20 FABKE'S BOOK OF INSECTS 



through baked earth or sandstone. When I examine their 

 deserted burrows I have to use my pickaxe. 



The first thing one notices is that the holes, which measure 

 nearly an inch across, have absolutely no rubbish round them. 

 There is no mound of earth thrown up outside. Most of the 

 digging insects, such as the Dorbeetles for instance, make a 

 mole-hill above their burrows. The reason for this difference 

 lies in their manner of working. The Dorbeetle begins his 

 work at the mouth of the hole, so he can heap up on the surface 

 the material he digs out : but the Cicada-grub comes up from 

 below. The last thing he does is to make the doorway, and 

 he cannot heap rubbish on a threshold that does not yet 

 exist. 



The Cicada's tunnel runs to a depth of fifteen or sixteen 

 inches. It is quite open the whole way. It ends in a rather 

 wider space, but is completely closed at the bottom. What 

 has become of the earth removed to make this tunnel ? And 

 why do not the walls crumble ? One would expect that the 

 grub, climbing up and down with his clawed legs, would make 

 landslips and block up his own house. 



Well, he behaves like a miner or a railway-engineer. The 

 miner holds up his galleries with pit-props ; the builder of 

 railways strengthens his tunnel with a casing of brickwork ; 

 the Cicada is as clever as either of them, and covers the walls 

 of his tunnel with cement. He carries a store of sticky 

 fluid hidden within him, with which to make this plaster. 

 His burrow is always built above some tiny rootlet contain- 

 ing sap, and from this root he renews his supply of 

 fluid. 



It is very important for him to be able to run up and down 

 his burrow at his ease, because, when the time comes for him 

 to find his way into the sunshine, he wants to know what 

 the weather is like outside. So he works away for weeks, 

 perhaps for months, to make a funnel with good strong 

 plastered walls, on which he can clamber. At the top he 

 leaves a layer as thick as one's finger, to protect him from the 



