Nycteribiidae and Streblidae are blood-feeding
parasites of bats. Larvae are retained within the female
fly's body until the end of the third instar, feeding on
secretions of a specialized female accessory gland.
Adults of both families are highly modified and
unusual in appearance; those of Nycteribiidae lack
wings. Hippoboscidae show a similar biology but
mainly parasitize birds.
The larvae of Notochaeta bufonivora (Sarcophagi-
dae) parasitize frogs and toads, and in the Monteverde
area, they attack Harlequin Frogs (Atelopus varius,
Bufonidae). The adult fly deposits 1-10 larvae in the
skin of the frog. The maggots first consume the thigh
muscles, then the internal organs, and eventually kill
the frog (Crump and Pounds 1985). How the maggot
contends with the potent neurotoxin present in the
skin of this brightly colored frog is unknown.
Flies include species that feed on other insects,
usually in the larval stage, although robber flies (Asili-
dae; Fisher and Hespenheide 1992), dance flies
(Empididae), and the small metallic green long-legged
flies (Dolichopodidae) are also predatory as adults.
Most predatory fly larvae are hidden in the soil, leaf
litter, or rotting wood. Among the few exposed on
vegetation are species of Syrphidae (see Sec. 4.5.3).
Several families of flies include parasitoids, insects
whose larvae live in intimate association with their
host and eventually kill it. The largest group of para-
sitoids is the Tachinidae, many of which attack lepi-
dopteran caterpillars. Other parasitoids include many
Bombyliidae (bee flies), some Phoridae (see Sec.
4.6.2), and Pipunculidae (big-headed flies).
4.6.2. Phorid Flies of Costa Rican
Cloud Forests
Brian V. Brown
Phorids have been called the most biologically diverse
family of insects on the planet. The life history of most
phorid larvae is unknown, but they can be predators,
scavengers, herbivores, parasitoids, parasites, and
commensals (Disney 1994). Phorid flies are small (1-
7 mm long) flies that occur worldwide; the greatest
diversity is found in tropical regions. Tropical phorid
diversity is compounded by the numerous species
associated with ants and termites. A single lowland
site in Costa Rica might contain 150 or more species
of a single ant-parasitoid genus (Brown and Feener
1995).
The phorid fauna of cloud forests is distinctive. It
is a mixture of lowland elements, middle-elevation
elements, and a few northern elements that extend
their range from the Nearctic region into the tropics
at higher elevations. Of special interest in cloud for-
ests are species that extend their ranges from the
Nearctic region through the Andes of South America
at middle to high elevations. In the Phoridae, two
such genera, Phora and Lecanocerus, are represented
by species that are the same as those found in North
America.
Typical of the lowland elements are the parasitoid
species, especially the large genus Apocephalus. Most
of these flies attack ants, and although they are much
less diverse in cloud forests than in the lowlands, they
are a large component of the cloud forest fauna. One
group of Apocephalus attacks leaf-cutter ants, forc-
ing them to carry ant "hitchhikers" that ride on the
leaves to protect against phorid attack (Feener and
Moss 1990). This can be observed in foraging columns
of the ant Acromyrmex octospinosus, which is at-
tacked by Apocephalus luteihalteratus. Another
well-represented group attacks injured or distressed
ponerine ants and can be lured by crushing a few ant
workers. The flies are quickly attracted by the produc-
tion of the ants' alarm pheromones (Brown and Feener
1991, Feener et al. 1996). Stingless bees are also
heavily used by phorid flies (Fig. 4.13). Species of
Melaloncha and Apocephalus (Mesophora) fre-
quently hover or perch near bee nest openings, dart-
ing at worker bees to parasitize them. By crushing
workers, one can attract flies of the genus Calamiscus,
which lay their eggs in the injured bees (Brown, in
press).
A group of Apocephalus in cloud forests in the
subgenus Mesophora does not attack ants but has di-
vergent hosts such as stingless bees, wasps, and can-
tharoid beetles (lampyrids and cantharids; Brown
1993,1996). Species richness of Mesophora is much
greater in cloud forests than lowlands, with up to 20
species known from a single site (Zurqui), the hosts
of which are poorly known. Army ant swarm raids
occur in the lower elevation parts of the cloud for-Figure 4.13. A female Apocephalus (ant-decapitating fly)
has landed on a prospective host, a male stingless bee.
Drawing by Jesse Cantley from a photograph by Brian V.
Brown.123 Insects and Spiders