Psyche 
348 
[Vol. 93 
palp a cluster of 8 sensilla. Labium with a few minute spinules 
medially. Otherwise similar to second instar larva. 
Fourth Instar Larva. Length (through spiracles) 3.5-4 mm. 
Spiracle diameter about 0.013 mm. Body hairs 0.025-0.05 mm long, 
sparse, most numerous on T1 and AIX-AX. Head hairs 0.025-0.05 
mm long; some dorsal hairs curved downward, few ventral upward; 
about 100. Labrum bilobed and with sinuate lateral borders; with a 
few spinules medioventrally. Mandible with apical half tapering to a 
narrow sharp point and slightly curved medially. Maxillary palp a 
cluster of 7 sensilla. Otherwise similar to third instar larva. 
Fifth Instar Larva = Mature Larva. Length (through spiracles) 
4.4-12.1 mm. Spiracles about 0.025 mm in diameter. Entire integu- 
ment densely and coarsely spinulose, the spinules rather long and 
the rows so close together that the spinules overlap. Body hairs 
moderately numerous; 0.075-0.2 mm long, longest around anus. 
Cranium with entire integument spinulose, the spinules isolated or 
in rows. Head hairs 0.033-0.165 mm long; about 120; some ventral 
hairs curved strongly upward. Labrum with a few sensilla ventro- 
medially; spinulose, the spinules minute and isolated or in short 
rows, on all surfaces. Mandible with 3-4 small denticles on apical 
half. Maxilla broadly paraboloidal and appearing adnate, entire 
surface spinulose, the spinules isolated or in short rows; palp a 
slightly elevated sclerotized cluster of 8 sensilla; galea a small 
sclerotized cone with 2 apical sensilla. Labium with entire surface 
spinulose, the spinules isolated or in short rows. Otherwise as in the 
fourth instar larva. See our 1984: Fig. 9 on p. 271. 
Material studied: numerous larvae from Barro Colorado Island, 
Panama, courtesy of the late Dr. T. C. Schneirla. 
Our tentative conclusions are: 
1 . In each species instars may be distinguished by spiracle diame- 
ter; body hair length and distribution; head hair length and number. 
2. The two species are indistinguishable in the first and fifth 
instars. In the second instar they may be separated by a spiracle 
diameter; uniformity in length and distribution of body hairs; length 
and number of head hairs. In instar three: length and distribution of 
body hairs; length and number of head hairs. In the fourth instar: 
spiracle diameter; distribution and uniformity of length of body 
hairs. 
