With Further Notes on the Pyralid Moth Borer of Cane. 11 
Nature of Injury. 
The damage inflicted by this pyrale happens to be similar in 
external appearance with that caused by the noctuid moth-borer 
P. truncata Walk. ; a circumstance that may account for the occurrence 
of the former and of the Tineid in our canefields having been overlooked 
in the past. 
ts larvee, unlike those of the other two moth-borers, seldom attack 
the woody basal portion of shoots, preferring to tunnel higher up in softer 
parts of the stem. They rarely eat holes in the sides above the point of 
invasion, although frequently gnawing the internal tissue lying immedi. 
ately beneath the outer sheathing. 
A single irregular hole at the bottom of affected ratoons, but of 
larger diameter than that made by the T'ineid borer, generally denotes 
the presence of this pyralid moth. 
Many of the larvee collected were found tightly packed in the central 
decaying core, in such manner as would lead one to infer that this species 
requires very little air during its larval condition. 
Up to the present, infestations of Polyocha have been noticed by the 
writer on a plantation at Pyramid, near Cairns, 1915; in two localities 
at Meringa; and another at Pyramid during 1919-20. 
Description of Larva. (Fig. 9.) 
Light bluish-green, usually but not invariably suffused with pink. 
Thoracic segments pale sea-green with a few small irregular pink markings ; 
the first segment with a shining black plate bordered anteriorly by 
yellowish-green ; second segment with a centro-dorsal square greenish- 
brown blotch, clouded centrally with darker, and sometimes adjoining 
prothoracic plate. Pulsating line interrupted, dark-brown, conspicuous, 
margined on each segment by a sub-dorsal irregular greenish-white 
patch. Dorsal surface of abdomen pink; a row of triangular blotches 
on sides between spiracles and claspers, and numerous sub-dorsal 
suffused blotches greenish-white. Ventral area green suffused with 
pink. Head reddish-yellow, mouth parts blackish, ocelli, six in number, 
partly suffused with black blotches (Fig. 10). Body tapering abruptly 
towards either extremity; each segment bearing about 10 scattered 
long white hairs. Legs pale-green or yellow. Length, about 11 mm. 
(nearly half-an-inch). 
A few hours before pupation the colour fades, the larva becoming 
whitish instead of bluish-green, with abdominal blotches pale-blue, 
the prothoracic plate light yellowish-green, and the head very pale 
yellow. Some specimens become dark reddish in colour. 
Behaviour of the Larva. 
The caterpillar of this species, unlike that of the preceding, is nega- 
tively photo-tropic; that is, when exposed to view, it invariably tries 
to avoid the light by crawling, if possible, into the darkest portion of its 
tunnel. 
