THE CANADIAN ENTOMOLOGIST. 41 



previously recorded (though known) in North America. He has called 

 it C. dineutis, and as Mr. Howard, in a recent paper on the biology of the 

 Chalcididae*, has remarked that Hymenopterous parasites of aquatic 

 insects are excessively rare, I have thought it worth while to give a rather 

 detailed account of the circumstances connected with breeding them. 



Two unbroken cells of Gyrimis each contained, besides the remains 

 of the pupa, one specimen of a little Ichneumonid belonging to the 

 sub-family Tryphoninae, which Mr. Ashmead has described as Gausocen- 

 trus gyrini. One of these was quite fresh and bright, the other had been 

 dead long enough to break in handling. I think it extremely unlikely 

 that the Gausocentrus will prove to be a hyper-parasite, but of course this 

 can only be settled with certainty by further observations on the habits of 

 the larva. 



A specimen of the pupa of Tropistenms glaber was given alive to a 

 large Carabid larva for food, but not attacked because the larva had just 

 fed up. Two or three days later it was seen that the pupa was dead and 

 the body infested by maggots, which aftewards produced a species of 

 Fhora, a Dipterous insect which Dr. VVilliston (who kindly furnished the 

 generic determination) writes me is known to enter pupae either living or 

 dead. I have no means of ascertaining when or how the eggs were 

 deposited on the pupa, or whether it was attacked in this way before or 

 after death. 



Besides the two Gyrinidae already mentioned, I found under a stone, 

 close to the margin of the river, another larva somewhat resembling them, 

 with long abdominal filaments, only one of which was terminal. Not 

 being able to see the mouth parts on account of the activity of the living 

 specimens, I was unfortunately led to speak of it as probably a Gyrinid 

 larva in the paper referred to, chiefly becauss of the fact that Packard and 

 Westwood both figure larvos of this family with large heads. The creature 

 lived in a tin box of earth for five weeks, then moulted and died almost 

 immediately afterward. An examination of the mouth shows it to be a 

 Sialid larva, corresponding closely to Westwood's figures, f except that 

 only one of the mandibles has two teeth, the other being furnished with 

 but one, and the outer lobe of the maxilla has a process articulated to the 

 inner angle mstead of a simple production. 



* Proc. U. S. National Museum, Vol. XIV. 

 t Modern Class, of Insects, Vol. II., p. 46. 



