1972 ] Young — Disnvorphia virgo 169 
oviposited in the field on young or old leaves. Developmental time 
on both young and old leaves was similar (no significant differences 
with t test) between the field and laboratory. 
At Bajo la Hondura, I. pittieri is most abundant along exposed 
river edges where it is a member of young second-growth plant com- 
munities. At Cuesta Angel, the plant is a member of the heavily 
shaded forest understory. At both localities the plant grows as a 
small woody tree, usually 1.5 to 4.0 m in height. Different annual 
patterns of leafing out may be a function of the type of plant com- 
munity in which the tree is found. Leafing out may have a different 
pattern at Cuesta Angel than it does at Bajo la Hondura, a factor 
influencing the egg laying habits of D. virgo and in turn, the de- 
velopmental time in different populations at various times of the 
year. 
Larval Behavior 
Perhaps the most interesting feature of the behavior of larval D. 
virgo is their apparent crypsis, both in morphology (coloration and 
form) and behavior (resting positions on the host plant). The larvae 
are thin and green and very difficult to find on the plant. The con- 
cealment is enhanced by their ventral positions on leaves and their 
use of large veins as resting sites (Fig. i-B, C, D). This combina- 
tion of morphological and behavioral crypsis might function to re- 
duce attacks by predators and parasites, Of a total of 13 young 
larvae (6 first instar, 3 second instar, 1 third instar, and 3 fourth 
instar) observed at Bajo la Hondura during late July and early 
August, on tagged host plants, all of these survived to the late fifth 
instar. Although this sample is small, the data suggest low predation 
and parasitism on larvae; fates of fifth instar searching for pupation 
sites and pupae in the field were not determined. Egg mortality has 
not been studied. Furthermore, since observations on larval mor- 
tality were confined to a relatively small portion of the year, it is 
not known if predation rates on larvae in this butterfly vary sea- 
sonally. 
Although as many as 5 eggs might be oviposited at different spots 
on a single leaf, larvae are never gregarious. When eggs are laid 
on older leaves, larvae feed at the edges and work their way inward 
as they grow larger. When eggs are laid on young leaves, larvae 
may begin to feed immediately on inner portions of the leaf. On 
older leaves, first instars can only eat part way through the leaf. 
On young leaves, first instars can eat all the way through the leaf 
tissue. Such a difference in feeding may affect the rate of food as- 
similation by the young larvae, thereby increasing or decreasing the 
