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Psyche 
[Vol. 88 
years. However, when the number of colonies included in any 3-day 
interval for any of the combinations dropped below five, we 
discontinued summarization of the data for that combination, since 
average caste compositions based on less than five colonies would 
have little meaning. 
Examination of Symbiotic Protozoa 
Fourth stage or older larvae from five of the R. virginicus male + 
R. flavipes female pairing and from four of the R. flavipes male + 
R. viginicus female pairing were examined for the presence of 
species-characteristic protozoa. R. flavipes contains mainly Dine- 
nympha fimbriata Kirby, D. gracilis Leidy, Pyrsonympha major 
Powell, P. vertens Leidy, Spirotrichonympha flagellata (Grassi) and 
Trichonympha agilis Leidy. R. virginicus contains fewer species of 
protozoa, with the primary species being D. fimbriata, P. minor, S. 
flagellata, and T. agilis (Yamin, 1979). 
Results 
Egg and Larval Development 
The time to the first appearance of eggs and larval instars was 
rather similar for four of the seven combinations examined ( R . 
flavipes male + R. flavipes female, spring; R. virginicus male + R. 
virginicus female; R. virginicus male + R. flavipes female; and R. 
virginicus female + R. virginicus female; see Table 1). Egg 
production began in these combinations about 8 to 15 days after 
pairing, and the first larvae were produced in about 38 to 45 days. 
Fourth stage larvae were present by about 75 days after pairing. 
In contrast, the fall R. flavipes male + R. flavipes female 
combination required almost 25 days for egg production to begin 
and almost 60 days for the first larva to be produced. Fourth stage 
larvae were present by 83 days after pairing. The combination of R. 
flavipes male + R. virginicus female began egg production within 15 
days of pairing, but only one larva was ever produced from this 
cross. This larva appeared normal and successfully molted twice 
(Table 1). Although the R. flavipes female + R. flavipes female 
combination was prolific in egg production, none of these eggs ever 
hatched. 
Soldier Production 
The proportion of incipient colonies producing soldiers in the 
