88 
THE STUD Y OF INSECTS. 
short distance it alights and sheds its skin again, a thin layer 
coming off from all parts of its body, even from its wings. 
After this the delicate creature is more fragile than before. 
It now has but one duty to perform in its brief life in the 
air, and that is to lay its eggs. These are sometimes laid 
on the surface of the water, and sometimes the mother wraps 
her wings about her like a diving-bell and goes down into 
the water and deposits her eggs on stones. The life of the 
nymph is from one to three years, according to the species. 
