78 
Psyche 
[September 
gust (and maybe at other times of the year) and this may be a fur- 
ther indication of its non-participation in the mimicry complex. 
(6) From observations of selective advantage associated with ovi- 
position on young leaves of host plants by herbivorous insects, in- 
cluding butterflies, it is suggested that an interesting question to be 
investigated is the possibility of the occurrence of a shifting palata- 
bility spectrum within a local insect population, which oscillates be- 
tween different levels of palatability at different times of the year. 
Such a hypothesis assumes differences in the leaf compounds which 
endow the palatability properties of a species, between young and 
old leaves of the host plant in question, and also assumes that insects 
obtain their palatability at least in part from their host plants. 
Acknowledgements 
This research was supported through a College Science Improve- 
ment Grant (GY-4711) awarded to Lawrence University. I was 
assisted in the field and laboratory by Patrick Eagan (Lawrence). 
The Associated Colleges of the Midwest in San Jose provided lab- 
oratory facilities and logistic support. Luis Diego Gomez (Museo 
Nacional de Costa Rica) identified the larval host plant. 
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