194 The American Naturalist. [February, 
look, and not until the Aphis abandons them in the autumn to retum 
to the apple, do they show any amount of vigor.” 
This leaves the summer period still unaccounted for, but in the dis- 
cussion which followed Mr. Webster’s paper, Dr. C. V. Riley stated 
that he had “ for a number of years known that this species had a sum- 
mer existence on various grasses. ”* 
Nematodes in Cecidomyia.—<At a recent meeting of the Societ 
Entomologique de France, M. A. Girard called attention to the obser- 
vation of Kieffer’ as to the existence of Nematode parasites in a female 
cecidomyiid (Asynapta citrina Kieff.). A fly of this species stupified 
by nitro-benzine emitted from the oviduct a compact mass of Anguil- 
lulas which placed in water moved about rapidly. Kieffer thought 
that the alimentary canal also contained these Nematodes, but Girard 
believes it to be a case where only the abdomen, especially the region of 
the ovaries is inhabited by the parasite. He reports a similar obser- 
vation of his own, in which an undetermined cecidomyiid was the host. 
The body cavity was nearly filled with a Nematode of the genus As 
conema and its embryos. The ovaries of the fly were atrophied by 
parasitic castration. The eggs of the Nematode developed in the body 
of the fly, and the latter laid the little Anguillulas in humid situations 
where they could develop. 
Flights of Dragon-Flies.—-In. Mr. W. H. Hudson’s recently pub- 
lished Naturalist in La Plata there is an extremely interesting chapter 
on Dragon-fly Storms. In the Pampas and Patagonia, the larger spe 
cies of these insects—especially Æschna bonariensis Raml., a p 
form—frequently occur in enormous flocks which appear 
as these insects are not seen in the country at other times, and frequ 
appear in seasons of prolonged drouth, when all the marshes and water 
courses for many hundreds of miles are dry, they must of course tra 
verse immense distances, flying before the wind at a speed of seventy oF 
eighty miles an hour. * * * As a rule they make their appearan 
from five to fifteen minutes before the wind strikes; and when they 4 
in great numbers, the air to a height of ten or twelve feet above 
surface of the ground, is all at once seen to be full of them, wn 
past with extraordinary velocity in a northeasterly direction. r ep 
All journey in a northeasterly direction ; and of the countless m1 
*tInsect Life, VI, 152. 
‘Berlin Ent. Zeitsch., XXXVI, 1891, p. 266. 
