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

Parental Care on the Body
In several species of cockroach the protection and feeding
of young nymphs occurs while the offspring are clinging
to or attached to the body of the female. A simple
form of this type of parental care is exhibited by Blattella
vaga, an oviparous species that carries the ootheca until
nymphs emerge. The female raises her wings, allowing
freshly hatched nymphs to crawl under them. They appear
to feed on material covering her abdomen, then scatter
shortly afterward (Roth and Willis, 1954b, Fig. 65).
More complex forms of this behavior are found among
cockroaches in the Epilamprinae. Females in three genera
(Phlebonotus, Thorax, and Phoraspis) (Roth, 2003a) have
an external brood chamber, allowing them to serve as “armoured
personnel carriers” (Preston-Mafham and Preston-Mafham,
1993). The tegmina are tough and domeshaped,
and cover a shallow trough-like depression in the
dorsal surface of the abdomen, forming a space for protecting
and transporting the young. The aquatic species
Phlebonotus pallens carries about a dozen nymphs beneath
its wing covers (Shelford, 1906b; Pruthi, 1933) (Fig.
8.4). In Thorax porcellana the maternal behavior lasts for
about 7 weeks; 32–40 nymphs scramble into the brood
chamber immediately after hatch and remain there during
the first and second instars. Their legs are well adapted
for clinging, with large pulvilli and claws. It is probable
that nymphs feed on a pink material secreted from thin
membranous areas on the dorso-lateral regions of the
fourth, fifth, sixth, and seventh tergites of the mother. The
mouthparts of first instars are modified with dense setae
Fig. 8.3 (A) Newly hatched nymphs of Gromphadorhina portentosa
feeding on secretory material expelled from the abdominal
tip of the female (note left cercus). A new pulse of the
material is just beginning to emerge. The oothecal case can be
seen in the upper-right corner. Image captured from frame of
videotape, courtesy of Jesse Perry. (B) Four young nymphs of
Salganea taiwanensis feeding on the stomodeal fluids of the female,
viewed through glass from below. Note antennae of the
adult. Photo courtesy of Tadao Matsumoto.
elaborate forms of subsocial behavior include those
species in which morphological modifications of the
nymphs or the female facilitate parental care. Specializations
of the juveniles include appendages that aid in
clinging to the female, and adaptations of their mouthparts
to facilitate unique feeding habits. Some females
have evolved external brood chambers under their wing
covers, and others have the ability to roll into a ball, pill
bug-like (conglobulation), to protect ventrally clinging
nymphs. Maternal care is the general rule, biparental care
is recognized only in two taxa of wood-feeding cockroaches,
and male uniparental care is unknown.
Fig. 8.4 Female of Phlebonotus pallens carrying nymphs beneath
her tegmina. After Pruthi (1933).
SOCIAL BEHAVIOR 143