MEXICAN CONCHUELA IN WESTERN TEXAS IN lHOo. V) 



last of Jiih', after which the iiuiubci' (liniini.shcs I'iipidly. The bug's 

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

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

 On July 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 w^ere probably carried to the ground 

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

 tions w^as not sufficiently long for them to have reached the winged 

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

 BarstoAv 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 interA'als. Of 32 adult pentatomids collected in the 

 alfalfa fields September 12, 26 were P. ligata and G /-*. sayi At the 

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

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

 were proportionally more abundant than before. In the lot of 10 

 adults and 4!) nymphs collected at that time, P. sayi was not repre- 

 ;jented. The last examination, made on November 14, showed that 

 the conchuelas had almost entirely disappeared; a half hour's search 

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

 most abundant, resulted in the ('a[)ture of only (> adults, no nymphs 

 being seen. 



NATURAL ENEMIES. 



K(;(; I'AKAsrrKs. 



Minute egg parasites belonging to the family l*roctotrypiche are 

 generally known among entomologists to play an important role in 

 checking the nndtiplication of many insects, so that anything which 

 ati'ects 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 eggs of })entatomi(ls were eliminated, many 

 of the pentatomids Avould undoubtedly be ranked among our most 

 important insect pests. The importance of these parasites in check- 

 ing the nniltij^lication of the conchuela at Barstow iu 100.") can be 

 best emphasized by summarizing the results obtained by rearing 

 parasites from eggs collected at that place. 



