Galls caused by the larvae of Cecidomyia tiliae Schrk. 



on 



the twigs of Tilia grandifolla Ehrh. 

 PLATE SO. 

 Synonymy of Insect. 



Cecidoviyia limbivolens Macq. 

 „ excavans Macq. 



„ tilicB Theobald. 



Habitat of Tilia Grandifolia.— This tree occurs through- 

 out Britain in woods, parks, avenues, etc. It is profuse in 



its foliage and flowers, and assumes handsome and noble 



proportions. 

 The Gall is formed by the ova being deposited in a bud ; 



the larva, when hatched, feed upon the interior and prevent 



development. 

 Position. ^At the axils of young twigs, and sometimes on the 



petiole. 

 Manner of Growth. — Sessile ; glabrous ; more or less globular. 

 Colour. — Green, greenish yellow, orange-yellow, bright red. 

 Average Dimensions of a Mature Specimen. 



Length, lo mm.; Girth, 15 mm. 

 May be sought during the months of June to October. 

 The Growth is complete by the end of July. 

 The Typical Condition of the gall is plurilocular. Usual 



number of cells, 20. 

 The Larv.e pupate in the gall. The imagines emerge 



during August. 



On young shoots which grow around the stumps of lime- 

 trees, these galls may also be found. They are somewhat 

 variable in shape, mostly quite globular ; others, however, are 

 oblong, and occasionally specimens are to be found spindle- 

 shaped. Their bright colouring causes them to be very notice- 

 able against the beautiful green of the leaves of the tree. It is 

 remarkable what a large number of larval cells are enclosed 

 within a specimen of average size. 



The illustration is of specimens gathered at Aylsham, Norfolk, 

 by the author. 



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