Galls caused by the larv^ of Cecidomyia saliciperda Duf. 



on 



twigs of Salix Caprea Linn. 



PLATE 26. 

 Synonymy of Insect. 



Cecidomyia terebrans Lw. 



„ saliciperda Theobald. 



albipennis Lw., VVtz., Walker. 



Rhabdophaga vitninalis West. 

 Habitat of the Sallow, or Goat-willow.— Very common 



throughout Britain, by the sides of streams, in marshy 



places, damp open woods, and in thickets and hedges. 

 The Gall is formed by the larvas feeding within the stem, 



causing it to swell, and the bark to crack and burst through 



the epidermis. 

 Position. — On the twigs, usually at or near the top. 

 Manner of Growth. — Singly or in numbers, separately or 



coalescent ; scabious. 

 Colour.— Dark green suffused with red ; light brown. 

 Average Dimensions of a Mature Specimen. 



Length, 20 mm. ; girth, 36 mm. 

 May be sought during any month in the year. 

 The Growth is complete by the end of September. 

 The Typical Condition of the gall is plurilocular. Usual 



number of cells, 6. 

 The LarV/E pupate in the gall. The imagines emerge 



during the spring. 



It is not difficult to find these galls. During the winter is 

 the best time to seek them, the absence of foliage allowing them 

 to be easily detected. They are very irregular in their mode of 

 growth. There may be only one small swelling on a twig, or 

 as many as eight distinct or coalesced swellings within a distance 

 of four inches. Leaf-buds appear on the surface at various 

 points, which, when developed, may have a galled swelling on 

 the petiole. 



The illustration is of specimens gathered at Hastings by 

 the author. 



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