PINK BOLLWORM OF COTTON IjST MEXICO. 21 



season till December and make a complete life cycle every 31 days, 

 there are six generations, but if the moths do not emerge from the 

 resting larvae until the fall and the first generation goes into the rest- 

 ing stage again, the whole year may be passed jn only one generation. 



FEEDING HABITS OF LARV^. 



LARXM FEEDING ON LEAVES AND STEMS. 



The feeding of the pink bollworm on the leaves of cotton is of no 

 economic importance. It is a forced condition rather than a voluntary 

 one. If the eggs have been deposited a long way from the squares 

 or bolls, the larvae may feed slightly on the leaves while searching for 

 suitable food. In such cases slight abrasions on the surface of the 

 leaf or minute pinholes through the leaf occur. The larvae feeding 

 in this manner appear either to die for lack of sufficient nourishment 

 or to be destroyed by other insects. No larvae older than those of 

 the second instar were ever observed feeding on leaves and only 

 two or three cases of the second instar. No indications of entrance 

 into the bolls by larvae of the second or later stages were ever 

 observed under field conditions, except where the larvae had been 

 feeding in blossoms and had worked downward into the newly set 

 bolls. Willcocks (7) records larvae feeding in the stems of the 

 plants just above the surface of the ground in Egypt, but this class 

 of injury was never seen in the Laguna. 



LARVAE FEEDING IN SQUARES AND FLOWERS. 



The young larvae enter the squares by cutting directly through the 

 undeveloped flower petals and feed on the pollen and fleshy parts 

 of the embryonic flower, usually reaching the third or fourth instar 

 by the time the flower opens. These infested flowers do not open 

 normally, but have a peculiar rosette appearance which is well shown 

 in Plate III, A. The tips of the corolla in infested flowers are 

 webbed together by the larvae with fine silken threads which prevent 

 their opening wide and exposing the larvae to the attacks of other 

 insects and the heat of the sun. 



These infested flowers are easily distinguishable from normal 

 flowers in walking through fields of upland or short-staple varieties. 

 Even though the percentage of infested flowers was about the same 

 in Egyptian or long-staple cotton the pronounced rosette effect was 

 never seen. The corolla is longer and larger in Egyptian varieties 

 and the threads spun by the larva probably are not sufficiently 

 strong to prevent its opening. When infested flowers are examined 

 the larva is usually found beneath a fine silky web, covered with 

 frass and pollen grains, and feeding upon the anthers. If full-fed when 

 the flower opens it may leave it the first day and drop to the ground 

 for pupation. This is especially apt to occur if the larva is dis- 



