A DESCRIPTION OF 
THE LARVA OF THYCE HARFORDI CASEY 
(SCARABAEIDAE: MELOLONTHINI) 
By Terry L. Erwin 
Museum of Comparative Zoology 
Mating flights of Thyce harfordi Casey adults were first noticed 
in San Jose, California in 1962. In subsequent years many adult 
beetles were collected, but attempts to excavate larvae proved un- 
successful until J. Gordon Edwards, Richard Penrose, and I found 
two specimens. These were destroyed in the mail when we sent them 
to P. O. Ritcher at Oregon State University. The following year, 
Charles Baker, Toby Schuh, Edwards, and I returned to the cherry 
orchard the larvae were taken from previously. This trip in May, 
1 965 , proved successful in our search for one of the few large scarab 
genera with undescribed immature stages. 
Five or six excavations were made, each one adjacent to a randomly 
chosen cherry tree. The holes were dug to a depth of six feet and 
were from five to eight feet square. Even with this amount of 
digging, only eleven larvae were found (two were so badly damaged 
by the shovel that they had to be discarded). 
These larvae are here described and a key (for larvae) to the 
known genera of the Tribe Melolonthini is offered. For the most 
part, I have tried to follow the style and format used by Ritcher 
(1966) in order to make this single description fit into that author’s 
excellent and recent work on white grubs and their allies. 
Tribe Melolonthini ( sensu Ritcher) 
Key to genera with known immature stages, third instar 
1. Palidia present (fig. 5) 2 
1'. Palidia absent (in part) Phyllophaga Harris 
Figs. 1-7. Thyce harfordi Casey, la. Head capsule, frontal aspect, lb. 
Ultimate and penultimate antennal articles, proximal aspect. 2. Abdominal 
spiracle, 4th segment left side. 3a. Prothoracic leg, left lateral aspect. 3b. 
Prothoracic claw, caudal aspect. 4a. Left maxilla, dorsal aspect. 4b. Maxil- 
lary stridulatory teeth of left maxilla, dorsal aspect. 5. Raster, ventral 
aspect. 6a. Left mandible, dorsal aspect. 6b. Right mandible, dorsal 
aspect. 7. Epipharynx, proximal aspect. Symbols used: cpa, chaetoparia; 
dp, dexiophoba; h, heli ; lu, unci of lacinia ; pe, pedium ; pi, plegmata; 
pla, palidium; sd, maxillary stridulatory area. 
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