MEXICAN CONCHUELA IN WESTERN TEXAS IN 1905. 9 



last of JiiW, after which the number diminishes rapidly. The bugs 

 are strong fliers, which accounts for their sudden appearance on a 

 given crop, and in some cases for their sudden disappearence from it. 

 On Jul}' 20-22 no eggs or young could be found on the infested 

 peach trees, nor could any of these stages be found on August 11 and 

 12 after the adults had entirely disappeared from the trees. If any 

 eggs were deposited by the bugs when the latter were attacking the 

 peaches the resulting nymphs Avere probably carried to the ground 

 with the falling of the fruit, for the interval between the examina- 

 tions was not sufficiently long for them to have reached the winged 

 or adult stage. The only breeding places of consequence found at 

 Barstow were in the alfalfa fields. Here eggs and nymphs were found 

 in large numbers on August 11 and 12. A "month later the insects 

 had been reduced by at least one-half, and their scarcity was noticeable 

 everywhere except in small areas in some fields of alfalfa and along 

 the borders near fences and ditches where the cuttings had not been 

 made at regular intervals. Of 32 adult pentatomids collected in the 

 alfalfa fields September 12, 2G were P. ligata and 6 P. sayi. At the 

 next examination, on October 13, it was evident that the insects were 

 still decreasing in numbers, but the n3nuphs in the last two stages 

 were proportionally more abundant than before. In the lot of 16 

 adults and 49 nymphs collected at that time, P. sayi was not repre- 

 .sented. The last examination, made on Xovember 14, showed that 

 the conchuelas had almost entirel}^ disappeared; a half hour's search 

 where, at the time of previous examinations, they had been found 

 most abundant, resulted in the capture of only 6 adults, no nymphs 

 being seen. 



NATURAL ENEMIES. 



EGG TARASITES. 



IVIinute Qgg parasites belonging to the family ProctotrypidcC are 

 generally known among entomologists to play an important role in 

 checking the nudtiplication of many insects, so that anything which 

 affects the numbers of these parasites frequently results in a corre- 

 sponding benefit or injury to the crops attacked by the host insects. 

 If these parasites of the Q^g^ of pentatomids were eliminated, many 

 of the pentatomids would undoubtedly be ranked among our most 

 impoi-tant insect j^ests. The importance of these parasites in check- 

 ing the multiplication of the conchuela at Barstow in 100;") can be 

 best emphasized by summarizing the results obtained by rearing 

 parasites from eggs collected at that place. 



