CACTUS-FEEDING INSECTS AND MITES 149 



puntia, the tree pear 0. quimilo, the shrub pears of the 0. monacantha 

 type, and the narrow-jointed pear of the 0. aurantiaca relationship. 



0. quimilo is infested almost wherever it occurs in Santiago del Estero 

 and in the adjoining provinces in the north and west. The shrub pears 

 are greatly favored host plants and include 0. monacantha on the coastal 

 strip near Rio de Janeiro, Brazil, and 0. bonaerensis and several undeter- 

 mined species of the same type in the Provinces of Entre Rios, Cor- 

 rientes, Santa Fe, Santiago del Estero, Tucuman, Salta, and the Chaco 

 in Argentina. In Santiago del Estero, Cordoba, Tucuman, Catamarca, 

 and Salta the common low-growing, narrow-jointed forms 0. utkilio 

 and 0. discolor are regularly infested; a related form 0. anacantha has 

 been found to be attacked in the Chaco; the narrow-jointed but 

 upright-growing 0. salmiana is infested in Santiago del Estero and 

 neighboring regions. A food plant of a different type is an undeter- 

 mined Opuntia related to 0. sulphurea in the Province of Entre Rios. 

 0. sulphureay the common host of the other Argentine cochineal, is 

 seldom attacked by D. ceylonicus in midwestern Argentina. 



In Entre Rios this cochineal is prevalent on 0. monacantha types and 

 on an undetermined species close to 0. sulphur ea^ but has not been 

 found on 0. aurantiaca, even where the three species were growing in 

 the same field. However, no difficulty was experienced in breeding 

 stocks on 0. aurantiaca from material transferred from the related 

 0. utkilio and 0. discolor. 



D. ceylonicus reaches its greatest profusion in March to May, the 

 autumn months. It is subjected to very severe depredations by natural 

 enemies which appear to bring it under control during the late winter 

 and spring. Its increase becomes marked in January and continues 

 until April or May. Observations in the years 1932-34 reported very 

 sparse cultures in August and September and heavy infestations in 

 April and May. 



0. quimilo is often severely attacked, and the younger plants are 

 seriously injured. Prickly pears of the 0. monacantha type, such as 0. 

 bonaerensis and its allies, are frequently covered with cultures; in 

 March 1925 it was reported that between Rosario and Santa Fe the 

 scattered areas of 0. bonaerensis were heavily infested, while at Tostado, 

 Province of Santa Fe, large plants of this species viewed from a distance 

 appeared to be covered with snow. In the Province of Santiago del 

 Estero this insect causes considerable damage to 0. utkilio. 



Dactylopius newsteadi Cockerell 



L. F. Hitchcock of the Board's staff made this determination of coch- 

 ineal infesting 0. imbricata from Carlsbad, New Mexico. In the United 

 States and the northern States of Mexico various Cylindropuntias 



