From Ferdinand von Mueller to Alfred Douglass   [June 1885]

I am well aware of the danger of elms being lost through boring insects, and that thus whole shade lines of fully up-grown trees may become destroyed, as European sad experience on this subject has repeatedly proved. Indeed, more than twenty-eight years ago, when I commenced to plant the first shade lines of trees in Victoria, I bore these facts well in mind, and had on this subject a correspondence with the late Mr. Edward Wilson,¹ who was then in England, and took great interest in tree-planting also, while aiding with Mr. YouI so prominently in Australian pisciculture. About that time also there was much loss among elms in England. There, as in many other parts of Europe, the larvae of the 'goat moth' (Cassus liguiperdo)² and a small beetle (Scolytus destructor) are the main borers of the elm, which not rarely succumbs to their ravages. One remedy would be the encouragement of wood-pecking birds to increase here, by letting our few native species alone and unmolested, and by introducing the best kinds of foreign birds of this sort; the 'shanghai'³ and the reckless use of the sporting gun to be suppressed by police vigilance, bird-protecting clubs, and heavy fines anywhere. In France, trees commencing to suffer from the goat moth are (on the original recommendation of the great entomologist, Latreille), surrounded at the stem base with a mixture of clay and cowdung, by which means the larva of the cassus, which are hatched from eggs deposited at the bottom of the stem, are prevented from penetrating the stem. Whether any similar means are of avail, to prevent the large grubs of the eucalyptus moth, endoxyla eucalypti (which bores not only the stems of our blue-gum trees, but also that of some other eucalypts and of our wattle), from getting access to elms, requires to be ascertained. Trees of healthy growth in well-adapted soil would be far less liable to the boring of the endoxyla than sickly trees, planted in more or less unsuitable soil and subject to stagnant moisture at their roots. Lingering blue-gum tees, when bored by the endoxyla, I have often saved by starting them again into vigorous growth through surrounding the base of the stem with an earth seat, covered with sods of Indian couch-grass, it being also necessary under any circumstances to remove old and loose pieces of the outer bark regularly from the stem, to prevent insects from harbouring under such shelter. As the attack on your elms seems a new one here, it would be necessary to initiate experiments as to the best means of protecting these English trees under altered circumstances in this colony. I should like to see a sample of the larva, pupa, and perfect insect destroying your elms there. Some kinds of our eucalyptus are also attacked by beetles, as borers into the wood, the two most formidable, as identified by Mr. French,⁴ being Hapatesus nirtus⁵ and Phoracantha nicusyus,⁶ particularly the latter. The discussion of this subject brings me back to my original recommendations, made more than thirty years ago to adopt for street lines only such trees as are known not to be readily subject to diseases, whether arising from insects or from fungi or otherwise. Thus many pines are also exempt from parasitic attacks. The native red-gum tree (E. rootrata⁷), with its antiseptic wood, is also far preferable to many other eucalyptus for lasting avenues, and many other trees deserve consideration, concerning which my inexpensive work on 'Select plants for Industrial culture and naturalisation'⁸ might be consulted, which is obtainable at the Government printing office in Melbourne, and of which an enlarged edition, by the approval of the Hon. Graham Berry, will appear towards the end of this year.⁹

P.S — It might be tried to give the affected portions of the stems of your elms a coating of coal-tar.¹⁰

Eucalyptus rootrata