46 PLANT-BUGS INJUKIOUS TO COTTON BOLLS. 



Table XX. — Summary of laboratory feeding records on the conchuela, Lot A. 



Place. 



Time. 



Per cent feed- 

 ing in daylight. 



Per cent feed- 

 ing at night. 



Per cent feed- 

 ing, day and 

 night. 





July 20-22,1905 

 Sept. 4-8, 1905 



59.4 

 27.2 



89.8 

 62.5 



74 6 



Dallas Tex 



44 8 







A comparison of Tables XVII and XVIII shows a close corre- 

 spondence between the laboratory and field observations on the 

 amount of time the adults spend in feeding during daylight. The 

 fact that in the field the conchuela feeds almost constantly after sun- 

 set has already been recorded.^ We may safely assume that the 

 adults feed for fully as large a percentage of the nighttime in the 

 field as in the laboratory. Considering, therefore, that 90 per cent 

 of the night (Table XVIII), and 66 per cent of the day, is spent in 

 feeding, the percentage of the calendar day spent in feeding at the 

 times and places of these observations was approximatel}/" 78. 



Table XX shows a difference between the same lot of insects 

 which is probably attributable to the difference in age of the speci- 

 mens. Difference in temperature could have had no appreciable 

 effect as it was slight, the average daily mean at Tlahualilo on the 

 days of the observations being 76° F. and at Dallas 79° F. 



Method of attack. — For locating the position for piercing the carpel 

 of a cotton boll the conchuela makes use of its antennae and tip of 

 the rostrum. As in other Heteroptera, the rostrum is used only as 

 a guide for the threadlike setae and is never forced into the object 

 upon which the insect may feed. As the setae sink into the boll the 

 rostrum bends at the joint between the first and second segments, 

 being directed backward. The setse at the same time are freed from 

 the rostral groove of the basal two segments, and as these two seg- 

 ments fold together, this allows a greater depth of penetration. 

 Next, the apical or fourth segment is bent or folded back leaving the 

 setae in the rostral groove only at the angle between the third and 

 fourth segments. In this position the rostrum forms a letter "Z," 

 the upper angle representing the joint between the second and third 

 and the lower angle the joint between the third and fourth segments. 

 Feeding may be continued with the rostrum in this position or the 

 rostrum may be freed entirely from the setae and directed straight 

 back along the middle of the venter in the usual position it occupies 

 when the insect is resting or crawling. The insect may therefore use 

 practically the entire length of the setae to penetrate through the 

 carpel and the developing lint to the cotton seed. This length is 

 about one-fourth of an inch. When feeding, the bug alternately 



aBuL 54, Bur. Ent., U. S. Dept. Agr., p. 26, 1905. 



