1916 ENTOMOLOGICAL SOCIETY. 59 



The President : I wish to make a slight alteration in the programme because 

 of the circumstances. We have with us a gentleman from Arnprior, Mr. Macnamara, 

 who is rapidly becoming an entomologist — in fact I think he is already an ento- 

 mologist. He has been making some very interesting observations on certain 

 insects to which Dr. Fylcs referred, namely, those extraordinary hymenopterous 

 parasites of the genus Thalessa. Mr, "Macnamara, in addition to being an ento- 

 mologist, is also a photographer of considerable skill, and has been able to apply 

 his photographic knowledge to the recording of the oviposition of those extra- 

 ordinary parasites, some of the most extraordinary parasites we have, and, therefore, 

 I think it is rather fitting that, although I took upon myself to ask Mr. Macnamara 

 to read this paper and it is, therefore, not in the programme as the latter had 

 already been prepared, Mr. Macnamara should give us a brief discussion on his 

 observations of which he has some photographs. 



Mr. Macnamara: You have taken me entirely by surprise. Dr. Hewitt, and 

 I do not think I have much of interest to say, but I have a few photographs of 

 one of the ichneumons that the members may care to see. The prints show the 

 male and female Thalessa, or as the genus is now called, " Megarhyssa" airata; 

 and the female alone with her extraordinary ovipositor separated to show the 

 two sheathes and the drill. Other prints, show the tree infested with Tremex 

 which the M. atrata frequented, and magnified views of the ovipositor, foot and 

 other parts are given. Perhaps the most interesting views are those of the insect 

 in the act of ovipositing, with the flexible sheathes curved over her back. 



I first observed these insects ovipositing on a maple tree in a small hardwood 

 grove about the middle of June. They were in considerable numbers, some days 

 twenty to twenty-five, and continued egg-laying until the middle of September 

 Avhen they disappeared. As their victim, the Tremex never seems to attack per- 

 fectly sound wood,' Megarhyssa generally bores into somewhat decayed material, 

 but it is wonderful that she should be able to drive her ovipositor as she does, 

 to a depth of five or six inches into wood that we find hard enough to cut with 

 a chisel or a knife. 



Dr. Fyles spoke of the instinct which enables them to discover the tree 

 tunnelled by the Tremex. Their instinct in this respect is remarkable, but by 

 no means infallible. The Megarhyssa I observed frequently only on one tree 

 in a grove of five or six acres, and frequent and careful search failed to discover 

 them on any other tree in the wood. But in October a large maple nearby, 

 broken off by a gale, was found to be riddled by Tremex and no Megarhyssa 

 had ever discovered them. 



As Dr. Hewitt has taken me entirely by surprise I hope you will excuse the 

 crudeness of my remarks, as I have not had time to prepare anything, but 

 "prol)ably the photographs will prove interesting to some of you. 



The President : I think the pliotographs which are going around will prove 

 my statement that we have with us a photographer-turned entomologist, and those 

 of you who remember Mr. Macnamara's previous contributions to entomology 

 in the shape of his account of the habits and some notes on the biology of those 

 verv small, little-studied creatures. Arhonites, will agree with me that we have 

 a very ardent entomologist in Mr. Macnamara, and I do not think that he will 

 need any further introduction or words to back up his election for membership 

 when his name comes forward, as it will to-morrow. 



Prof. Caesar: This photograph of Mr. Macnamara's, showing ovipositing 

 is extremely good. It is a most wonderful thing to look at this insect ovipositing. 



