MAY. 107 



great depth in the earth, and come within an inch of the 

 surface ; when full-grown they again retire to the depth of 

 two feet, where they become pupae, having before con- 

 structed a cell, of an oval form, and very smooth in the 

 inside. They assume the perfect state in February, but do 

 not venture into the air until the fine days of May ; their 

 existence is then but short ; remaining inactive during the 

 day, they only emerge from their retreats at sunset, and fly 

 humming round the trees. In favourable seasons they 

 swarm to a great extent, and the damage committed by 

 them is often serious. Mouffet informs us that in 1574 so 

 great a number of these insects were driven into the Severn, 

 that they hindered the mills from working, and it required 

 the united efforts of hawks, ducks, and people to destroy 

 them. Some districts in Ireland were completely devastated 

 by them many years since ; they were first seen in Galway, 

 hanging from the trees in clusters, dispersing at sunset 

 " with a strange humming sound like the beating of drums, 

 and darkening the air for the space of two or three miles 

 square ; in a short time they entirely ate up all the leaves, 

 stripping the trees as bare as in the depth of winter : the 

 multitude spread so much that they infested the houses, and 

 became extremely troublesome. Happily, high winds and 



