Cockroache; Ecology, behavior & history - W.J. Bell

Fig. 1.12 Perisphaerus semilunatus female: dorsal, ventral, lateral, and nearly conglobulated. Photos
by L.M. Roth.
1953); it is unknown whether that is the case in these
cockroaches.
The Burrowers
Cockroaches that burrow in wood or soil exhibit a remarkable
convergence in overall body plan related to the
ability to loosen, transport, and travel through the substrate,
and to maneuver in confined spaces. These insects
are often wingless, with a hard, rigid, pitted exoskeleton
and a thick, scoop-shaped pronotum. The body is stocky
and compact, and the legs are powerful and festooned
with stout, articulated spines that provide anchorage
within the tunnels and leverage during excavation (Fig.
1.13). The cerci are short, and can be withdrawn into the
body in Cryptocercus (thus the name) and Macropanesthia.
Long cerci make backward movement in enclosed
spaces inconvenient (Lawrence, 1953).
The similarity in the external morphology of Cryptocercus
and wood-feeding Panesthiinae is so striking that
they were initially placed in the same family (Wheeler,
1904; Roth, 1977). McKittrick (1964, 1965), however, examined
their genitalia and internal anatomy and demonstrated
that the resemblance was superficial. Her studies
resulted in placing the two taxa into distantly related families
(Cryptocercidae and Blaberidae). They currently offer
an opportunity to scientists interested in sorting the
relative influences of phylogeny and ecology in structuring
life history and behavior.
The Borers
Although little to nothing is known of their biology, several
small cockroaches have a heavy pronotum and exhibit
the elongated, cylindrical body form typical of many
wood-boring beetles (Cymorek, 1968). Their appearance
suggests that these cockroaches drill into solid wood or
Fig. 1.13 Adult Cryptocercus punctulatus. Photo courtesy of
Piotr Naskrecki.
soil because the shape minimizes cross-sectional area, reducing
the tunnel bore and the force required to advance
a given body weight. This morphotype is exhibited by
the genus Colapteroblatta (Epilamprinae) (Roth, 1998a),
as well as some species of Perisphaeriinae in the genera
Compsagis, Cyrtotria, Bantua, and Pilema (Shelford,
1908; Roth, 1973c). Compsagis lesnei typifies this type of
cockroach (Fig. 1.14) and is a small (9.5 mm in length)
African species found inside of tree branches (Chopard,
1952).
Desert Dwellers
Cockroaches that live in the desert typically have morphological
adaptations allowing for the conservation
of water and for ease in negotiating their sandy environment.
Adult females and nymphs are shaped like
smooth, truncated ovals, with short, spined legs (e.g.,
Arenivaga investigata—Friauf and Edney, 1969). The head
is strongly hooded by the pronotum, and cuticular extensions
of the thoracic and abdominal tergites cover the
12 COCKROACHES