128 The Philippine Journal of Science wis 



LIFE HISTORY 



Egg. — The eggs (Plate I, fig. 1) of Promecotheca cumingii 

 are deposited singly oti the underside of the leaflets and gen- 

 erally on the lower leaves of young palms. The beetle eats a 

 small hole through the lower epidermis of the leaf, leaving the 

 edges of the hole very rough. The egg is inserted in this hole, 

 and cemented in place with a yellowish glutinous secretion which 

 turns dark brown upon hardening, and resembles dried leaf- 

 tissue. During this process the abdomen of the insect is moved 

 with a rotary motion. After resting over the egg for a few 

 seconds, the beetle moves away and begins feeding again. In 

 several cases after the egg had been cemented in place, the adult 

 was observed to pat it with her front feet. 



The eggs are flat, semielliptical, brownish bodies shaped some- 

 what like a pumpkin seed. The outer surface or covering is 

 very rough, and the eggs are very easily broken when this 

 protective substance is removed. They are about 1.5 millimeters 

 in length; 1 millimeter in width; and 0.3 millimeter in thickness. 

 The period of incubation of 286 eggs averaged 13.5 days, of 

 which the maximum was fifteen and the minimum thirteen days. 



Larva. — Upon hatching, the larva (Plate I, figs. 2 and 3) eats 

 its way through the egg wall and directly into the tissue of the 

 leaflet where it spends its entire larval and pupal stages and 

 is somewhat protected by the lower and upper epidermis of the 

 leaflet. The larvee are fleshy footless grubs, and average about 

 1.2 millimeters in length when newly hatched. The head is the 

 largest segment; it is a translucent, shiny brown, and wedge- 

 shaped with rounded sides. The mandibles are black, and can 

 be drawn under the labrum. Two brownish lines form an X on 

 the back of the head. Two whitish lines extending under the .1 



head-cast near the apex give it the appearance of an arrowhead. 

 These markings are absent in later stages. In the older larvae 

 the head is slightly smaller than the following segment; the 

 body is cream colored and semicylindrical, tapering from seg- 

 ment 1 to segment 11; the anal segment is about one-half the 

 size of segment 1. Segment 1 is depressed anteriorly. Segments 

 1 to 11 are protruded into tubercles on both sides which give 

 rise to setae of 6 hairs each. 



The average length of the full-grown larva is 9.54 millimeters, 

 and the average width of the head cast is 1.54 millimeters. The 

 average time required in the larval stage is thirty-two days; 

 twenty-eight of these are spent in feeding and developing, and 

 four days without feeding, during which time the larva changes 



