BEETLES 161 



in books on the natural history of insects. Less 

 familiar is Panesthia javanica, a Cockroach that swarms 

 in multitudes in decaying wood, and has fore-tibiae that 

 are considerably shortened and strongly spined, but not 

 otherwise highly modified. The fore-limb in Passalid 

 beetles is only moderately adapted for digging, but the 

 Copridce, which are ground-burrowers (although I have 

 also taken a species in decaying wood), have lost the 

 tarsus of the fore-limb, and the tibia is considerably 

 expanded. The fore-limb of the larva of Collyris 

 emarginatus has been already described (p. 158). A 

 very remarkable bug of the family Lygceidce, found in 

 rotten wood, has a fore-limb approaching that of the 

 Mole-Cricket. With all these we may compare the 

 corresponding leg of the Sand- Wasp or Fossor Bembex, 

 which does not burrow in decaying wood, but digs 

 holes in sand for her young. 



It may be pointed out that insects play a large part 

 in the production of the rich and fertile soil that 

 covers the floor of the jungle. The soil for the depth 

 of a foot or two is made up of vegetable detritus, 

 the deciduous leaves of trees contributing to it largely. 

 But occasionally storms sweep through the jungle and 

 bring down some of the older or weaker trees, espe- 

 cially those which have been attacked by the inter- 

 lacing parasites of the Ficus order. The trees in their fall 

 involve others in their ruin, and great clear spaces, with 

 fallen trees cumbering the ground, may occasionally be 

 met with in any tract of jungle. An examination of 

 these trees shows that they are in all stages of decay, 

 from comparatively sound timber to little more than 

 mere cylinders of vegetable humus. 



A newly fallen tree attracts for miles around all 



12 



