230 ANIMAL INTELLIGENCE. 



sembles analogous instances which have been mentioned 

 in the case of spiders. 



Dipterous Insects, 



The gad-fly, whose eggs are hatched out in the intes- 

 tines of the horse, exhibits a singular refinement of instinct 

 in depositing them upon those parts of the horse which 

 the animal is most likely to lick. For, according to 

 Bingley and other writers, *the inside of the knee is the 

 part on which these flies principally deposit their eggs ; 

 and next to this they fix them upon the sides, and the 

 back part of the shoulder; but almost always in places 

 liable to be licked by the tongue.' The female fly deposits 

 her eggs while on the wing, or at least scarcely appears to 

 settle when she extends her ovidepositor to touch the 

 horse. She lays only a single egg at a time — flying away 

 a short distance after having deposited one in order to 

 prepare another, and so on. 



The following anecdote, which I quote from Jesse, 

 seems to indicate no small degree of intelligence on the 

 part of the common house-fly — intelligence, for instance, 

 the same both in kind and degree as that which was dis- 

 played by Sir John Lubbock's pet wasp already mentioned : 



Slingsby, the celebrated opera dancer, resided in the large 

 house in Cross-deep, Twickenham, next to Sir Wathen Waller's, 

 looking down the river. He was fond of the study of natural 

 history, and particularly of insects, and he once tried to tame 

 some house-flies, and preserve them in a state of activity through 

 the winter. For this purpose, quite at the latter end of autumn, 

 and when they were becoming almost helpless, he selected four 

 from off his breakfast-table, put them upon a large handful of 

 cotton, and placed it in one corner of the window nearest the 

 fireplace. Not long afterwards the weather became so cold 

 that all flies disappeared except these four, which constantly 

 left their bed of cotton at his breakfast-time, came and fed at 

 the table, and then returned to their home. This continued 

 for a short time, when three of them became lifeless in their 

 shelter, and only one came down. This one Slingsby had 

 trained to feed upon his thumb-nail, by placing on it some moist 

 sugar mixed with a little butter. Although there had been at 

 intervals several days of sharp frost, the fly never missed taking 

 his daily meal in this way till after Christmas, when, his kind 



