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

Fig. 1.5 One of the largest and one of the smallest known cockroaches. Left, adult female of Megaloblatta
blaberoides from Costa Rica; the ootheca is that of Megaloblatta regina from Ecuador.
Right, female nymph of Attaphila fungicola; ventral view of specimen cleared and mounted on a
slide, courtesy of John Moser. Photos by L.M. Roth and E.R. Willis.
these taxa are long lived, requiring a sturdy body to
weather the wear and tear of an extended adult life (Kalmus,
1941; Karlsson and Wickman, 1989). They also can
be large-bodied insects, with allometric scaling of cuticle
production resulting in disproportionately heavy integuments
(Cloudsley-Thompson, 1988). The pronotum of
M. rhinoceros is 100 thick, and the cuticle of the sternites
is 80 , almost twice that of the tergites. The considerable
bulk of the abdomen normally rests on the ground,
thus requiring greater abrasion resistance (Day, 1950).
BODY SIZE
The general public has always been fascinated with “giant”
cockroaches. Discoveries of large species, whether
alive or in the fossil record, are thus guaranteed a certain
amount of attention. The concept of body size, however,
is qualitative and multivariate in nature (McKinney,
1990). Consider two cockroaches that weigh the same but
differ in linear dimensions. Is a lanky, slender species bigger
than one with a stocky morphotype? Neotropical
Megaloblatta blaberoides (Nyctiborinae) triumphs for
overall length (head to tip of folded wing) (Fig. 1.5). The
body measures 66 mm, and when the tegmina are included
in the measurement, its length tops out at 100
mm. This species has a wingspan of 185 mm (Gurney,
1959), about the length of a new pencil. Also in contention
among the attenuated, lighter-bodied cockroaches
are several in the oft-cultured genus Blaberus. Blaberus
giganteus may measure 80 mm overall (60 mm body
length) and female Blab. craniifer 62 mm. Pregnant females
of the latter weigh about 5 g (Nutting, 1953a). A
male Archimandrita tessalata measured by Gurney (1959)
stretched to 85 mm, and one of the largest species in West
Africa (more than 60 mm) is Rhyparobia ( Leucophaea)
grandis (Kumar, 1975). Recently, a large cockroach in the
genus Miroblatta was discovered in caves and rock shelters
in limestone formations in East Kalimantan, the Indonesian
section of Borneo. 1 The cockroach was widely
reported as being 100 mm in length (e.g., BBCNews, 23
December 2004). Two males measured by Drs. Anne Bedos
and Louis Deharveng were 60 mm, but they noted
that some specimens, particularly females, may be larger.
The cockroach is a streamlined, long-legged species that
moves very slowly on tiptoe, with the body elevated up
over the substrate. It is a beautiful reddish-brown, with
lighter-colored legs and wings that are about half the
length of the abdomen.
In the heavyweight division, the undisputed champs
are the wingless, burrowing types. The Australian soilburrowing
behemoth M. rhinoceros weighs in at 30 g or
more, and can measure 85 mm in length. Macropanesthia
rothi is sized similarly to M. rhinoceros, but is more robust
in the thorax and legs (Rugg and Rose, 1991; Walker et al.,
1. For information on the species, we thank Patricia Crane,
Leonardo Salas, Scott Stanley, and Louisa Tuhatu of the Nature
Conservancy, and Louis Deharveng, Anne Bedos, Yayuk Suhardjono,
and Cahyo Rachmadi, the entomologists in the expedition
that discovered the species. The cockroach was identified by P.
Grandcolas.
6 COCKROACHES