76 BRITISH APHIDES. 



brane. All tlie nervures themselves are dark brown. 

 The lower wings are unclouded. 



This pretty insect is one of the largest of the family 

 of Aphis, and is diffused over a large area of the Old 

 World. It was found by Dr. Rosenhaur inhabiting 

 the oaks of Croatia, whence its name. It is also found 

 far north in Sweden, and has been discovered in Central 

 Asia in the district of the Amur (Walker). As it 

 does not appear in Passerini's list, perhaps it is con- 

 fined to the cold and the more temperate regions of 

 the south. 



This insect is not uncommon in several parts of 

 England. The examples figured w^ere kindly sent to 

 me by the Rev. N. Andrews. He obtained them by 

 climbing the branches of an oak at Southwater, 

 near Horsham. They are usually stated to prefer the 

 branches springing from old oak stumps. The ants 

 Formica ruhra and F. fuUginosa seem greatly to relish 

 the juice excreted from their nectaries. Late in Novem- 

 ber I received a consignment of these Aphides from 

 Montpellier, and also a leaf of the evergreen oak Quercus 

 ilex, on the upper surface of which some hundreds of 

 dark brown eggs had been deposited, — the produce of 

 several females, five of whose dead bodies were still 

 attached to the patch of ova. 



The eggs, which are not strictly oval in form, but 

 inflected on one side, were laid very closely together, 

 mostly in parallel rows. They were covered with a 

 glutinous substance which was insoluble in water, for 

 they could not be detached by a camel-hair brush 

 filled with water. This covering seems to con- 

 tinue moist, since it entangles particles of foreign 

 matter which float in the air, and thus perhaps an 

 artificial protective coat is formed. M. Lichtenstein 

 notices these diff'erent locations of the ova in D. rohoris 

 and D. Groaticii>s, and considers the circumstance as 

 confirmatory evidence of the insects being specifically 

 different. 



From specimens mounted by Mr. Walker — I beHeve 



