38 ANIMAL ARTISANS 



animals make a half-burrow or open excavation 

 the former by biting the lower stems and roots of 

 the rough grasses away, and the latter by tunnelling 

 with their backs level with the surface. These open 

 trenches, as the vegetation wears away from above, 

 are occupied by big spiders, which cover the bottom 

 with curving sheets of web woven close like silk. At 

 the end, perhaps four or five inches from the beginning 

 of the trap, they form a continuous, funnel-shaped 

 arch of web, in which they lie hidden. Grains of 

 earth and seeds of grasses fall on to the open trap, 

 which looks like a nice even little road, leading to a 

 hole. Insects of many kinds see this smooth, groove- 

 like path, and attempting to run along it, are en- 

 tangled, and then pounced upon by the spider. Even 

 a mouse is embarrassed if it is frightened into one 

 of these trammel-roads hung with " toils " of web. 



Great numbers of industrial insects make paths for 

 use on expeditions which involve the transport of all 

 kinds of loads. But it would be difficult to name 

 a single instance in which they consciously improve 

 the road to facilitate traffic. The roofed paths of 

 many African ants are not rationally designed for 

 this purpose. The roof is mainly intended to keep 

 off the sun, and to enable the creatures to work in 

 the darkness or twilight, which seems a necessary 

 condition for their activities. It has also a secondary 

 and important use in protecting them from the attacks 

 of birds. But ants in general are bad engineers in the 

 road-making department. They do not clear away 

 obstacles, but climb over or round them, and though 



