132 BRITISH APHIDES. 



When full-grown; globular, very sliiniug dark green, 

 or nearly black after removal from the gall and expo- 

 sure to the air. Antennae very short and only four- 

 jointed. Body furnished with a few fine hairs, lout not 

 clothed with any abundance of cottony fibre. Eyes 

 small and black. Legs short. 



Notwithstanding some risk of recapitulation (since 

 the life-history of Tetraneura has much in common 

 with that of Pemphigus), I append my own observa- 

 tions on this species, which accord with those of Dr. 

 H. Kessler, of Cassel, and the American naturahsts. 



Early in the spring, minute, longish, black, shining, 

 un winged insects may be found close to the leaf-buds 

 of onr elms. They are about O'OIO of a milhmetre 

 long. These are the Queens of the colonies which are 

 to appear through the year. 



As soon as the young leaves unfold, these insects 

 commence their irritating actiou, and the leaves then 

 show, by the red spots on their under sides, that there 

 is a diversion of the sap, causing a cupping of the 

 edges of the rising blister, which finally arches over 

 and encloses the growing Aphis. 



So far as my observations go, the leaf is attacked 

 not only at the midrib, but also in the spaces between 

 the other leaf-veins. In all cases, however, the gall 

 becomes pedunculated, and rises a considerable dis- 

 tance above the surface. 



The size of these galls would seem very much to 

 depend on the season and the luxuriance of growth of 

 the trees. German specimens* are described as either 

 round or of an oval form, the long diameter being 

 about one centimetre ; but I have certainly in England 

 seen them larger than three eighths of an inch. 



In the neighbourhood of Cassel they are described 

 as studding the trees occasionally in such masses, that 

 they bow down the points of the branches. 



* For more minute particulars the reader is referred to Dr. Kessler's 

 'Die Lebeusgescliiclite der auf Ulmus campestris vorkommeuden 

 Apbiden-Arten,' &c., and M. L. Ooui'cliet's ' Etude sur les Galles pro- 

 duits par les Aphidiens/ 1879, 



