PRESIDENT'S ADDRESS. Ixi. 



width of about four feet, and its usual habitat is the seas to 

 the N. of Africa. The account of the habits of a fish-eating 

 spider (Thalassius spenceri, P.-Cambr.) from Natal, is new 

 to me and interesting. The body is small with long legs, 

 and when in quest of prey, it places its two hind legs on a 

 stone and the other six on the water, watching for fish. When 

 a small one comes within reach, it plunges head and legs 

 beneath the surface, holds the fish with its legs and pierces it 

 with its poisonous fangs. It then retires to land and eats it. 

 The second Entomological Congress was held in 1912 at 

 Oxford, and brought together Entomologists from many parts 

 of the world with many interesting papers, amongst which I 

 may mention one by our member, Sir Daniel Morris, dealing 

 amongst other things with the method of reducing insect 

 pests by introducing their natural enemies, parasitic or 

 otherwise. A valuable collection of Foreign Lepidoptera, 

 containing about 150,000 specimens, has been left to the 

 nation, enriching the large collections already contained in 

 the Nat. Hist. Museum. In the theory of Mimicry in 

 Butterflies, a great deal naturally depends upon the assumed 

 fact that they are much used as food by birds, but the catching 

 or even pursuit of a butterfly by a bird is an incident not 

 often witnessed, and the observation of the proceedings of a 

 wag-tail, which in 25 minutes caught and ate about 23 

 butterflies which had settled on the damp sand by a stream 

 in E. Africa, is, I should think, almost unique. The bird 

 rejected one butterfly, an Acrcea, as unpalatable. Experi- 

 ments in Canada shew the response made by the females of 

 luminous insects to a flash by the male when flying above 

 her, possibly this occurs in the English glow-worm. Everyone 

 must have noticed the dead flies which sometimes stick to 

 the windowpanes and elsewhere, covered with a white mould. 

 Attempts have lately been made to cultivate this fungus 

 with a view to the destruction of flies, but though the cultiva- 

 tion has been successful, there may be difficulties in applying 

 it to the fly, which takes the infection by eating the spores. 

 Stomoxys, the biting fly, very like the common housefly but 



