308 Journal of Agriculture, Victoria. [10 Mat, 1917. 



TWO DESTRUCTIVE INSECT PESTS OF PLANE AND 

 ELM TREES IN VICTORIA. 



By C. French, Jun., Gorcniment Entomologist. 



In addition to fungus diseases, many of the elm and plane trees 

 growing in tlie public parks, gardens, and streets are affected with insect 

 pests, one of the worst being the " Cherry Borer Moth " (Maroga gigan- 

 iella, or sometimes called Vryptophasa ntiipunctata). 



The caterpillar bores within the limbs of plane and elm trees, and 

 protects the outside of its tunnel with a covering of web, gnawed bark 

 and droppings. If numerous, the trees are seriously injured. The 

 caterpillar is a pinkish-white insect, hairy, with a black head, and, when 

 full grown, about 2 inches in length. The perfect insect is white, 

 shining, front of head and antennae black ; forewings, in some instances, 

 more or less greyish, the whole wings having a somewhat silky appear- 

 ance with a black spot on each; liind wings darker. The moth is about 

 the size of the well-known vine moth Phalaenoides (Agnrista) glycine. 



The larva> of this moth destroy the trees by first tunnelling for some 

 distance under the bark, and then gnawing their way right into the very 

 heart of the tree. The sawdust-like excrescence on the trees being quite 

 sufficient indication of the presence of borers in general, and this one 

 in particular. 



Prevention and Ivemedies. 



Clear away the sawdust-like matter, the removal of which will indi- 

 cate the direction taken by the grub. Kemove as much of this material 

 from tlie tunnel as possible, then soak a piece of rag or wadding in 

 carbolic acid, plug this into it and close over with clay or soap. Another 

 plan which is adopted is to probe the tunnel with a piece of strong wire, 

 and in this way the grubs are often reached and destroyed. Sjiraying 

 the trees with tar-impregnated water is also beneficial. The formula 

 for coal-tar water is as follows : — Boil 1 lb. of coal-tar in 2 gallons of 

 water, and \Vhile hot add from 50 to 100 gallons of water. Strain well 

 before using. 



The larvas of the "Painted Apple Moth'' {Teia anartoides) is 

 becoming a serious pest to plane, elm, and other street trees. This 

 insect formerly fed on the leaves of various acacias (wattles), but like 

 many of' our native insects has attacked other trees, causing much 

 damage to same. The caterpillars of this moth usually eat the young 

 foliage of the trees. The female moth is a short-rounded creature 

 destitute of wings. Her life-work is very limited, as she simply crawls 

 out of her shelter, lays her eggs on top of it, and then dies. The male 

 moth has brownish upper wings with three whitish dots on each wing; 

 underwings, the upper portion yellow, the lower portion black or dark- 

 brown. The caterpillars are brownish, and are thickly clothed Avitb 

 long hairs, with two singular reddish-coloured appendages projecting 

 from the back near the tail. 



Remedy. 

 Spray trees Avith arsenate of lead, 1 lb. to 25 gallons of water. 



