4 INSECT ARTIZANS AND THEIR WORK 



animated particle to feed in safety, no matter how 

 violent the jerking of the leaf from side to side. 



Another simple, but highly useful, example of 

 the spinning power is exhibited by leaf-rolling 

 caterpillars (Tortrix) and the elongated caterpillars 

 known as Geometers from their peculiar manner 

 of progression, in which they appear to be care- 

 fully measuring the distance traversed. Some 

 caterpillars of these two families, when the bough 

 upon which they are feeding is rudely jerked, at 

 once loose their hold and simultaneously spin a 

 single thread by which they hang suspended in 

 mid-air until the supposed danger has passed, when 

 they ascend the thread and regain their former 

 station. 



These same leaf-rollers depend largely upon their 

 power of spinning threads for the skill with which 

 they accomplish the neat leafy tube which is at once 

 a house and a dining-table. If we walk, in May 

 or June, through an oak wood, we shall see a number 

 of these caterpillars hanging by silken threads 

 which are only made visible to our sight by their 

 reflecting the sun's rays. Tracing one of these 

 gleaming threads upward, we shall see that it 

 depends from the open end of an oak leaf that has 

 been rolled into a tube, and if we wait a few minutes 

 we shall see the wriggling larva after climbing up 

 by its thread disappear into the green tunnel. 

 Plucking a rolled leaf, we find that the coils are 

 held in position by a great number of threads which 

 stretch like tent-ropes from the curved to the 



