60 



ENTOMOLOGICAL SOCIETY. 



strong and provided with curved hooks — an admirable contrivance to enable the parasite 

 to travel through the maze of feathers while the troubled host travelled through the 

 mazes of the northern forest. 



Through the kindness of my friend, Mr. Dearness, I am 

 enabled to present herewith a drawing made by him under the 

 microscope, which shows the structure of the fly's foot. (Fig. 33.) 



The most interesting feature of the particular specimen 

 described above lay in the fact that when found its condition gave 

 me hopes that I might receive some light on its method of repro- 

 duction. Its abdomen was much larger in proportion than that 

 of its congener found on the hawk. 



Having placed the fly, living and uninjured, in a small phial, 

 I watched and awaited developments. Within twenty hours I 

 found the fly dead at the bottom, and a single large pupa (Fig 34) 

 sticking to the side of the bottle. As it appears 

 incredible that the young could have subsisted by 

 itself in such a place, it seems reasonable to conclude 

 that the egg and larval stages were passed within 

 tie body of the parent, thus accounting for two 

 important phases in the course of its life. The pupa 

 measured 2^x2 millimeters, blackish brown, smooth 

 and shining, flattish, oval, suggesting in form and 

 outward structure some minute trilobite. 



Fig. 33. 



Foot of Parasite of 



White-throated Sparrow. 



Fig. 34. 



Form of the 



shining black 



pupa. 



Mr. J. Dearness submitted the specimens of the two parasitic insects, and the 

 curious larva, adding the following notes : 



With the specimens submitted herewith, Mr. Elliott has afforded some of us our 

 first opportunity of examining a pupiparous insect. He shrewdly suspected the curious 

 fact in the life history of the insect under notice that the earlier metamorphoses take 

 place in the abdomen of the parent, and that the young insect emerges therefrom in the 

 pupal stage. The adhesiveness of the pupa, a3 shown by its sticking to the side of 

 glass bottle, may be an important agent in keeping the pupa among the feathers during 

 the brief time between its expulsion and its exit as an imago. 



The only book T had at hand at the time of making these notes which relates 

 anything of the Pupiparse was Van der Hoeven's. Speaking of the Pferde-laus (Hippo- 

 bosca equina L.) he says : " If we were told that a bird laid an egg that produced a 

 young one at once as large as the mother we should think the account fabulous and 

 ridiculous ; the fabulous part would not be diminished were th,e bird ever so small, or 

 even a winged insect. Of this insect — the Pferde-laus — the story is actually true." 



The smaller of the two parasites was the one that deposited the pupa in the bottle ; 

 it is in the genus Ornithomyia, Latr., and is characterised by having distinct eyes, 

 ocelli usually three, wings distinct, claws of tarsi tri-dentate. Hippobosca has no ocelli, 

 and the tarsi are bi- dentate. 



The author above quoted says of the family to which these insects belong that they 

 lay no eggs, but are viviparous. That which seems to be an egg laid by these insects, 

 and which is sometimes as big as the abdomen of the mother, ought to be regarded as a 

 pupa. From it the perfect insect (imago) comes to view after an interval of time 

 dependent upon the temperature to which the pupa is exposed. 



