108 LONDON INSECTS 



One of the many things which naturalists have yet 

 to learn is the explanation of the appearance of 

 thousands of the same fly at almost the same moment. 

 Not a May-fly is to be seen for months, and then, no 

 one can tell why, all at once the trout are leaping at 

 them in every direction. 



This is even more remarkable on some of the 

 German rivers, where on a warm evening swarms of a 

 large, light-coloured Ephemera come out suddenly, till 

 they look like a thick mist on the water. Straw fires 

 are lit on the banks, and next morning basketfuls 

 of yellow-bodied flies, with white wings singed, are 

 swept up for the poultry. Why is it, too, that probably 

 within five minutes of one another, all the Bats in a 

 neighbourhood wake and come out ? 



The habit is to be noticed in London as well as 

 anywhere. There was until a year or two ago at least 

 one tree in Kensington Gardens an old hollow oak, 

 between the refreshment-room and the gardener's 

 cottage the home of a considerable colony of Bats. A 

 note was made of the exact hour at which the long 

 silent procession left the hole one evening in August. 

 The next day, within four minutes of the same time 

 the time was carefully taken seventeen Bats crawled 

 up, and with the same regular intervals took headers 

 into the dusk, to appear again as if they had started from 

 another quarter altogether, careering about over the 

 tops of the trees, doing the best they could to prevent 

 too great an increase of humbler London night fliers. 



The part which insects and kindred small creatures 



