64 PLANT-BUGS INJURIOUS TO COTTON BOLLS. 



the total of over 1,200 eggs collected in the field. Of 156 eggs, rep- 

 resenting the ^ve batches collected in the field from which no par- 

 asites were reared, only 1 egg failed to hatch. It has been stated that 

 in the laboratory all but about 7 per cent of fertile eggs hatched. 

 Even allowing for eggs destroyed by predaceous insects and the small 

 percentage which normally fails to hatch, it is evident that the total 

 percentage of conchuela eggs destroyed by Proctotrypid parasites is 

 from 15 to 25 per cent above the percentage shown in the table from 

 which parasites actually matured and emerged. 



Parasites Attacking Adults and Nymphs. 



The only parasite of the conchuela attacking the adults and nymphs 

 which has come under the writer's observation, is the Tachinid fly 

 Gymnosoma fuliginosa Desv. (PI. Ill, figs. 9, 10). The female of this 

 species deposits her eggs on the adults and nymphs in the fifth 

 nymphal instar, usually near the margin, on the anterior half of 

 the body (PI. Ill, fig. 9). So far as observed, the percentage of these 

 bugs which are parasitized by this fly is not large. Observations at 

 Tlahualilo, Mexico, and at Barstow, Tex., in 1905, indicated that it 

 was never more than 5 per cent. Under favorable conditions these 

 Tachinid flies might attain a high degree of usefulness, but it is prob- 

 able that they seldom exert much influence toward the reduction of 

 the numbers of the conchuela and other Pentatomid pests. 



Predatory Enemies, 

 invertebrates. 



No one of the invertebrate enemies of the conchuela or of other 

 Pentatomids has, in the writer's experience, shown itself to be of any 

 great importance. Taken together, however, they form a group 

 entitled to consideration. 



Attacking eggs. — Nymphs of other species of Pentatomids as weU 

 as of the conchuela itself may destroy eggs in the field. The only 

 species observed actually engaged in feeding on unhatched eggs of the 

 conchuela is Thyanta custator Fab., the specimens being in the fifth 

 instar. The well-known predaceous Anthocorid, TripJileps insidiosus 

 Say, doubtless is as fond of the eggs of Pentatomids as of the eggs 

 of other insects. The same may be said of the larvae of various species 

 of Chrysopa, although specific observations have not been recorded 

 in either case. It is not uncommon to find the remains of eggs of 

 the conchuela which have the almost unmistakable appearance of 

 having been destroyed by predatory insects provided with mandibles. 

 Entire batches consisting of as many as 14 eggs have been found in 

 this condition with the circumstances indicating that a single insect 

 had been responsible for the destruction of each batch. It is probable 



