48 PLANT-BUGS INJURIOUS TO COTTON BOLLS. 



cotton plants. Field observations showed that whatever the nature 

 of the attraction which is the basis of the occurrence, it is operative 

 between the different species of Pentatomids as well as between 

 individuals of the same species. 



As a result of this gregarious tendency it was found that of 467 

 cotton plants exaniined on July 15, 1905, in one of the most heavily 

 infested sections of the plantation at Tlahualilo, the infested plants, 

 or those plants upon which there was at least 1 bug, numbered 91 

 and averaged about 2 bugs per plant. There were therefore about 

 five times as many of the insects upon the infested plants as upon 

 the average of the plants examined. A further concentration of 

 these bugs was observed on the individual bolls. Of 100 bolls upon 

 which one or more of the bugs was feeding 52 were found to have 

 from 2 to 5 bugs each and 48 only 1 bug each. In all, there were 

 175 bugs feeding on the 100 bolls. 



In September, 1904, conchuelas in the field showed themselves 

 capable of only short flights, about 25 feet being the maximum dis- 

 tance attained by any one effort observed. In July of the following 

 year observations showed these insects to be strong fliers. Gentle 

 winds have little effect on the flight of the insects, as they seem to fly 

 as often against as with the wind. Many of the insects have been 

 observed to fly as far as the eye could follow. In one instance when 

 lost to view the specimen was about 50 feet above the ground and 

 gradually rising higher; in another case a specimen disappeared 

 from view without rising higher than 15 or 20 feet. 



The numbers of the insects in any given locality are subject to 

 rapid changes owing to their flying propensities, but extensive 

 migrations are always traceable to the need for a fresh food supply. 



SEASONAL HISTORY. 



INCREASE AND DECREASE IN NUMBERS DURING THE SEASON. 



Previous to the season of 1903, as far as can be learned, the con- 

 chuelas attracted no particular attention as cotton pests in the 

 Laguna district of Mexico. For the information here presented 

 concerning the seasonal history of these insects in 1903 and 1904 

 the author is iadebted to Mr. John Conduit, resident manager of the 

 Tlahualilo cotton plantations, who, owing to the immense tract of 

 cotton grown under his supervision, gives particular attention to 

 cotton pests, and in addition to personal examinations in the fields 

 directs the '' bosses" of the various parts of the estate to send in to 

 the office specimens of insects taken on the cotton plants, with 

 information concerning their abundance. The bosses in their turn 

 make examinations and send dozens of laborers into the various 



