70 AUSTEALIAN SUGAR-CANE BEETLES AND THEIR ALLIES. 



of 34 grubs collected on Sth Fehruary, 1921, 9 were in stage II ; eight 

 of these were kept to ascertain their growth ; five were still in stage II 

 on 23rd February, and the last to moult did so early in April. Dodd 

 (91) has listed stage II larvae in the field as late as 16th April. How- 

 ever, this is unusual ; as a matter of fact, it is very rarely that this 

 stage is met with after the end of February in a normal year. 



As the grubs often attain stage III very early, so their maximum 

 growth may be achieved exceptionally quickly, when they finish feeding 

 and go into cells preparatory to pupating. These fully fed individuals 

 have a characteristic appearance, being of an opaque yellow tint, the last 

 segment of the abdomen showing semi-transparent ; their bodies contain 

 nothing but fat. Twenty-five healthy stage III grubs were collected at 

 Greenhills on 9th February, and retained in pots of soil at the labora- 

 tory; one of these was already yellow and in a cell on 23rd February, 

 and the majority went into hibernating quarters during jMarch and 

 April. Again, of eight normal stage III taken in a refuse heap of 

 ■decaying vegetation on 19th February, five were in cells on 9th IMarch. 

 Therefore, their active feeding period in the grub stage endures for only 

 a few weeks, and the greater part of their pre-adult life is spent in 

 hibernation. When in this condition, however, they are not passive ; 

 emptied out of their cages and the cells l)roken up, they cjuickly dig in 

 again, and when next examined will have again constructed their 

 quarters. 



It was thought that perhaps these yellow specimens might be para- 

 sitized; several were dissected without finding any trace of parasitic 

 larvffi. Yet those that remain over after the normal time of pupating 

 liave commonly been discovered to contain dipterous maggots. One of 

 these yellow grubs, unearthed at Greenhills on 25th January, 1921. wag 

 dead on 3rd February, with a large maggot in its body. 



Out of the soil the grub is very active, and, moving on its venter, 

 its rate of locomotion is much faster than that of AnopJognaihus and 

 similar species that travel in this way. 



The Pupa. — Our notes contain no references to the pupal stage ni 

 the field. However, at Greenhills on 3rd August, 1920, digging a trench 

 under cane-stools gave one larva in its pupating cell at a depth of 18 

 inches, and three in cells at 24 inches. Another trench yielded four in 

 cells at 12 inches, and six at 18 inches; none were deeper, though the 

 trench was excavated to a de]ith of 36 inches. 



CACACHROA DECORTICATA MACLEAY. 



This day-fiying species is of interest chiefly on account of its 

 divergence in the larval state from the general lial)it of the Cetonida? of 

 living in decaying wood ; its grubs are very plentiful in the soil at the 

 hase of blady grass {Imperata arimdinacea) and other native grasses. 

 Girault and Dodd (66) devoted considerable time to the study of this 

 species, and as we have little subsequent data Me have not recapitulated 

 their notes on the life-history. However, it certainly seems that the 

 adults have not been so numerous latterly as in 1912-14. In the 1919-20 

 season a few were first observed flying low over the ground in the forest 

 and edge of canefields on 16th January, and up to the end of that month 

 they were captured sparsely on flowers of swamp mahogany {Tristania 

 suaveolens) and cork-tree {Evodia accedcns). Again, in the past season 

 large numl^ers were not observed ; on 31st December, they were plentiful 

 ■on a flowering river cherry {Eugenia tiermyana) . 



