1909] Toxoptera graminum and its Parasites 77 



develop countless millions of winged viviparous $ 9 , and these- 

 will gradually become diffused northward as the season advances 

 and weather conditions favor them. Indeed the experience of 

 Rondani and Bertoloni, in Italy, found an equal in the southwest 

 in 1907 where Mr. C. N. Ainslie observed the winged ? 9 in such 

 swarms as to interfere not only with a Sunday game of baseball,, 

 but also with the conducting of a funeral. North of about Lat. 

 38° the season is so far advanced that wheat becomes too large 

 and tough to offer the requisite food supply, but spring oats here 

 prove a convenient and attractive supplement and it is usually 

 this crop that suffers most to the northward, provided, of course, 

 the weather conditions are not favorable to the development of 

 natural enemies. 



NATURAL ENEMIES. 



There are a number of these, especially among the Coccinelli- 

 dffi, several species of which feed, both in the larval and adult 

 stages, on Toxoptera. Syrphus flies and Chrysopa also destroy 

 them. Apheliniis nigritits Howard, recently described, is a min- 

 ute parasite that has been reared from this insect in South Caro- 

 lina by Geo. G. Ainslie, and in New Mexico by Chas. N. Ainslie, 

 both assistants in the Bureau of Entomology. Quails are very 

 fond of them and Miss Margaret Morse of Clarke University has 

 been kind enough to make some experiments for us in feeding these 

 birds. Miss Morse estimates that about 5,000 individual Toxop- 

 tera were eaten by a single quail in one day, preference being 

 show^n for those that were unparasitized. The Song Sparrow, 

 Melospiza melodia, also devours great numbers of them in the 

 grain fields. 



DEVELOPMENT AND INFLUENCE OF LYSIPHLEBUS TRITICI. 



As a matter of fact, however, all of the natural enemies pre- 

 viously mentioned are of small moment as compared to the influ- 

 ence of the one minute parasitic species Lysiphlebiis tritici (figs. 

 5, 6.). It is this species, or w^hat we are at present terming as 

 such, that normally holds Toxoptera in check in this country, and 

 so long as its development and activity are not obstructed by 

 meteorological conditions, it will probably continue to do so. 

 Indeed so important is this insect and so powerful is its influence 

 that only a short space of from ten days to two weeks time is 



