Further research is needed to explain these pat-
terns. For example, why do the Ophioninae show great-
est species richness in lowland Costa Rica whereas in
Borneo they are most species rich in montane cloud
forests? We should also test the prediction that the
hosts of the parasitoids of flies also increase in diver-
sity in cloud forests. In terms of conservation, the
leading specialist of the fly parasitoids of the super-
family Prototrupoidea stated: "I am absolutely ada-
mant about one thing, in that the cloud forest procto-
trupoid fauna is the richest belt anywhere in the
neotropics, much richer than the fabled Amazonia.
This observation may be a strong argument in favor
of protection of this precious treasure" (L. Masner,
pers. comm.). Minute parasitic wasps that attack fly
larvae living in leaf litter lack appeal for most biolo-
gists and consequently attract few researchers. As a
consequence, extinctions may go unnoticed.
4.7.3. Eusocial Wasps (Vespidae:
Polistinae)
Sean O'Donnell
In the New World, the family Vespidae comprises four
subfamilies: Eumeninae, Masarinae, Polistinae, and
Vespinae. The first two are solitary wasps (each fe-
male builds and provisions her own nest and lays
eggs); the latter two are eusocial (females cooperate
in rearing the brood, show a division of labor, and
usually only the queen lays eggs). Eusocial wasps
often build their colonial nests from masticated wood
fibers (hence the name "paper wasps") but are better
known for their painful sting, with which they defend
the nest. The subfamily Vespinae (the hornets and
yellow jackets of North America) does not occur
south of Guatemala, whereas the Polistinae are found
throughout the New World.
Eusocial wasps exhibit one of two social structures:
(1) independent founders, where one or more repro-
ductive females initiate new colonies without the aid
of workers (Gadagkar 1991, Reeve 1991), or (2) swarm
founders, where colonies are initiated by groups of
queens and workers that move in a coordinated man-
ner to new nest sites (Jeanne 1991). Independent
founders' nests consist of a single comb of naked cells
and are suspended from the substrate by a narrow
stalk; their colonies are typically small, comprising
up to a few dozen adults. Swarm founders' nests have
a more complex architecture, usually enclosed in an
envelope (Jeanne 1975), and are populated by hun-
dreds or thousands of adults (Fig. 4.16). In Monte-
verde, independent founders include Polistes and
Mischocyttarus; swarm founders include Agelaia,
Epipona, Polybia, and Synoeca (Appendix 7).Figure 4.16. Polybia occidental!* wasps guarding
their nest. Photograph by Gregory Dimijian.129 Insects and Spiders