42 PLANT-BUGS INJURIOUS TO COTTON BOLLS. 



part the nymphs are dependent on the juices of plants for food 

 although eggs of their own and other species of insects are fed upon 

 with relish wherever accident places them in their way. Except for this 

 habit of feeding on insect eggs, the writer has never observed nymphs 

 of the conchuela to attack living insects. In one instance, however, 

 a nymph in the fifth instar exhibited a decided preference for ani- 

 mal food over vegetable. This nymph was in a cage in the labora- 

 tory with specimens of other species of Pentatomids, including a 

 nymph in the fifth instar of Podisus lineatus H. Schf. This last- 

 mentioned specimen died, but was not removed from the cage, and 24 

 hours later the nymph of the conchuela was observed feeding on 

 the dead insect. As there was a fresh cotton boll in the cage, feeding 

 on the dead inse3t was clearly a matter of preference. 



The habits of nymphs on the cotton plant are much like those of 

 the adults, except that the nymphs are less conspicuous, frequently 

 being entirely hidden by the bracts of the bolls. They have a well- 

 marked gregarious tendency, especially in the first three stages, dur- 

 ing w^hich all the surviving nymphs of a brood are usually found on 

 the same boll. In a field at Tlahualilo, nymphs of the fifth instar 

 occurred in unusual abundance in a field of cotton averaging 5 or 6 

 bolls over 1 inch in diameter per plant. The nymphs reached the 

 plants by crawling, and at the time of examination while less than 

 one-fourth of the total number of bolls were infested, as a rule, each 

 infested boll had several nymphs clustered upon it. As many as 

 17 fifth-instar nymphs were counted on a single boll, while frequently 

 from 5 to 15 nymphs were found on a single boll, with the plant 

 otherwise free from the pest. 



DISTANCE CAPABLE OF TRAVELING FOR FOOD. 



The distance which nymphs of the conchuela are capable of travel- 

 ing for food proved to be a matter of considerable importance at 

 Tlahualilo in 1905, owing to an invasion by nymphs of vineyards, 

 gardens, and cotton fields adjoining an alfalfa field where the insects 

 were breeding in enormous numbers. The cutting of the alfalfa 

 removed the food supply of the insects, thereby causing a migration 

 in search of food." The adults distributed themselves by flight, 

 but the migration of the nymphs was limited by their capabilities 

 for crawling. Few of the nymphs in the first 3 instars got beyond 



a Migrations of this kind have not been previously unknown among the Penta- 

 tomidae. Prof. D. A. Saunders in reporting an unusual outbreak of Uhler's green 

 plant-bug (Pentatoma uhleri?) in South Dakota says regarding this point: "By the 

 middle of June the bugs, being now about half-grown and their wings beginning to 

 appear, began to migrate in great droves 'on foot' toward the cultivated fields. Mr. 

 Senn estimates that they would make about one-half mile in a little less than a day 

 across cultivated fields * * *." (Bui. 57, S. Dak. Exp. Sta., p. 39, Feb., 1898.) 



