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And babies make 31

January 7, 2019

I will never know the discomfort (or not) of carrying a child when the temperature outside tops 40C but I would imagine that I would be spending a lot of time inside under the air-conditioner whether it be at home, the library or shopping mall. Animals don’t have that option.

In the baking heat during a rest stop on a bike ride I spied this Australian Native Cockroach (Ellipsidion sp.) pictured left, spending time on the apparent search for something. Closer examination of the insect revealed it to be a female carrying an ootheca (egg case), the pale brown mass under the wings (pictured below).

The male and female cockroach mate end  to end.  The female then produces an ootheca that contains between 20 and 30 eggs, each egg being surrounded by air space. The oothecae when formed are soft but harden upon exposure to air. They are carried around until a suitable spot is found to deposit it, usually in a bark crevice. When hatched the instars look similar to the adult (pictured right) but without fully formed wings or genitalia. The life cycle proceeds through several instar stages until the final moult (ecdysis) when the adult emerges. The adult is initially white (pictured below left) but develops colouration over the space of several hours.

But at the start of this cycle spare a thought for the Mum wandering through the bush on those hot days with 30 eggs on board.

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