312 THE CANADIAN ENTOMOLOGIST. 



but both the primaries and secondaries are crossed by very broad, white 

 bands, as in L. arthemis. It is, however, larger than any specimens of 

 Arthemis I have ever seen, and exceeds the majority of L. Ursula in size. 

 It has the white spots in the cell of the primaries which appear in some 

 female specimens of L. Weidemeyeri. It is altogether a queer beast 

 combining the characteristics of three of cur species. No doubt they 

 all sprang from a common ancestry, and this specimen reveals the force 

 of atavism. 



EXOCHILUM MUNDUM, SAY, ATTACKING THE FALL 



WEB-WORM. 



BY A. H. KIRKLAND, ASSISTANT IN THE AMHERST, MASS., INSECTARY. 



One hot afternoon in the early part of August, 1S93, while out collect- 

 ing, I found a large web of the Fall Web- Worm ( Hyphantriaciinea, Drury), 

 on a young apple tree. Reaching up to cut off the twigs to which the 

 web was attached, my attention was attracted by an unusual disturbance 

 among the inmates of the web. Closer inspection revealed the fact that 

 a medium-sized Ichneumon fly had intruded within the family circle, and 

 was proving herself a most unwelcome visitor. Tearing into the web with 

 her feet she would force her way along until she arrived under the 

 skeletonized leaves upon which the larvae were resting and through which 

 they were plainly visible. W 7 hen her presence was noticed by the larvae 

 lying on a large leaf nearest the intruder, they raised their heads and 

 swung them rapidly from side to side, and at the same time each one 

 emitted a drop of greenish fluid from its mouth. Meanwhile the Ichneu- 

 monid had crept up under the leaf, and bending the posterior segments of 

 her abdomen until the partly exserted ovipositor extended forward between 

 the feet and beyond the head, she poised herself for a moment as if to 

 take aim, then with lightning rapidity she darted her abdomen and ovi- 

 positor still farther forward and struck through the leaf into the body of a 

 larva, which at once commenced to writhe and twist as if in great pain. I 

 watched this operation continue for about half an hour and did not observe 

 the Ichneumonid sting any larva more than three or four times, usually 

 but once. 



Upon attempting its capture it broke out of the web and flew off. 

 Soon, however, it returned, and after circling about for a short time as if 

 to select a favorable place for renewing operations, it alighted and again 

 forced an entrance into the web. This time my efforts were successful, 

 and my capture, as kindly determined by Prof. Fernald, proved to be 

 Exochilum mundum, Say. The larvae that had been stung were brought 

 to the Insectary for the purpose of obtaining more specimens of this 

 interesting Ichneumonid. 



