London Insects. 163 



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 baskets 

 full 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 is at least one tree in Kensington 

 Gardens an old hollow oak between the refresh- 

 ment room and the gardener's cottage which is 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 

 of the kind have played and still play in the creation 

 and support of the world as we now live in it has 

 been a theme for many pleasant writers. Whole 

 island groups, described by sailors who have seen 

 them as heavens on earth, owe their beginnings to 



