42 THE SUGAR-CANE INSECTS OF HAWAII. 
probably to escape from parasites, many of which prey upon them. Theretreat which 
it constructs is undoubtedly for the same purpose, as well as for protection from wasps 
and birds which prey upon it. 
The caterpillars are full grown in about three weeks from hatching. They molt 
five times at intervals of about three to five days, and five to seven days between the 
fifth molt and the spinning of the cocoon and pupation. Pupation takes place within 
a slight cocoon of white silk in the “retreat’’ where the caterpillar has lived; how- 
ever, the cocoon is sometimes made beneath the leaf-sheaths of cane, and in other 
favorable places. 
CONTROL MEASURES. 
No special remedies are employed in cane fields against this pest. 
Swezey suggests that in fields of young cane a spray of Paris green 
or arsenate of lead might be used with effect, and mentions that at 
times laborers have been sent over the field to pinch the caterpillars 
in their-retreat between the folded cane leaves. 
PARASITES. 
The species is attacked, fortunately, by several introduced para- 
sites. Regarding the natural enemies of the species of moths belong- 
ing to the genus Omiodes, Mr. Swezey reports as follows on pages 36 
and 37 in his article above referred to: 
Omiodes caterpillars are attacked by a large number of species of parasites, some of 
which are native, and several which are the most valuable have been introduced. 
The most of the species are kept in check by their natural enemies, so that they do 
not become very numerous; in fact, several of them are very rare. Two species feed 
so numerously on cultivated plants that they become serious pests; accepta on sugar 
cane, and blackburni on palms. These two species are preyed upon very extensively 
by the parasites and checked considerably, but not sufficiently to keep them from 
doing considerable injury in certain localities and at certain seasons. Apparently the 
moths are more prolific in the winter months (about December to March) and the 
parasites are scarcer owing to their having had fewer caterpillars for them to keep 
breeding on during the preceding summer. Hence, when the winter broods of cater- 
pillars appear, there may be two or three generations of them before the parasites 
breed up to sufficient numbers so that they produce any noticeable check on the 
number of the caterpillars; then in another generation or two the caterpillars may be 
much reduced in numbers and a large percentage of them found to be parasitized; for 
example, on one occasion 75 % of the cane leaf-rollers in a field at Hutchinson plan- 
tation, Hawaii, were found to be destroyed by one species of parasite; at Olaa plan- 
tation, Hawaii, in a certain field, on one occasion a much higher percentage of them 
than that were killed; in Honolulu, of a large number of the palm leaf-roller cater- 
pillars collected, 90 % were parasitized. 
Since there are so many species of parasites preying on the leaf-rollers which are 
pests, it might be asked ‘‘ Why do they not become exterminated, or at least cease to 
be pests?”’? Apparently, with all of the parasites, they are still not numerous enough 
to overbalance the prolificness of the pest, even though they do kill such high per- 
centages of them at times. Since so many are killed by parasites, and yet there are 
enough left to do considerable injury at times, one cannot help but wonder to what 
extent these pests might increase were there no parasites preying on them, and how 
many times more serious would be the damage done by them. The extreme difficulty 
and impracticability of treating sugar cane fields, or large palm trees, artificially, for 
