger of 

 our domestic quadrupeds [also wild quadrupeds, and even man him- 

 self, — mosquitos to wit, among the great number and variety of them,] 

 may be divided into two chief classes \ first, those which do so in order 

 to obtain a supply of food for their own support; and second^ ihof^e 

 which do so with the object of depositing their eggs in such a position, 

 that the larvae, when hatched from them, wull be certain of finding a 

 proper supply of food derived from some part of the animal, either 

 external or internal." 



In other words, the one class is simply predatory, and the other is 

 parasitic (being predatory only during the larva or maggot phase of 

 existence) ; and it should have been surmised that the tzetze fly, which 

 occasions the sure death of so many cattle in Africa, could not be a 

 bot-producer, as it destroys so large a proportion of the beasts that 

 should furnish a living nidus and support for its progeny. Conse- 

 quently, again we perceive that Bracy Clark must needs be in error 

 in identifying it with the CEstrus or Hypoderma Bovis. 



In loose parlance, both groups might be termed parasitic; but on 

 the principle that the first is so designated, all predacious animals 

 would be parasitic on their victims, the animal kingdom upon the 

 vegetable kingdom (with seeming exceptions only), and the latter upon 

 the mineral kingdom. Perhaps the mildest form of parasitic habit, 

 proprement dit^ is that of the cuckoo or " cow bunting" depositing its 

 egg in the nest of another bird : and about the mildest form of preda- 

 tory habit is that of the creature that robs another of its food ; as the 

 whiteheaded sea eagle {Haliaetus leiicocephalus) of North America, 

 or its counterpart in this country [H, fulviventer)^ making the osprey 

 yield up its captured fish ; or the skua gull (Catarracta) and also the 

 ''frigate-bird" or man-of-war-bird " [Fregata] pursuing ordinary 

 gulls, &c., and forcing them to eject their swallowed prey, which is 

 caught up ere it reaches the water. Certain robbers of the hive may 

 be placed in this category : and the next step is, 1 believe, peculiar to 

 the human animal, in draining the milk of kine, &c. Next follow the 

 multitudinous and varied host of blood-suckers," — including the 

 vampyres (Desmodus) of South America — not the large and more or 

 less frugivorous bats {Phyllostoma, Vampyrus, &c.), which have been 

 erroneously accused of this propensity, but certain species of rather 

 small size, which are especially organised for this particular mode of 

 subsistence, having lancet-like front teeth, no grinders whatever, and 

 XVI. 2 T 



