126 U.S. NATIONAL MUSEUM BULLETIN 266 



sometimes the fruit, of the plants. Typical pale-yellow circular areas 

 arise around each feeding puncture, and the prickly pear joints present 

 a spotted appearance. Where the attack is concentrated, the joints 

 become wholly yellow and sickly. Younger segments may wither and 

 fall off from the injuries, and whole plants may show the unhealthy 

 yellow condition. The growth of the plant is definitely impeded 

 because of the destruction the bugs cause among the young growth 

 and flower buds as they sprout from the joints. In fact, in preventing 

 growth and fruiting, Chelinidea exercises a greater degree of control 

 than in destroying joints and plants. It has frequently been observed 

 that Gloeosporium lunatum and other fungi are prone to attack joints 

 that have been injured by the bugs, and that the fungus lesions de- 

 velop around the feeding punctures. 



The adults, although capable of strong flight, are sluggish insects 

 and rarely take wing. When disturbed they either move rather quickly 

 to the protected side of the joints or drop to the ground. Flight usually 

 occurs under certain climatic influences of high temperature and 

 humidity. In Australia C. tabulate has been known on several occasions 

 to swarm in large numbers and fly in one direction for at least several 

 miles. This phenomenon has been recorded once for C. vittiger. 



The eggs are deposited in a row on the underside of the prickly 

 pear spines, but although this is the usual practice, it is not invariable. 

 Opuntia inermis in Australia produces mainly fine spicules or spine 

 hairs from the areoles and very few long spines. Hence, C. tahulata 

 either lays eggs in clusters on the flat surface of the joints or on any 

 adjacent object i.e., on grass stems and twigs, on or under the bark 

 of tree trunks, and on the foliage of trees and shrubs; quite often its 

 eggs have been found attached to eggsticks of Cactoblastls cactorum. 



Nothing is known of the life history of C. hunteri, but both in the 

 United States and in Australia C. tahulata, C. canyona, and C. vittiger 

 pass through two generations annually. In his review of the genus 

 Chelinidea, J .C. Hamlin (1924, p. 198) suggests that in Texas, C. vittiger 

 has four or five generations, C. tahulata three to five generations, and 

 C. canyona three generations each year. This confusion with regard to 

 seasonal history has arisen because of the frequent occurrence of adults, 

 all stages of larvae, and eggs in any given locality at almost any period 

 during the summer. The explanation of the admixture of various stages 

 lies in several factors; the adults are long lived; the egg-laying period 

 in each generation is extended over 2 to 3 months; and the rate of 

 development of the larvae varies considerably, particularly in the 

 autumn months. The bugs overwinter in the adult stage, but large 

 larvae may be found during the greater portion of winter. During the 

 colder months, the adults shelter among debris, often in congregations. 



