60 CIRCULAR 16 8, U. S. DEPARTMENT OF AGRICULTURE 



COTTON INSECTS 



The worst of the cotton pests is the well-known pink bollworm, 

 Pectinophora gossypiella (89, 167), which, according to Okamoto, 

 infests an average of 50 per cent of the bolls each year in Chosen. 

 It also occurs in Japan and in Taiwan, largely in the district about 

 Tainan, and is spreading rapidly. It was presumably introduced 

 into the island from India, and an infestation in some cases of 50 

 per cent has been noted. In Chosen two broods are produced annu- 

 ally, the mature larvae of the second brood hibernating in cocoons 

 in the soil or in rubbish and crevices. This is in marked contrast 

 to the habit of the species as recorded by Gough in Egypt, where 

 the resting stage larvae were always found to be in seed, either 

 ginned or in abandoned bolls in the field. The adults of the first 

 brood appear in the earty part of July and those of the second in 

 the middle of August. The eggs of the first brood are laid upon 

 flower buds and developing bolls or on the stems near by, and the 

 larvae feed within the flower buds and young bolls, which conse- 

 quently fall. Pupation is either in these fallen boils or in the soil. 

 The eggs of the second brood are placed in the crevices between the 

 sections of the boll, near the base, and the larvae penetrate and feed 

 upon the seeds, thus preventing the maturing and opening of the 

 boll. The affected bolls do not drop from the plant. Green hemp is 

 mentioned as a host plant in addition to cotton, but no others have 

 thus far been noted. The control measures recommended are chiefly 

 cultural, and consist of cultivating and harrowing the soil to kill 

 the larvae and pupae, the gathering of fallen buds in late July and 

 early August, and the burning of old plants and rubbish at the end 

 of the season. 



The gelechiid Oecophora inopisema is recorded from Japan (95). 

 The life cycle covers one year, the adults appearing during June. 

 The larvae feed in the seed of the cotton and hibernate in the seed 

 in the mature stage. 



Farias cttpreoviridis (E. chromatarw Wlk.) (95) occurs in Japan 

 and Taiwan and in the latter island has one brood each year. The 

 winter is passed in the pupal stage. The adult moths emerge in 

 late June and July. The eggs are deposited on the cotton squares, 

 and the young larvae bore into the developing boll, feeding upon the 

 seeds and lint. When mature the larva leaves the boll and forms its 

 cocoon upon the stem of the same or of an adjoining plant. 



The corn ear worm Heliothis (ChloHdea) obsoleta is of general 

 distribution and is mentioned as attacking cotton, tobacco, and In- 

 dian corn. In Japan there are two generations a year, the adults 

 of the first appearing in June and July and those of the second in 

 August and September. 



The cotton leaf roller Sylepta derogata (167) ranges in distribu- 

 tion from the southern islands of Japan to Chosen, China, Taiwan, 

 Australia, Burma, India, and Ceylon. In addition to cotton it at- 

 tacks a number of related plants such as hollyhock and hibiscus. 

 Though the caterpillars are common in Taiwan, the injury by this 

 species can not be considered great. The foliage of the American 

 varieties of cotton is affected frequently as much as 20 per cent, 

 whereas the Indian varieties are injured relatively only half as much 

 in the same localities. The larvae feed upon the under surface of 

 the leaf, and after the first molt this leaf is rolled ventrally. There 



