" 163 



Predaceous enemies of the pink boUworm include a bug, Triphleps 

 sp., which, destroys the eggs, and ants, which attack the bollworia 

 whenever they can do so, though they are rarely present in the cotton- 

 fields. Probably the bollworms emerging from stored cotton seed in 

 June and July and again in September and October suffer most 

 from these attacks. The mite, Pediculoides ventricosus, Newp., is a 

 common enemy of the resting stage of P. gossypiella in cotton seed. 

 This mite is viviparous, producing from a few to 270 living young. 

 At a temperature of 90° to 100° F. only six days are required from the 

 time of birth to reproduction of another generation ; from 60° to 70° F., 

 thirteen days are required ; while below 50° F. the mites apparently 

 cannot develop. During January and February in Egypt the life- 

 cycle occupies about 6 weeks. As many as 160 mites have been 

 observed on a smgle larva of P. gossypiella. Bollworms killed by the 

 mites frequently exhibit numbers of dark brown or black spots where 

 the mites have fed. It is doubtful whether this mite can become of 

 much importance as a parasite of P. gossypiella [see this Review, 

 Ser. A, ii, p. 508], as it is incapable of reaching the boUworm when 

 enclosed in a cotton boll, and also because the temperature during 

 the Egyptian winter is not high enough for its development. A 

 Rhizoglyphid mite has also been observed on larvae of P. gossypiella, 

 but it is doubtful whether any serious harm results. A number of 

 spiders and certain birds, as well as toads and frogs, probably exercise 

 some measure of control over the numbers of P. gossypiella. 



A true parasite of the pink bollworm is Pimpla roborator, the female 

 of which oviposits through the lock of dead cotton into the cocoon 

 of the bollworm, and stings the latter into insensibility preparatory to 

 depositing a single egg on the outside of the cocoon. At from 65° to 

 70° F. the incubation period is four days and the larva begins to feed 

 upon its host immediately after hatchmg. After about 9 days, 

 during which two moults occur, the larva is mature, and pupates 

 probably within the cocoon of its host, the adult emerging twelve 

 days later. A table records the life-cycle of a number of individuals 

 bred in the laboratory showing a duration of from 30 to 45 days. 

 P. roborator is apparently parthenogenetic. Its numbers are checked 

 by the fact that many individuals may oviposit in the same host, 

 and also by the fact that eggs may be deposited and development 

 occur in a larva of its own species. This self-parasitism is apparently 

 responsible for the death of many larvae found in the cocoons of 

 pink bollworms. It is pointed out that the destruction of all bolls 

 in the autumn that are infested with P. gossypiellci causes the 

 destruction of large numbers of Pimpla roborator, which becomes 

 really numerous about the latter part of November. 



Two undetermined Pteromalids are parasitic upon the pink boll- 

 worm. The larger is apparently a member of the genus Pteroinalus ; 

 the smaller has the same habit of parasitism as P. roborator. 



The Braconid, Chelonella sulcata, Nees, is believed to live as a 

 larva within the body of the pink bollworm until the latter transforms 

 into the pupal stage; it then completes its growth by feeding upon 

 the pupa. The parasite pupates within the empty pupa of the 

 host. As the ovipositor of C. sulcata is quite short it can probably 

 only attack the bollworms after the bolls have ripened and split open. 

 This parasite is, however, well adapted to the seasonal habits of its host. 



