cies of Megalopinus, Lordithon, Bolitogyrus, and
Plociopterus, some species of Platydracus, and a
few species of Paederominus and Philonthus. Many
smaller Aleocharinae (athetines, bolitocharines, and
others) are attracted to mushrooms in the later stages
of decay and are primarily predators and specialists
on this habitat.
Species of Oxyporus are relatively large staphylin-
ids (1 cm or more in length) that are often strikingly
colored found primarily on fleshy mushrooms. The
only species that occurs in Monteverde, O. bierigi,
occurs on gilled mushrooms of the genera Pholiota
and Gymnopilus (Cortinariaceae). Little is known about
the life history of gyrophaenines and other mushroom-
inhabiting staphylinids in Monteverde. Overviews of
the biology of mushroom inhabiting staphylinids are
in Ashe (1984,1986,1987), Leschen and Allen (1988),
and Newton (1984).
Species of the aleocharine genus Tachiona are
found on the inside of webs that cover hepialid (Lepi-
doptera) burrows on living Trema (Ulmaceae) trees.
The flattened larvae and black-and-red adults of Tachi-
ona monteverdensis are abundant on the insides of
these webs and around the hole that contains the moth
larva. Virtually every active burrow contains a few
beetles, and sometimes 20-25 individuals can be
found in a single web. These beetles were considered
extremely rare until their association with hepialid
burrows was discovered at Monteverde (Ashe 1990).
Members of the aleocharine genus Charoxus are
small, elongate, subcylindrical beetles that are usu-
ally found in the fruits (receptacles) of figs. Little is
known about their biology, but they apparently enter
the fig through the exit hole chewed by male fig wasps.
The adults lay eggs in the fig and larvae mature be-
fore the fig drops from the tree. The staphylinids may
feed on emerging fig wasps, although all of the larvae
that I have examined had their guts filled with fig
pollen. Adult Charoxus are not found on fig trees
before the fig wasps begin to emerge, but adults and
larvae may be abundant in figs of the correct age. It is
not known how the adult staphylinids arrive at fig
trees precisely when fig wasps begin to emerge.
4.4.3. Dynastine Scarab Beetles
of Monteverde
Brett C. Ratcliffe
Beetles belonging to the Scarabaeidae are well known
because of their beauty, fascinating life histories, of-
ten bizarre body forms, and occasional economic sig-
nificance. There are 13 subfamilies and 400 (over 800
estimated) species of Scarabaeidae in Costa Rica; 62
of these species belong to the subfamily Dynastinae.
This subfamily contains species with magnificenthorns, which has given rise to the common names of
elephant, unicorn, or rhinoceros beetles for the en-
tire group. Most species of dynastines, however, are
smaller June beetle-like insects that lack horns. Adult
scarabs are readily distinguished from other families
of beetles by the presence of segmented antennae ter-
minating with a lamellate (platelike) club of three to
seven leaflike segments that can be expanded fanwise
or folded compactly together. Scarabs sense odors
with their antennae, and the enlarged "club" increases
the surface area of the sensory receptors.
Within the subfamily Dynastinae, there are eight
tribes containing about 1400 species worldwide
(Endrodi 1985). Six of these tribes occur in Costa Rica,
and five are represented at Monteverde. Of the 31
genera of Dynastinae found in Costa Rica, 13 occur at
Monteverde. Of the 62 species of Dynastinae found
in Costa Rica, I have found 36 at Monteverde. Prob-
ably no species of dynastine is endemic to Monte-
verde, although Cyclocephala williami (Fig. 4.10,
panel 4) is known only from the Monteverde area
(Ratcliffe 1992).
Altitudinal gradients of dynastine species occur in
the Monteverde region. Some dynastines (e.g., Golofa
spp.; Fig. 4.10, panel 9) are found only in the higher
wetter areas, whereas some species of Cyclocephala
are found throughout the area, at all elevations.
Dynastes hercules (Fig. 4.10, panel 8) is the largest
beetle found at Monteverde; males reach a length of
18 cm. Males have smooth, grayish green wing
covers mottled with black spots, and a shiny black
head and thorax, each of which bears a long, forward-
projecting horn. Females have roughened black wing
covers and lack horns. In tropical America, this spe-
cies is generally restricted to lower montane and
premontane rain forests above 1000 m.
Adults of nearly all dynastines are active at night
and frequently come to lights. During the day, the
adults hide beneath leaves and logs, or in the soil. The
adults of many Cyclocephalini (Fig. 4.10, panels 2,3,
5) feed at night on the flowers of plants, including
palms and aroids. Cyclocephala and Erioscelis feed
on the small flowers of the club-shaped spadix ofPhilo-
dendron and Diffenbachia (Color Plate 2) species
(Araceae; Young 1986,1988, Gottsberger 1989, Gotts-
berger and Silberbauer-Gottsberger 1991). Adults be-
longing to the other tribes occasionally feed on rot-
ting fruit or sap flows at night.
Sexual dimorphism is well developed in the horned
species. Males are larger and often possess huge, curv-
ing horns arising from the head and/or thorax. Horns
in scarab beetles occur in a wide array of shapes, forms,
and sizes (Arrow 1951). Only males have horns, which
suggests that they play a role in sexual selection. The
males of some dynastines fight over suitable feeding111 Insects and Spiders