THE IMPORTED CABBAGE WEB WORM. 33 
almost without exception, ignorant of methods of control, and as a 
result much of the crop is injured and the growers become discour- 
aged and plant other crops which are less damaged by insects. 
Among these insects are the common cabbage worm (Pontia rapce 
L.), the imported cabbage webworm (Hellula undalis Fab.), cut- 
worms (Agrostis crinigera But!.), a looper (Autographa precationis 
Guen.), the diamond-back moth (Plutella macidipennis Curtis), the 
jeet army worm (Caradrina exigua Hiibn.) , the cabbage aphis {Aphis 
brassicce L.), the spinach aphis (Rhopalosiphum dianthi Schrank), 
and a number of minor pests. Among the latter is a leaf-miner 
(Agromyza diminuta Walk.), an unidentified species of thrips, and 
the melon fly (Dacus cucurbitce Coq.). The larvae of the melon fly 
work in cabbage which has previously been injured by the larvae of 
Hellula undalis. This fruit fly is an exceedingly destructive enemy 
of cucurbits, and its occurrence in cabbage is rather uncommon. 
The operations in Hawaii occupied a period of about seven months 
(July, 1910, until February, 1911), and during this time the insects 
affecting cabbage were kept under fairly constant observation. Dur- 
ing this period the imported cabbage webworm apparently caused 
more damage to cabbage than any other insect. The growers claim, 
however, that from January to April the common cabbage worm 
(Pontia rapce L.) is the most troublesome pest. During the period 
of actual observation, however, the webworm appeared to outrank 
the other species in destructiveness ; in fact, at least a few of the web- 
worms could be found whenever a search was made for them, although 
cabbage and turnips were the only crops which were noticeably 
damaged. The most serious infestation observed in 1910 occurred at 
Wahiawa : Oahu. On October 10, in company with Mr. E. M. Ehr- 
horn, a visit was made to a grower at Wahiawa, who planned to grow 
about 7 acres of cabbage that season. At this time he had three seed 
beds containing thousands of small cabbage plants. In one bed many 
plants had been killed, and of those which remained fully 75 per 
cent were infested by webworms and were worthless. In the other 
two beds in another field, at a distance of about 200 yards from the 
first, about 10 per cent of the plants were infested. The larvae in the 
seed beds were all small. On large cabbage plants in a garden, a 
mile or more from the seed beds, full-grown larvae were found in 
moderate numbers. One moth was observed, but no eggs were seen. 
In small garden patches at this place the Japanese killed occasional 
larvae which lived in folded leaves or between two leaves, by crush- 
ing them with the fingers. Apparently only larvae of conspicuous 
size were found, and as the majority of the webworms mined into the 
plants, beyond the reach of hand-picking, this method of control 
seemed of doubtful value. 
