16 THE WONDER OF LIFE 



lurk like the crocodiles, some act burglar like the ant-eater 

 bursting into the termitary, some hunt in packs and some 

 alone, some utilize what others have won. Thus in the 

 North of Scotland it is not an uncommon sight to see a 

 Skua gull (Stercorarius) chivying herring gulls in the air 

 until they disgorge their last caught fish. It is an astonish- 

 ing fact that this should be sometimes re-caught by the 

 skua before it reaches the water. What a long gamut 

 there is between the behaviour of these skuas and the land 

 leeches in the tropical forest ! ' Only too frequently ', says 

 M. Coupin, ' one hears a sudden noise like hail falling on the 

 branches. It is not falling hail, but leeches, which hasten 

 to attach themselves to beasts of burden and to men, from 

 whom they proceed to suck the blood. They were watching 

 [sic] their chance, perched on the branches an odd 

 dwelling-place, by the way, for creatures that are generally 

 considered aquatic '. 



We have referred in " The Biology of the Seasons " to 

 Jacobson's extraordinary story of a mosquito milking an 

 ant. For that is what it comes to. The mosquito frequents 

 certain trees in Java on which the ants (Cremastogaster 

 diformis) go to and fro. It hails a passing ant and strokes 

 her head with quick movements of fore-legs and antenna. 

 Perhaps it tickles, perhaps it massages the ant who can 

 tell ? It seems to please her anyhow, for she emits a drop 

 of juice which the mosquito sucks up. The mosquito 

 has been named Harpagomyia splendens by de Meijere, 

 who points out that the creature cannot bite. But to 

 beg it is not ashamed. Jacobson found two other 

 Dipterous insects in Java which seem also to have learned 

 how to tap ants. These extraordinary inter-relations 

 recall the well-known but very remarkable fact that 



