Pond-Bugs and Sea-Skaters. 



381 



are brown. The didius^ measures six inches, and is almost wholly of a beautiful 

 " moonlight " blue ; the exception being the dark-coloured margins of all the wings 

 and the brown inner border of the hind-wings. Menelaus- is similarly self coloured 

 without the dark outer border, but the inner margins of the hind-wings are brown. 

 Sulskowsky's morpho^ is comparatively small, measuring little more than four 

 inches across. It is of the pale blue suggestive of mother-o'-pearl, with brown 

 tips to the fore-wings, two 

 little tails to the hind-wings, 

 and two red dots above them. 

 On the under side it is marbled 

 with pale brown and brownish- 

 white, and has several con- 

 spicuous eye-spots. The ega'* 

 is a Colombian species, mea- 

 suring four inches and a half, 

 and is purplish-blue. 



Pond-Bugs & Sea-Skaters. 



Everybody knows the 

 slender little bugs known as 

 ditch-skaters ^ that flit over the 

 surface of fresh-water ponds 

 and ditches with the motion 

 of a racing skiff with outriggers, 

 except that it is spasmodic 

 instead of being continuous ; 

 but it is not so well known that 

 there are closely related species 

 who spend their li^'es on the 

 not always tranquil surface of 

 the ocean. The ditch-skaters 

 are remarkable for their long, 

 narrow bodies, and their long, 

 thread-like legs, which make 

 some of them look like spiders 

 skimming the surface of the 

 pond and never getting wet. 



The first pair of legs are 

 very short in comparison with 

 the second and third pairs ; and the object of the difference is to provide a pair of 

 limbs with which the skater can take hold either of a water-plant or of its prey. The 

 middle pair cover a considerable extent of water surface, and they help materially to 

 buoy up the bt)dy, and b\- their action row it along. The hinder pair do this also, but 

 thev are held in a mou- batkw ard direction and are used more for steerintr. The whole 



Photo by\ 



A Group of Pond-Bugs. 



[H. Bastin. 



Ill the centre is what wc may call the stick-Insect of the pond, though it is not 

 nlated to the stick-Insects proper, .'\bove, to the left, is the well-knowu boatman. 

 In the opposite comer is the equally connnon but flat-backed corixa. Another 

 common spt^cies is the naucoris, in the lower left-hand corner ; and opposite 

 to it is the familiar water-scorpion. 



of the Insect, 1 



egs as well as bod\', is covered with a hne \elwly down, scarcely 



Morplio didius. - M. menelaus. * M. sulsliowskyi. * M. ega. * Gerris. 



