THE CANADIAN ENTOMOLOGIST. 217 



EDITORIAL SUMMARY. 



How do Parasitic Insects Detect their Prey ? — A variety of 

 opinions have been expressed as to the means by which ichneumon flies 

 and other parasitic insects discover the living objects upon which they 

 seek to deposit their eggs. Some have inferred that this is done by sight, 

 others by smell, or by the operation of some peculiar sense unknown to 

 us. The rapid movements of some of the Hymenopterous parasites 

 which attack caterpillars would rather lead one to suppose that the sense 

 of touch is an agent, if not the sole agent. These flies may be noticed 

 running rapidly up and down leaves and twigs, with vibrating antennae 

 and palpi, sometimes going over very nearly the same ground again and 

 again, which they would hardly do if they chiefly depended upon their 

 eyes ; and were any odour given forth which led them to their victims, 

 these flies would hardly wander about in the manner we see. It is quite 

 possible they may detect even the larvae of Tortriees by the feel of the 

 leaf enclosing these, though the larvae themselves are screened. — J. R. 

 S. C. in Hardwickis Science Gossip. 



Ants and " the Taint of the Hand." — In Nature, July 24, Mr. 

 James D. Hague, writing on the habits of ants, attributes their dislike to 

 the place across which a finger has been drawn to "the taint of the 

 hand." 



Now, Sir, I have frequently drawn a line with a piece of chalk across 

 the track of ants, and observed in them the same symptoms of dislike as 

 Mr. Hague's ants showed to the finger-mark. 



I have also drawn a small circle with chalk round one or more ants, 

 who will seek a spot untouched by the chalk through which to make their 

 escape ; but should there be no such opening, they will presently cross 

 the circle. If, however, this enclosure be made upon a perpendicular 

 wall, &c, they will frequently drop to the ground rather than walk across 

 the line. 



Now, as I have never observed this same dislike — exhibited by drop- 

 ping — of the " taint '"' when ants have been running over my hands, and 

 as the chalk-line has the same effect as the finger-mark, may it not be 

 something else than the " taint of the hand " to which the ants object 

 when their usual track is interfered with ? — G. E. E., Nature. 



