MARBLE-GALL FLY ; COMMON SPANGLE GALL. 237 



on low-growing Oak — such as trees stunted hy want of shelter 

 from sea-blasts or by other causes ; Oak bushes in underwood 

 and hedgerows ; the shoots upon the stumps of felled trees ; 

 and also on young trees, and is especially undesirable in Oak 

 nurseries. 



It has been recommended to employ children to break off 

 the galls before they are full-grown, and thus destroy the 

 insect within in its maggot state ; but this is but a rough 

 remedy for the children would probably break off every leaf with 

 the gall attached. It would answer better in nursery manage- 

 ment for a man furnished with a common penknife to go 

 through the trees whilst the galls were still young, and with a 

 touch of the knife remove the gall without injuring the leaf. 

 The operation would be an effectual cure, and very rapidly 

 performed. In cases where the galls are formed in clusters of 

 three or four to perhaps eight or ten it is desirable to cut the 

 shoot off" below the cluster. If the galls are cut off whilst 

 they are still soft and young, there is no need to take the 

 trouble to burn them ; they will dry and shrivel, and the 

 maggot within will perish. The encouragement of the Tom 

 Tit, or Blue-headed Titmouse, and also of the Black-headed 

 Titmouse, is an excellent means of prevention of increase of 

 these Gall Flies in Oak nurseries. Where galls are numerous 

 these birds are of great service, by making a rough hole in the 

 gall and picking out the contained maggot. 



Other larvas or maggots, besides that of the Cynifs kollari, 

 are often to be found in these galls, sometimes what are 

 known as " inquilines," or fellow-lodgers, which are dispersed 

 in small cells through the substance of the gall ; sometimes 

 parasite larvae, feeding on the larva of Cijnips kollari in the 

 large central cell. 



Common Spangle Gall. Neuroterus lentuularis, 01. 



Common S^mngle Gall on Oak leaf, nat. size and magnified ; also in 

 section, magnified. 



