TREES AND SHRUBS 



called Gall-gnats and Gall-midges, and the greater number of these belong 

 to the sub-genus Cecidomyia. 



Cecidomyia cratcegi causes a cluster or rosette of 8-40 deformed leaves 

 at the extremity of a shoot on the Hawthorn. The leaflets in the centre 

 are stunted in growth, curl inwards, and provide shelter and food for 

 numerous larva 1 during the summer months. The larvae pupate in the 

 ground, and the gall-flies emerge in the spring. 



Kosette Galls are to be found on several kinds of Willows, and are the 

 work of Cecidomyia rosaria. The single larva feeds upon the end of the 

 shoot, preventing its further growth, and a rosette is formed, consisting of 

 30-60 leaves in all stages of development, the outer ones occasionally 

 being woody. The larva pupates in the gall, and the fly emerges in the 

 spring. 



Cecidomyia marginem-torquens causes the margins of the leaves of Osiers 

 to roll along the under-surface towards the mid-rib. The margins become 

 variously coloured, yellow, red, purple, and chocolate-brown being the pre- 

 vailing tints. The larva? feed in the gall from June to October, pupate in the 

 ground during the winter, and the flies emerge in spring. 



Cecidomyia salicis forms peculiar lemon-shaped swellings on the twigs 

 of Grey Sallow {Salix cinerea), and sometimes the Round-eared Sallow 

 {Salix aarita). The galls are nearly an inch long, and about h in. in diam. 

 The larvae, from three to thirty in number, pupate in the gall, and the imagines 

 emerge in May, leaving about half of the puparium projecting from the hole, 

 after the manner of the Goat Moth when emerging from its cocoon. 



The Gall-mites belonging to the Order Acarina are microscopic creatures 

 which live on plants, by preference in the bud, and produce galls of various 

 descriptions. 



The Black-Currant Mite {Eriophyes (Phytoptus) ribis) causes the buds 



to swell unnaturally, so that they produce neither leaves nor fruit. From 



some infested buds a few stunted leaves may come forth, but they fall in 



the early summer, and no blossoms are formed. The mite is indistinguishable 



with the naked eye, but can be seen with a good pocket lens. The body is 



lviii 





