verde. The migration can be observed if one watches
at 1730-1800 hr during the months of July and Au-
gust. Some butterflies end their migration when they
reach the forested areas of the Monteverde commu-
nity; others continue flying over the mountains to the
Atlantic side, ending up in the San Gerardo area. A
few travel as far as the lowlands of San Carlos. Dur-
ing the next several months they begin moving west-
ward to higher elevations in the cloud forest. All fe-
males dissected during this entire time (July-April)
have been virgins in reproductive diapause. No eggs
or caterpillars have been found, further suggesting
that Manataria does not produce a second generation
either on the Atlantic slope or in the cloud forest,
despite the presence of suitable host plants. Finally,
in late April or early May, after nine months as adults,
they migrate to lower elevations on the Pacific slope
to breed again.4.5.4. Transparent Butterflies
Alan R. Masters
Butterflies with transparent wings are a common ele-
ment of the Monteverde forest understory. These
"clearwing" or "glasswing" butterflies belong to two
subfamilies of the Nymphalidae: Satyrinae and Itho-
miinae. A third clear-winged butterfly, Dismorphia
theucharila, is less common and belongs to a differ-
ent family (Pieridae). All groups have many species
with opaque wings. As with all nymphalids, clear-
winged nymphalids have four walking legs, in contrast
to the six walking legs in pierids. The two nymphalid
subfamilies are also easy to tell apart. Clear-winged
satyrines have transparent forewings, but the hind-
wing is translucent pink with a conspicuous eyespot.
Ithomiine clearwings are transparent on both the
fore- and hindwing with a definite border of black
or brown. Both groups fly near the ground in the
understory. Satyrines tend to be on the ground or fly
close to it. Ithomiine clearwings rest on leaves and fly
higher, usually no more than 2 m above the ground.
Pierids in the genus Dismorphia are the group on
which Bates (1862) developed his theory of mimicry
(see Sec. 4.5.5). Dismorphia spp. feed as larvae on
mimosoid legumes (e.g., Inga; DeVries 1987), but
host records for the only Central American clear-
winged species in the genus, D. theucharila, are not
reported. In Monteverde, D. theucharila is more com-
mon in Penas Blancas and is rarely encountered in
the community.
Cithaerias menander is the only clear-winged
satyrine in Monteverde; it occurs in Penas Blancas.
The transparent forewing of C. menander can appear
brown against the forest floor. The closely related
satyrine Pierella helvetica, also found in Monteverde,has opaque dark brown forewings. The two species
occur together and are often difficult to distinguish.
Both satyrines fly quickly along the ground, are diffi-
cult to capture, and are probably palatable to a wide
range of predators. Larvae probably feed on Maranta-
ceae and Heliconiaceae and adults on sap flows, rot-
ting vegetation, and fruits (DeVries 1987).
Monteverde has 11 clearwing species in several
genera (DeVries 1983). Including the Penas Blancas
and San Luis valleys, there are 17 species (W. Haber,
pers. comm.). Costa Rican ithomiine clearwings reach
their greatest diversity at middle altitudes (Haber
1978). Unlike satyrine clearwings, ithomiines fly so
slowly they often can be captured without a net. Un-
palatability of clear-winged ithomiines suggests the
transparent color, combined with a bold border and
some white markings, may be aposematic, though
perhaps only at close range. There are species of clear-
winged ctenuchid moths and opaque pierids in the
genus Dismorphia that mimic the clear-winged color
pattern using white and black scales. The frequency
of such mimics in Monteverde is low.
My research with ithomiine clearwings in Monte-
verde was to understand their chemical protection
(Masters 1990). All Monteverde clearwing species
feed as larvae on plants in the Solanaceae, although
ithomiines elsewhere feed on Apocynaceae and Ges-
nereaceae (Haber 1978). These plants are more com-
mon along roadsides and open areas, bringing itho-
miine clearwings out of the forest to oviposit. Although
these plants contain a plethora of secondary com-
pounds, none is sequestered by larvae (Brown 1984),
leaving them and recently emerged adults palatable
to predators. Adult ithomiines feed on nectar of many
flowers, but gain chemical protection against preda-
tors by visiting those containing pyrrolizidine alka-
loids (Brown 1984, Masters 1990, 1992), which are
most commonly found in the Asteraceae, Boragina-
ceae, caesalpinoid Fabaceae, and some orchids. In
Monteverde, it is common to see clear-winged itho-
miines feeding on the purple flowers of a low-
growing roadside aster, Ageratum sp. The majority
of visits to these flowers are by males. Pyrrolizidine
alkaloids are important to males as mate attractants.
Rarely, clear-winged and opaque ithomiines are
found clumped together in the forest, with pockets of
abundance that include 20 or more species and thou-
sands of individuals in a space of 10 m^2 (Drummond
1976). These "hot spots" may be breeding sites or leks
created by ithomiine males of many species (Haber
1978). Androconial hairs located between the fore-
and hindwing contain pyrrolizidine alkaloid deriva-
tives that are volatilized to attract females. Male ag-
gregations may be necessary to provide a critical
threshold of female attractant. Apparently, males pass120 Insects and Spiders