i6 
Psyche 
[March-June 
The inability of young larvae of P. areas mylotes to survive on 
Aristolochia ringens, A. littoralis, A. gigantea, and A. veraguensis 
may be due to the lack of evolutionary contact (Ehrlich and Raven, 
1965) with these plants. An alternative explanation is that extreme 
food plant specialization in the butterfly has resulted in the narrow 
restriction to only a few species of Aristolochia locally. Until more 
is known about the regional and geographical distribution of various 
species of Aristolochia in Central America, it will be difficult to 
resolve the question of larval food plant adaptability in Parides. 
Unfortunately eggs from La Selva have not been reared on A. con- 
stricta from Tirimbina nor the converse, namely, eggs from Tirim- 
bina reared on A ristolochia sp. from La Selva. 
The question of unpalatability is of considerable ecological and 
evolutionary interest. Brower and Brower (1964) have demon- 
strated that freeze-killed adult Parides neophilus L., which feeds on 
various species of Aristolochia on Trinidad, are very unpalatable to 
Scrub Blue Jays in the laboratory. Brower and Brower (1964), 
Ehrlich and Raven (1965) and Pfeifer (1966) cite previous studies 
which illustrate the toxic properties of various compounds derived 
from the vegetative portions of Aristolochiaceae. The question of 
palatabifity in genera of the Troidini ( Parides , Battus , Ornithop- 
tera, and Troides ) is of interest since the larvae are presumably 
unpalatable in addition to possessing a defensive organ (Eisner et. al., 
1971). The larvae of these genera, as exemplified in the present 
study by P. areas mylotes , are generally conspicuous in appearance 
(Fig. 2, 3) to the human observer. 
The possession of a dual system of defense by Parides larvae and 
other troidines is related to the functional responses of each com- 
ponent (unpalatability and chemical defense secretion) to different 
kinds of predators that the larvae encounter in their habitats. Un~ 
palatability, as evidenced here by the conspicuous coloration of the 
larvae and the toxic properties of their food plants, is an adaptation 
for defense against vertebrate predators such as insectivorous birds, 
mammals, and reptiles. Brower and Brower (1964) have demon- 
strated that blue jays become ill after eating an unpalatable butterfly 
and that there is a subsequent modification in prey-selection behavior 
by such an experienced predator to avoid the prey on further visual 
contact with it. Thus, the flexible learning abilities of vertebrate 
predators makes unpalatability an effective defensive mechanism that 
increases the likelihood of survival of individuals in a prey popula- 
tion. An insectivorous bird foraging in forest edge second-growth or 
forest canopy has daily opportunity for visual contact with the 
