A Large South Australian Insect

The South Australian Naturalist, 1923, p. 104

By Arthur M. Lea, F.E.S.

(Contribution from the South Australian Museum.)

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Fig. 2.
Our largest South Australian insect, or at least the one that, with legs and wings extended covers the greatest space, is undoubtedly the female of our beautiful walking-stick, or leaf-insect, Tropidoderes childreni; it sometimes measures nine inches in length, and the same in width, but the average is about eight inches. In bulk of body and in weight, however, it is exceeded by females of our large timber-moth, Zeuzera affinis, and in other parts of Australia there are still larger insects.

With wings folded it appears of a uniform pale green, and harmonises perfectly with the eucalyptus foliage, amongst which it moves, and upon which it feeds. The front wings are rather small, green above, tinged with red below, and almost of an even consistency; but each of the hind wings appears to be in two parts, a front part like the front ones in thickness, and a hind part that is much larger, thinner, and of a very pale, shining green; the thicker part has a conspicuous red patch near the base, and its under-surface is mostly red; there is also a purple patch where the wing joins the hody; the red and purple are entirely concealed when the wings are folded. The middle and hind legs, and the sides of the mesothorax (the part of the body to which the front wings are attached) are closely set with short spines or teeth, giving them a saw-like appearance.

The male differs from the female in being much smaller, with longer and much thinner legs, longer antennae and smaller wings, the front pair usually with a narrow whitish stripe; the tip of its abdomen is also without a canoe-shaped appendage, that is very conspicuous in the female.

Egg-laying begins soon after mating, and is continuous during the life of the female, the eggs being simply allowed to drop to the ground when ready; each egg is about the size of a grain of wheat, and has a curious cap-like attachment at one end; the newly-hatched larva is of a very pale green, with thin, spidery-looking legs; when nearing maturity four budding wings become evident, and later these change to the full wings of maturity.

The species ean fly, but as with others of the family, seldom does so, the female even less readily than the male.

It occurs in Victoria and Western Australia, as well as in our own State, and is eaten by magpies, crows, and other fairly large birds; but the great reduction in its numbers as compared with former years, is supposed to be due to the sparrow.

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