COMMON TREES IN EELATTON TO AERIAL LIFE OF BEETLES. 43 



Icafag'e it yields splendid slielter for the beetles during the day. Girault 

 and Dodd gave the River Cherry (Eugenia tierneyana) , Leichhardt-tree 

 {Sarcocephalus cordatus), and the Cockatoo Apple {Careya australis) 

 as being occasionally attacked, but in our experience they can only be 

 classed as harbouring trees. The BainboO' is often regarded as an 

 important food plant; we are mindful of clumps of these in canefields, 

 -where the beetles swarmed in vast numbers each night, and yet 

 investigation failed to show that the foliage had in any way been eaten. 



The third and fourth classes in the list are interesting in view of 

 the fact that they show what common trees may be planted or let groAV 

 around homesteads, canefiekls, (fcc, with a reasonable degree of impunity. 

 'Of course, it is quite feasible that, with the absence of the usual feeding- 

 trees, the beetles will turn their attention to those that are now con- 

 sidered immune. One that we can commend highly as an ornamental 

 and shade tree is the River Cherry (Eugenia tierneyana) ; the glossy 

 green foliage is very distinctive and gives splendid shade, and the 

 jn-olitic crops of cherry-like fruit can l)e used for making very good jam. 



Perhaps the most interesting feature in a study of the feeding-trees 

 is the obvious discrimination in the choice of food that the beetles exhibit, 

 even between trees that are closely related. A striking example of this 

 power of discernment is observed in the Wattles ; among others, two 

 species occur in great profusion in the Cairns district — namely, the 

 Black Wattle (Acacia aulacocarpa) and the Cream-flowered Wattle (A. 

 JIavescens) ; the former has not under any circumstances been recorded 

 as being eaten, while the latter is one of the most important feeding- 

 trees. A yet more forcible case is instanced in the various forms of the 

 Paper-barked Tea-tree (Melaleuca leucadendron) , one variety of which 

 is highly favoured by the beetles, the other three apparently being 

 immune. Six members of the genus Eucalypius thrive in the neigh- 

 bourhood of Gordonvale ; one, the Moreton Bay Ash, is more readily 

 attacked than any other tree ; four are more or less preferred ; and one, 

 the Poplar Gum (E. platyphylla), is palpably distasteful. In this family 

 (^lyrtaceffi) there are two exceedingly common trees in this same district, 

 the Swamp ^lahogany (Tristania suaveolens) and Cockatoo Apple 

 (Careya australis) ; both of these are everywhere to be noticed in the 

 forest areas, but neither suffers invasion. Then, too, in the genus 

 Glocliidion, one species is much fancied, the other, to our knowledge, not 

 being appreciated (of this second species, G. lohocarpus, Tryon records 

 that "it is also attacked by the beetles," although we have not found 

 such to be the case). Finally there are the various Figs; no dis- 

 crimination seemingly is made between the several Strangle Figs; the 

 rough-leaved variety (F. opposifa) is eaten intermittently, but some 

 of the smaller kinds that are rarely more than shrubs, as F. mag lu folia, 

 F. casearia, and F. Jdspida,. would seem to escape aggression. 



The knowledge that cane-leaves are sometimes eaten leads to the 

 interesting surmise that if the forests were cleared away it might be 

 possible for the beetles to sulisist entirely on this foliage. However, 

 ■considering the myriads that breed in canefields and the immense number 

 of females that return to deposit their eggs, it is not surpi'ising that a 

 few individuals have accjuired the habit of dawdling there for a day 

 or so to eat; it has been found that these stragglers were invariably 

 newly emerged, or females re-emerging from the ground after egg-laying. 



We are indelited to jMr. C. T. White, Government Botanist, for the 

 determination of the i)lants in the above list. 



