72 AUSTEALIAN SUGAR-CANE BEETLES AND THEIR ALLIES. 



entrance. These holes were all traced to the ends, with the result that 

 a small scarabaeid was found which stridulated violently when handled. 

 The cane here was about 2 feet high, and was free of all extra vegeta- 

 tion. The beetles were about 4 inches down from the surface and 

 appeared to have entered the ground to no purpose, since all of them 

 were males. After dark, though raining, an occasional adult was 

 ol^served on the wing. ' ' 



A beetle captured by Mr. Jarvis, flying over a moist bed of ferns 

 in a garden on 23rd October, 1918, at Meringa, was confined, and 

 deposited 15 eggs. That observer states : — 



"The eggs are evidently deposited each one in a cavity liy itself, 

 the cavity being large enougli to allow room for the egg to expand whilst 

 maturing. The cavities particularly noticed were in each case made ni 

 small nodules of consolidated soil." 



Mr. Jarvis also established the fact that the life-cycle is not con- 

 tinued beyond a year. Larva- hatched from the above eggs during 

 November; of the 11 that remained alive on 17th February, 6 were in 

 stage II, 5 in stage III; thus they had attained stage III within three 

 months ; all were in stage III on 3rd March, and on 5th June were in 

 pupating cells ; a pupa was obtained on 29th July. 



Grubs can be secured from various situations, but they are not 

 alnnidant in the volcanic soils, being chiefly addicted to the moist, heavy, 

 dark loams. Although frequently met with, they are rarely numerous; 

 consequently they can hardly be counted a menace to sugar-cane. 



However, confined larva? readily killed cane-plants, and in the field 

 a specimen has been taken where it had bored its w^ay 6 inches up into 

 a cane-stalk. In IMarch, 1921, they were the only grul)s ploughed out 

 in fields on the Lower Burdekin, and during the same month they were 

 |)lentiful under trash in the middle of the cane-rows at Macknade. 



ISODON PUNCTICOLLIS MACLEAY. 



Like so many of the Bynastid beetles that live j^rincipally in the 

 soil, do not devour folige, and do not fly in countless swarms. Isodon 

 adults are only seen occasionally. We have obtained specimens at 

 lights from 10th October to 5th March. 



In September and October, 1920, an opportunity to accjuire infor- 

 mation on the life-history presented itself. During the former month, 

 "hills" were prepared with cowdung for planting cucumbers; the 

 manure was w'orked well into the soil, and covered with a few inches of 

 earth. Two or three weeks afterwards the manure in these places was 

 swarming with young grubs, and many Isodon adults were present, 

 some of which were dead. Soil that had been left for about a month 

 after treating in this way had grubs in all three stages, showing that 

 development must be very rapid. As many as 70 large grubs were 

 discovered in one "hill"; hence in many cases the cucumbers refused to 

 grow, their roots having been eaten clean away. There seemed no 

 doubt that the beetles were attracted by the manure ; that the grubs 

 lived on this substance and subsequently attacked any adjacent vegetable 

 matter. 



Experiments were then instituted for the purpose of determining 

 the life-history. "Hills" were prepared with manure on 23rd October, 

 and when examined on 2nd November grubs were hatching. On 25th 

 November most of these had just entered stage II, and on 17th December 



