14 AUSTBALIAX SUGAK-CANE BEETLES AND THEIR ALLIES. 



That the beetles flourish in wild grass land is evidenced by Stoektoo 

 paddock, near Innisfail. This grass area of 2-40 acres is a most interesting 

 ^pot, since most of the money from their Cane Pest Destruction Fund is 

 spent for beetles collected there. Furthermore, strange to say, the 

 surrounding canefields have not suffered from grub injury. While the 

 Avriter was there in June, 1919, it was easily clemonstrated by digging 

 that grubs were almndant in this grass land ; hence it woukl appear 

 that that great mass of beetles was developed right here, year after year, 

 alongside of the cultivated cane areas, without injuring that crop. 

 Moreover, digging almost anywhere in grass land, at the proper season, 

 especially where there is much of the so-called blady grass, discloses the 

 grubs, even when far removed from cane areas ; in fact, I have been told 

 that they are al)undant during their flight even up on the Atherton 

 Tableland. Then, too, we now know that these beetles have an extensive 

 range both up and down the coast; and they certainly are by no means, 

 limited to those sections that produce sugar-cane. 



Since grubs under natural conditions in uncultivated areas are 

 seldom injurious to grasses, it would appear that man, by his serious, 

 interference with the balance of nature, is mainly responsiljle for much 

 of the devastation that is now resulting to his crop. This opeiis up an 

 important sul;)ject, which will be treated in detail in a later section. 



Emergence of Beetles. 



The beetles appear any time from October to February, depending 

 entirely upon meteorological conditions. In fact they are frecpientlv 

 ready for months, waiting in their pupation chambers several feet below^ 

 the surface for the soil to become sutflciently moist for them to escape. 

 Thus, on 4th -July, 1917, the writer found beetles fully 3 feet below the 

 surface, in red volcanic soil so dry and hard that tliere was no hope of 

 their escape under such conditions. That year the penetrating rains set 

 in at the end of October, and the beetles came out in great numbers on 

 4th November. Hence the wait in the mature stage, without food, was. 

 just four months in this instance. And again, on 5th July, 1918, Girault 

 found similar conditions at Greenhills ; that year the beetles did not 

 emerge until 25th November. 



After close observations for several years, it has been our experience 

 that the beetles never appear in noticeable numbers until a few days 

 after the first soaking rains, occurring any time between October and 

 February. For instance, in the humid belts, such as the Babinda area, 

 the beetles emerge fully a month before they do in the drier sections of 

 the Cairns district. And, again, an extremely late emergence was that 

 at Meringa during the season 1919-20; the rains did not begin until 

 !15th January, 1920, and the beetles were not out in force until the 23rd 

 of that month. 



Just after emergence the exit-holes of the beetles are very noticeable 

 in the badly infested fields. These are about half-an-inch in diameter, 

 and the tube is fairly clean. It is a problem what they do with the soil;, 

 the only explanation that occurs to me is that it is compressed into the- 

 surrounding walls as the beetles push their way to the surface. In 

 November, 1911, Girault traced these tubes right down to the chambers, 

 in each of which he found a cast jnipal skin. 



After emerging the beetles usually climb up on to the cane, where 

 they frequently take their first meal, as has been indicated above 



