306 FOREST ENTOMOLOGY. 



is Ohaitophorus aceris or " hairy aphis." It is common in many 

 districts, but I first discovered it in Sherwood Forest on May 25, 

 1896. 



The general difference is that this species is more hairy, and is 

 altogether smaller. The antennae, legs, wings, and cornicles are all 

 respectively shorter. The abdomen is studded over with tubercles, and 

 each tubercle is surmounted by a tuft of bristles. The legs are com- 

 paratively short, and the wings are veined as in Aphis. 



There is a unique interest attached to this species on account of 

 its special dimorphic forms. Its peculiar and interesting life-history 

 may be briefly told. During the winter months the apterous oviparous 

 female, which is the foundress of next year's broods of insects, may 

 be found in the crevices of the bark, together with the dark shining 

 eggs she had deposited in the crevices of the bark. From those eggs, 

 which hatch in spring, we get the apterous viviparous females, which 

 are comparatively small, of a greenish colour, and produce light- 

 yellowish or darkish larvae. The latter are rather variable in detailed 

 colour. 



The pupae are smaller than the apterous viviparous females, and 

 have rather lightish-coloured legs and dark-coloured wing-cases. 



Arising from this brood there are two varieties of winged viviparous 

 females. The first variety to be considered is one with black head 

 and thorax and greenish abdomen, which is ornamented with a few 

 cross-bars. The cornicles are small and black, and the whole insect 

 more or less hairy. The second variety is rather larger than the first, 

 with comparatively larger wings, and the creature is more pilose than 

 the former variety. 



It is, however, with regard to the young produced by those two 

 varieties of female insects that the chief interest is attached. The 

 first variety produces normal insects, which in turn give birth to other 

 insects, and so on throughout the summer season. The second variety 

 produces a class of insects so distinct, and differing so much from all 

 other Aphididae, that it has not only received several synonyms, but a 

 suggestion has been made to relegate this variety to a separate family, 

 between Coccidae and Aphididae. I found several specimens on the 

 common sycamore in Sherwood Forest, and tried to induce them to 

 live in Cheshire, but without success. They are born in the early part of 

 summer, and live until autumn, never moving from their early habitat 

 or respective leaves, and, with the exception of moulting, undergoing 



