1973] 
Young — Parides areas mylotes 
7 
poisonous Parides larvae which stand out against the foliage back- 
ground during the day time when they are feeding. This is an ideal 
situation for unpalatability to be effective against vertebrate preda- 
tors. The bird does not have to make tactile contact with the poten- 
tial prey, but can recognize it from a distance. On the other hand, 
the added possession of a defensive organ that produces a volatile 
chemical secretion would be an adaptation primarily against inverte- 
brate (arthropodan) predators that make tactile or very close visual 
contact with Parides larvae and elicit a behavioral response. Such a 
defensive mechanism would be essentially ineffective against verte- 
brate predators since the larvae could not respond fast enough to the 
strike of the predator, and the larva would invariably be killed. 
This is especially true since lepidopterous larvae have low visual 
sensing ability but quick discriminatory ability for tactile stimuli. 
In a similar fashion, the generally instinctive nature of the be- 
havioral repertoire of invertebrate predators would make unpalata- 
bility an ineffective defense mechanism against these predators. 
Under such conditions, there is strong selection for the evolution with 
a dual system of defense, one adapted to vertebrate predators with 
developed learning abilities (unpalatability), and the other adapted 
to smaller invertebrate predators with instinctive behavior patterns 
(defense glands). Furthermore, the larvae would probably survive 
single attacks by invertebrates such as ants, even though the in- 
stinctive nature of the predator’s behavior results in repeated attacks 
on the prey. The small size of invertebrate predators and the ability 
of Parides larvae to survive individual attacks (in the form of small 
bites) reduces the threat of death from instinctive predatory be- 
havior patterns. Thus, in the absence of conclusive evidence, I sug- 
gest that the unpalatable properties of troidine butterfly larvae (Euw 
et al., 1968) are an adaptation to potential large vertebrate preda- 
tors, while their defensive organs comprise an adaptation to inverte- 
brate predators. This effect is even more pronounced in the adults, 
which are very unpalatable to birds (Brower and Brower, 1964), 
since there are ample opportunities for foraging birds which catch 
insects on the wing to recognize, at a distance, the butterflies through 
conspicuous coloration. Therefore, adult butterflies should possess 
unpalatability rather than defensive gland as an adaptive strategy 
against vertebrate predators. The studies of Euw et al. (1968) and 
Eisner et al. (1971) indicate that unpalatability and chemical de- 
fense secretions in troidine butterflies are due to very different kinds 
of chemical compounds. 
The oviposition behavior varies greatly for different genera of 
