THE CANADIAN ENTOMOLOGIST. 27 
EDITORIAL SUMMARY. 
How po 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 Tortrices by the feel of the 
leaf enclosing these, though the larvae themselves are screened.— 7. A. 
S. C. in Hardwicke's Science Gossip. 
ANTS AND ‘THE TAINT OF THE Hanp.”—In JVature, 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. Æ, Æ., Nature. 
