letting nature back in

Perhaps because Bladder Grasshoppers are active at night, they are heard rather than seen. The call of the male Bladder Grasshopper, something between a bleat, a shriek and a croak, is alarmingly loud.

As I so seldom see them, I was surprised to see this Bladder Grasshopper perched on the stem of a small tree late one afternoon. Its attractive lemon-yellow colour was beautifully backlit by the light of the setting sun.

Initially I thought it was a Katydid or Bush-cricket, but I later learnt that whereas Katydids characteristically have long filament-like antennae, Bladder Grasshoppers have short antennae and, hence, are part of the group referred to as short-horned grasshoppers.  The family name of Bladder Grasshoppers is Pneumoridae.

Female Bladder Grasshoppers do not have wings, and therefore I deduce that the one I photographed is a male as the wings are well developed. This male has an inflated abdomen. Interestingly, in some species of Bladder Grasshoppers there are two forms:  in one form the males have inflated abdomens, and in the other the abdomens are not inflated

Although in both forms mature males call to attract females, the extremely loud and raucous call is made by males with inflated abdomens, which amplify the sound. A male Bladder Grasshopper makes the sound by stridulating, rubbing rasps on its hind legs over ridges on the abdomen to emit his ear-splitting calls. If not masked by other sounds, the nocturnal call of a male Bladder Grasshopper can be heard over a distance of nearly two kilometres (1¼ miles). This is the longest calling distance recorded for an insect.

In this photo, the ridges or knobs on the abdomen, over which the male rubs rasps on his hind legs when stridulating, can be seen 

When the male attracts a female she responds with relatively soft calls. The male approaches and they call and respond in duet and in so doing pair bond prior to mating. Females lay eggs in pods that are buried beneath the surface of the soil. Hatchlings are small and wingless and are referred to as nymphs. At successive stages of their development they moult (shed their skins). Grasshopper species moult 5 or 6 times before reaching their adult form.

Although a nymph and not yet an adult, this Katydid shows the long filament antennae and long back legs in contrast to the short antennae and hind legs of the Bladder Grasshopper

Bladder Grasshoppers (Pneumoridae) occur mostly in southern Africa and mostly in the coastal regions, but some species occur in the eastern coastal regions of Africa as far north as Uganda. The largest genus is Bullacris, represented by the grasshopper in this photograph. Mostly they are green in colour but there is quite a bit of colour variation, including the yellow with darker brown patches as seen in the individual I photographed. I think it is likely to be a Bullacris membracioides, a species that occurs in KwaZulu-Natal.

Sources: Donelson, Nathan C., Smith, Adam R. & Van Staaden, Moira J. 2008. Variation in adult longevity in a polymorphic grasshopper species. Journal of Orthoptera Research 17(2): 270-282;  Wikipedia. 2018. Pneumoridae. https://en.wikipedia.org/wiki/Pneumoridae;  Van Staaden, Moira J. & Römer, Heiner. 1997. Sexual signalling in Bladder Grasshoppers: Tactical design for maximising calling range. Journal of Experimental Biology 200, 2597-2608.

Posted by Carol