22 



PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



summer of 1906 a number of parasites were taken from Waco, Tex., 

 and liberated in a cotton field near Dallas, Tex., and apparently by 

 this means the mortality rate due to parasites was raised in a few 

 weeks about 9 per cent. Later, parasites were introduced from Texas 

 into Louisiana and increased the mortality of the weevil. Work of 

 this character is still being carried on by Mr. Hunter, and elaborate, 

 although as yet unsuccessful, experiments have been made by Web- 

 ster in the transfer of the hymenopterous parasite Lysiphlebus tritici 

 Ashm. (fig. 3) from southern points into Kansas wheat fields for the 

 destruction of the spring grain aphis or so-called " green bug" (Toxop- 

 tera graminum Rond.), definite results being prevented by the occur- 

 rence of the parasite throughout the range of the destructive insect, 

 parasitic, as it is, upon other species of plant lice. 



Prof. S. J. Hunter, of the University of Kansas, however, in the 

 Bulletin of the University (vol. 9, p. 2) states that he was able, in 

 1908, to hasten the destruction of the- Toxoptera in Kansas by the 

 importation of Lysiphlebus from some other point. 



In the last two years 

 some very interesting 

 work has been carried 

 on by the State Horticul- 

 tural Commission of Cal- 

 ifornia in the way of col- 

 lecting Coccinellidse on a 

 large scale in their hiber- 

 nating quarters, boxing 

 them, and sending them 

 to different parts of the 

 State for use against plant lice upon truck crops. The biennial report 

 of the commissioner of horticulture for 1907-8, published in Sacra- 

 mento in 1909, for example, indicates that 50,000 specimens of the 

 ladybird beetles Hippodamia convergens Guer. and Coccinella cali- 

 fornica Mann, had been so collected. This, however, was very small 

 compared to the scale upon which these insects were collected dur- 

 ing the winter of 1909-10. Mr. E. K. Carnes, of the commission, 

 writing to the Bureau of Entomology under date of March 14, 1910, 

 makes the following statement : 



We have quite a sight at the insectary now— over a ton of Hippodamia convergens, 

 boxed in 60,000 lots each, screened cases, and in our own cold storage. We handle 

 them in large cages, run them into a chute, and handle like grain. They are for the 

 melon growers of the Imperial Valley. 



This species collects in large numbers late in summer and early in 

 the autumn at the bases of plants in the mountain valleys and can 

 easily be collected by the sackful. The actual good accomplished by 

 the distribution of these ladybirds among the melon growers has not 



Fig. 3. ^-Lysiphlebus tritici attacking a grain aphis. 

 (From Webster.) 



Enlarged. 



