50 AUSTRALIAN SUGAR-CANE BEETLES AND THEIR ALLIES. 



I came upon the third set about 5 inches further in and 10 inches 

 deep. Only nine eggs could be found; these were right down in the 

 hard yellow-clay subsoil. A little further, and about 8 inches to one 

 side, were eight more eggs, at a depth of al30ut 7 inches. And, finally, 

 there was a cluster of six eggs near the far edge of the cage, at a depth 

 of 9 inches, thus making a total of thirty-eight eggs found. 



Evidently we did not get all of them, for both females Avere found 

 in the soil, and on dissection showed that they had completed laying. 

 There is, hoAvever, the possibility that one of the beetles had laid before 

 she was placed in the cage. The only male found was at a depth of 



4 inches, which is very similar to our other observations on their hiding 

 during the day. 



10th January, 1921, I found eggs of this species under natural 

 conditions in grass land. They were scattered in an area of a few- 

 inches, about 10 inches below the surface. Each egg, as usual, was 

 enclosed in a tiny cell. This chamber is evidently made by the protruded 

 portion of the vagina, which has chitinised spots protecting the cement 

 glands. Furthermore, in some of the cells there is an evident opening 

 on one side, through Avhich the egg was laid. The compacting of the 

 soil in forming the chamber naturally results in the particles clinging ; 

 hence the nodule effect around each egg. The chamber makes provision 

 for the swelling of the egg as the embryo develops (Plate XIV). 



I nuist noAV briefly refer to the peculiar behaviour of beetles confined 

 in soil without access to eJther food or light. Three females taken whilst 

 mating, 1st December, 1920. were used in this experiment. The three 

 remained alive until 13th January, 1921 ; they appeared to behave as 

 unemerged adults, and the absence of light seems to have had the effect 

 of making them hibernate. 15th January, one was found dead ; it had 

 lived 43 days, and the body was full of ripe eggs. On 24th January, 

 another died ; this lived 53 days and was full of ripe eggs when dissected. 



On 31st January, the last beetle was found in the act of ovipositing ; 



5 eggs were l.ving loose in the soil. Next day, 19 more eggs had been 

 laid. On 2nd February the beetle was dead ; on dissection 12 more ripe 

 eggs were found in the ovaries; thus, counting all of these, she had a 

 total of 36 eggs. Instinct had evidently caused it to deposit its eggs, or 

 as many as possible, before succumbing. It lived 62 days without food 

 or light. 



Thus though the lieetles remained apparently semi-torpid ou account 

 of the absence of light and food, and the development of the eggs was 

 suspended, or at least deposition of them, they were eventually laid, 

 which shows that food is not at all essential. 



Again, in nature the species copulates repeatedly; this does not 

 seem necessary, and the reason is not apparent, since this one could 

 deposit her eggs 60 days after copulation. The eggs were fertile and 

 hatched subsequently. 



Duration of the Egg Stage. — 22nd January, eggs dug out of the soil 

 under the garden cage on the 8th, and probably laid on the 7th, hatched, 

 giving a length of the stage as just 16 da.ys. Numerous other records 

 showed that this time was not nuich out of the way, though in a few 

 cases a slightly longer period was required. 



In all cases the eggs were kept in soil in small tins on the shelf of 

 the insectary, and the soil kept moist. The temperature of the soil here 

 would no doubt be several degrees less than under natural conditions. 



