26 



it swells up to about one and a half times its original volume, owing 

 probably to the absorption of moisture. About fourteen to sixteen 

 days after being laid, the egg hatches and a small larva appears. 

 First it is completely white, but the head and mouthparts soon 

 become darker. As soon as it has hatched the larva breaks through 

 the clay wall of the little cavity and begins to feed and to grow. 

 Then the abdomen turns to a slate colour owing to the dark food in 

 the intestinal canal. It is interesting to watch a feeding larva. 

 First it breaks ofi" a little piece from the foodmass with the powerful 

 mandibles and masticates it further with the second pair of jaws. 

 Then it swallows it. The larva eats nearly the whole mass, but 

 leaves a wall of about half a mm. thick. The duration of life of the 

 larva is still more or less a question to me, but from some indica- 

 tions I am able to make a satisfactory conclusion. I found, for 

 instance, that when the beetles were digging their nests in early 

 spring, full grown larvie could also be found. Soine of these I kept 

 alive and they pupated live weeks later. Secondly, at that time no 

 half -grown larvae could be found, and thirdly, where I found full- 

 grown larvae there was only a very slight trace of dung, and this 

 was then usually covered up with dead leaves. Out of this I drew 

 the following supposition : — 

 i. Eggs laid in spring, 

 ii. Larva hatches in about a fortnight and becomes full-fed in 



the following spring, 

 iii. It pupates about the end of July, 

 iv. The beetle is formed in the beginning of September and comes 



to the surface. 

 V. Later on it makes a vertical tube, at the bottom of which it 



hibernates and comes out again the following spring, when 



egg- laying is commenced. 

 If this be true or not further experience will have to settle. But 

 since I found no young larvae in spring it is unlikely that eggs 

 would be laid in September, because then the larvae would be half- 

 grown in spring. It follows also from this supposition that we 

 must have two races of beetles, since from egg to egg, i.e., horn the 

 time that an egg is laid till the beetle coming from this egg lays an 

 egg, there elapse two years, and the beetle would only be found 

 every other year. Some connegtion may exist between these two 

 races, as it is known from other insects which usually take two years 

 to complete their metamorphosis, that some hurry up in feeding and 

 take only one year to come to maturity. This may then perhaps be 

 sometimes the case with Geotrupen: but this is, at present, only a 

 supposition. 



The fuUgrown larva is rather sharply bent. The abdominal seg- 

 ments are much broader than the thoracic, and measure l^cn). to 

 l^cm. in the thickest part. The head is about 6mm. wide. The 

 thorax near the head is 7mm., and near the abdomen 8ium. across. 

 The whole length of the larva is about 4cm. to 4|cm. The head is 



