612 The Philippine Journal of Science 1923 



islands of the group are really rare exceptions. More detailed 

 records of these facts are given under General Distribution. 



BIOLOGY OF THE PACHYRRHYNCHIDES 



Very little is known concerning the biology of the pachy- 

 rrhynchids ; I have been able to discover the young stages of only 

 one species, Pachyrrhynchus confusus. This species is very 

 common in the swamp regions 4 at the foot of Mount Maquiling 

 in Laguna Province, Luzon, near the town of Los Baiios. This 

 fresh- water swamp is an extension of the large lake Laguna de 

 Bay. It is overgrown by a mass of coarse grass, shrubs, and 

 bushes, and also by a heavy growth of a peculiar fern, Acrosti- 

 chum aureum Linn. The water in the swamp varies in depth 

 from a few centimeters to half a meter or more at certain times. 

 Pachyrrhynchus confusus feeds on this fern. Adult specimens 

 are common during the entire year and seem to be rather long- 

 lived since at any time some specimens with soft elytra, others 

 with hard elytra of fresh appearance, and still others of old 

 worn appearance are found together climbing about on the fern 

 and on other plants in the swamp. The larvae were found 

 feeding in the soft parts in the older, lower part of the trunk 

 or caudex of the fern, which consists of alternating soft and 

 very hard tissues. Their burrows are very short. Not more 

 than two larvae were found in any one plant. The larvae are 

 oblong and of rather uniform diameter. 



The pupa was usually found in a crude pupal chamber near 

 the exterior part of the trunk. In general appearance the pupa 

 is rather elongate. The anterior margin of the clypeus and the 

 sides of the head are beset with a few bristles. The mesotho- 

 racic and metathoracic segments dorsad, somewhat laterad, are 

 beset with two thornlike tubercles. The abdominal segments 

 are also beset with a series of fleshy tubercles bearing a few 

 short bristles. The anal segment has, dorsolateral^, a more 

 projecting tubercle and several smaller ones, each bearing a 

 long bristle. The adults feed on the leaves of the fern, starting 

 at the edges, and usually devour an oval piece about 2 centi- 

 meters long. Pachyrrhynchus confusus has the same habit as 

 its allies; namely, the beetles, in climbing about and being ap- 

 proached, at first try to hide by crawling on the underside of 

 the leaf or on the reverse side of the stem. On being approached 

 very closely they instantly drop to the ground and remain mo- 



