Schizoneura ulmi. 



These rolled, distorted, and swollen leaves are due to the 

 combined attacks of the queen, the larvae she gives birth to, and 

 the nymphs resulting therefrom. Emerging from an egg laid 

 in the bark of the tree in the previous autumn, or from the dead 

 body of her mother in which the egg had remained during the 

 winter, the foundress of the colony attacks the underside of 

 a leaf soon after it has unfolded, and by puncturing and sucking 

 the sap causes it to blister outwards and form numerous 

 cavities, which are partially divided from each other by the 

 lateral veins. The affected half of the blade of the leaf curls 

 downwards and under, forming an uneven but gracefully shaped 

 roll. The exterior turns from green ,to pale green, later on to 

 a yellowish green, and finally to a pale ashy grey. Within the 

 distorted portion of the leaf the queen gives birth to a large 

 number of young, enveloped within a semi-transparent mem- 

 brane, which, however, is soon cast off, and for a brief time they 

 are like larvae. Changing ultimately into nymphs, they finally 

 emerge as alate imagines, which fly to other leaves and start new 

 colonies. Four other generations are necessary with this species 

 before reverting to the queen aphis. Elm leaves may occa- 

 sionally be found where the blade has rolled upwards and along 

 the upper surface. They appear to be the work of the same 

 species. The interior of the roll is usually filled with flocculent 

 matter, the exuviae of the larvae, and the puparia of the nymphs, 

 and also minute globular, yellowish drops of moisture. 



The illustration is of specimens gathered at Hastings by 

 the author. 



246 



