14 



less c-loiided. The principal food of the moths in cotton fields is the 

 nectar secreted ])y the glands at the base of the bracts surrounding 

 tte s(|uaros and flowers. Many moths are doubtless attracted to cotton 

 fields on account of the aliundaiice of nectar, and we have the unusual 



condition in Nature of a 

 plant attracting its own 

 worst eneni}". 



It is difficult to deter- 

 mine the number of eggs 

 deposited by a moth un- 

 der normal conditions in 

 the field. In the labora- 

 tory at Victoria moths 

 kept in confinement and 

 fed on sugar water aver- 

 aged about 1,200 eggs 

 each, with a range of from 

 900 to about 2,200. This 

 is a considerably larger 

 number than has hereto- 

 fore been accredited to 

 this species. Estimating 

 that onlv 10 per cent of 

 the 1,200 eggs hatch, and 

 that of this number one- 

 half will produce females 

 capable of laying eggs, 

 the progeny of one moth appearing in spring b}- the fourth, or 

 August, generation would be 25,920 bollworiiis, and by September, or 

 the fifth generation, the number would be 15.5,520. It is thus readily 

 understood how, under favorable conditions, the bollworm may become 

 so numerous and destructive. 



Fi 



-Opened boll to show bollworm at work within — natu- 

 ral size (original). 



SOME FACTORS WHICH TEND TO KEEP BOLLWORMS REDUCED. 



Owing to their habits of feeding more or less protected from the 

 attack of parasitic and predaceous insects, bollworms enjoy consider- 

 able freedom from important natural checks. The eggs are freely 

 parasitized by a small hymenopterous insect, during certain periods 

 from 50 to T5 per cent being thus destroyed. The larvte are preyed 

 upon by several species of wasps, and also b}^ ants, which do consid- 

 erable good in this way. They are parasitized by certain Tachina 

 files, and succumb in considerable lunnbers at times to a bacterial dis- 

 ease. During the spring and fall, when the variation in temperature 

 is greater, many bollworms die of this disease before entering the soil 

 to pupate, or shortly afterwards. 



191 



