The almost complete absence of field observations and knowledge of pneumorid behavior cited by Dirsh (1965) is largely a function of their patchy spatial and temporal distribution, probably in turn correlated with the availability of the appropriate food plants. This is particularly true for females, nymphs and alternative males which do not fly. The following natural history account is based mainly on extensive observation of Bullacris membracioides and Pneumora inanis in KwaZulu-Natal, and B. unicolor in Namaqualand, and less detailed observations of six other species.
Bladder grasshoppers are associated with relatively few food plants, an average of two food plants per species. These are mostly members of the Asteraceae, but also include representatives of Aizoaceae, Zygophyllacae, Rosaceae, Anacardiacae, and Lamiaceae. Food plants are important for the maintenance of crypsis by matching coloration, although exceptions occur in the occasional yellow-brown, B. membracioides, and in B. discolor,which has bright red, wings, legs and pronotum. Crypsis is further enhanced by fecal dispersal and inconspicuous eating patterns; e.g. for large leafed plants, animals eat only from the edges of the leaf in such a way that they minimize any change in its outline.
Nymphs and adult females are primarily diurnal in their activities, feeding in bursts during the day and sleeping at night. Oviposition occurs directly under the food plant in the common acridoid manner, with egg laid in pods 3-5 cm beneath the soil surface. Development time and relevant environmental signals are unknown but egg hatching appears to coincide with rains and the availability of ephemeral food resources. There are 4-6 instars, with males expanding at the final moult to attain the inflated form. These males are active at night, with different species stridulating at different times.
Adult males stridulate with leg and abdominal files to produce intense, species-specific mate location calls
amplified by the abdominal resonator. Females respond with wing-abdominal
or elytro-leg stridulation, producing a softer, less specific call which enables males to locate them by duetting. No complex courtship behavior has been observed. B. membracioides call at times when nocturnal, downward refracting temperature inversions create a tunnel effect with sound caught between the ground and zones of different temperatures, resulting in extremely large sound transmission distances of up to 2 km for the male signal (van Staaden & Römer 1997). This signal range is achieved by adaptations in the signal, behavior and sensory system of the animal which has the most sensitive hearing yet recorded for an insect (van Staaden & Römer 1998).
In captivity adult males are agonistic towards one another and will fight to the death, but females and nymphs tolerate higher densities. Male aggression does not extend to the alternative male morph in B. membracioides, suggesting that these are not recognized as rivals even though they remain in copula for extended periods of time. Proximate and ultimate causes for alternative male morphs are presently unknown.