20 PRINCIPAL CACTUS INSECTS OF UNITED STATES. 



Chelinidea sp. 



A third species of the genus Chelinidea was taken in May at 

 Tuscon, Ariz., on Opuntia arbuscvla, 0. versicolor, and O. fulgida. 

 This species is somewhat smaller than the preceding. Rearing ex- 

 periments were unsuccessful on account of the shipment of the species 

 into a region of different climate. 



The Control of Chelinidea vittigera and Allied Species. 



Two features of the life history of these bugs reveal feasible means 

 of control. These are the clustering of the adults during winter and 

 the gregarious habits of the young. The best control practice to 

 follow is undoubtedly to collect and burn the trash on which the 

 insects are found during the winter. At that time they are almost 

 completely dormant and can be raked into piles along with the 

 debris and burned. The gregarious habit, which is especially well 

 marked in the earlier immature stages, makes it easy to check the 

 development in a different way. The use of the gasoline torch, which 

 is found upon all plantations where the cactus is used for forage, 

 gives an economical and effective method of destroying these stages. 

 Whenever the appearance of the small circular spot and of the white 

 excrement shows that the insects are beginning to injure the plants 

 seriously, the torch can be brought into play to excellent advantage. 



Mimorista flavidissimalis Grote. 1 



The cactus insect Mimorista flavidissimalis Grote may be rec- 

 ognized easily from the following description : 



From one to seven yellowish larvae feeding invariably on upper 

 edge of young joints of Opuntia under a silken web, sometimes pene- 

 trating the interior. (PI. III.) 



After the Chelinidea bugs, this insect is the most important enemy 

 of Opuntia in the United States. Unlike the Chelinideas, however, 

 it is restricted in its range. In Texas it is found from Hallettsville 

 and San Antonio southward. West of San Antonio it is rare, but 

 was taken at Tucson, Ariz., in May by Mr. Pratt. In the area where 

 it is common it is by far the most injurious cactus insect. 



The species was described by Grote in 1877 from specimens re- 

 ceived from Texas. Since then it has not been recorded outside of 

 Texas. It was not until 1905, when the present work was under- 

 taken, that anything was known about the early stages. The first 

 rearings were made at Washington. D. C, from material collected 

 at San Antonio, Tex., by Mr. David Griffiths. 



1 Order Lepidoptera, family Pyralidae. 



