Forest Insects of Australia

By
WALTER W. FROGGATT, F.L.S.,
Government Entomologist, New South Wales.

Member of the Linnean Society of London, The Association of Economic Entomologists of U. S. America, Corresponding Member Entomologiska Foreningen of Stockholm, Vice-President of the Linnean Society of New South Wales, Vice-President of the Royal Zoological Society of New South Wales, Vice-President of the Wild Life Preservation Society, Vice-President of the Gould League of Bird Lovers, Vice-President of the Field Naturalists' Society, President Wattle Day League.

Illustrated with two coloured plates, 44 full plates, and 33 text blocks.

PRICE 7s. 6d.

Published under the direction of the Forestry Commissioners of New South Wales.

Wholly set up and printed in Australia by
Alfred James Kent, Government Printer, Phillip Street, Sydney, N.S.W. - 1923.

PREFACE.

As a worker in the field of Entomology, Mr. Walter W. Froggatt needs no introduction, and his compilation of this little volume on the “Forest Insects of Australia” is not the least valuable of his contributions to Science during the past thirty years. In this work will be found a fund of information regarding white ants, timber borers, and forest insect pests, which is of both practical and scientific value, and embodying, as it does, the results of many years' careful investigation, it may he accepted as a text and reference book of value by those interested in Forestry, Architecture, or industries in which wood as a material is employed.

The extent of injury done to timber by insect pests is hardly realised, and if the economic loss could be estimated, it would arouse the public mind from its apathy in regard to both the introduction of borer and other pests from abroad, and to the urgent need for protective and remedial measures. The matter is one which demands the serious attention of our legislators, and, in writing this introduction, it is in the hope that this publication may serve to throw light upon it, and to materially assist in its better consideration.

W. E. WEARNE,
Minister for Forests.

CHAPTER VI.
STICK INSECTS, MOTHS, SAWFLIES, AND HOMORTEROUS INSECTS ATTACKING EUCALYPTUS.

The Gregarious Phasma or “Ringbarker”
(Podacanthus wilkinsoni, Macleay).

The leaf or stick insects are well represented in Australia by many large and handsome species, but in most cases they are solitary and comparatively rare insects. So although they are all foliage eaters, still they cannot be called pests.

In this species we bave a phasmid that ranges over a considerable area of our northern coast forest lands, while odd specimens have been found as far west as the Jenolan Caves in the Blue Mountains.

They appear at irregular intervals in such countless millions, either walking or flying through the forests, that every leaf is stripped off the gum trees in their path. In 1891 Olliff stated (Agricultural Gazette of New South Wales) that the infested area was about 50 miles long, comprising a strip of thick forest including what is known as Murphy's Creek near Walcha, through the scrub to Upper Tia and Nowendoc Station to the “Gulf” a depression in the mountains towards the Manning River. In this district they were known as “Ringbarkers,” and “Lowrie's Flying Gang,” on account of the leaf stripped forest looking after they had passed through as if all the trees had been killed by ringbarking. The type specimens were collected by the late Mr. C. S. Wilkinson; he handed them to Sir William Macleay who described them in the Proceedings of the Linnean Society of New South Wales in 1889. Macleay commenting on Wilkinson's notes said; “It was probable that in many cases where the trees were found to be dying out, from no apparent cause, that it might be brought about by the infestation of this or other allied species of plant eating phasmids.”

In February, 1905, I visited the Nowendoc district when the whole forest was alive with these active creatures, and collected a very large series; afterwards publishing a paper in the Agricultural Gazette entitled “Stick or Leaf Insects“. Some years later I investigated the damage caused by a still larger army about 20 miles east of Glen Innes. I visited a small sawmilling plant in their direct line of march, the owner of which informed me that thousands crawling over the boiler had been scorched to death, and the engineer had to shovel them off the top of the portable engine.

The foliage of all species of eucalyptus was devoured but no other forest trees were molested; the native cherry, wattles, river oaks; and other under brush were fully foliaged among the leafless gum trees. There is no doubt that the action of the insects defoliating these trees, even at irregular intervals, is a set-back to their growth, and causes the tops to die back and form many dead branches, thus reducing the value of many valuable timber trees.

The adult females, when their bodies are distended with eggs, cannot fly; and while crawling and feeding among the foliage they drop their hard oval seed-like eggs one by one into the soil beneath. We do not know how long

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these eggs can remain fertile on the dry ground; but the egg stage may be six months or more; and for several months the tiny baby phasmids would not be noticeable among the foliage.

Probably the most effective way, where practical, of getting rid of these insects, would be to fire the underbrush and burn the eggs and young phasmids before they have moved on up into the tree tops

The adult insects are handsome creatures. The smaller male measures about 3½ inches from the front of the head to the tip of the tail, and has a wing expanse of about 4 inches. The general colour is dull green with brownish legs, the small fore wings edged with white on the outer edge. The large hind wings are pink shaded with purple, striped on the front margin with green and oraimge yellow at the base. The larger and more bulky female differs from the male in having the hind wings a deep rich purple colour.

The members of the family Phasmidæ have no means of protection against their many enemies, except that of exuding a drop of offensive smelling fluid from the mouth which may be objectionable to predaceous insects and birds. Their structural peculiarities and colouration are so adapted to their surroundings, that, until they move, they are very difficult to find. This is known to naturalists as protective mimicry.