146 BRITISH OAK GALLS. 



OTHER GALLS ON THE BRITISH OAKS NOT 

 PRODUCED BY CYNIPID^. 



Gall-pits caused by females of Asterolecanium variolosmn, 



E-atzebufg. 



(Plate LXII.) 



Asterolecanium quercicola, Sig. ; Planchonia finihriata, Fons. ; 

 Coccus variolosum, Ratz. ; C. quercicoht, Planchonia quercicola, 

 Bouch., Maskell, Froggatt ; Aster odiaspis variolosus, Boas ; 

 A. quercicola, Bouch, Newstead. 



English name of gall. — " The Pit-making Oak Coccid." 



Position of gall. — On small twigs of Quercas pcchinculata and 

 Q. sessiliflora. 



Manner of growth. — Single, gregarious, coalescent. 



Colour. — Slightly paler than the surrounding part of the twig. 



Average external dimensions of a mature gall = pit. — 

 Height, 1mm. : length, 3 mm. ; lireadth, 2 mm. 



May be sought during the months of May to October. 



These peculiar circular, but mostly ovoid, swellings 

 on oak-twisfs result from external influence. 



They are due to the presence of female Coccidge. 

 These insects pass their life in a fixed spot on the 

 twig, and as the result of their method of feeding, and 

 other causes, irritation is set up in the plant tissues 

 which produces elevated margins of bark around each 

 insect. 



The pits thus formed are relatively very deep, the 

 margins rising suflB.ciently high to conceal the ventral 

 rim of the insect's test. 



These gall-pits may be found in many districts in 

 great numbers. Usually on tender and growing twigs 

 of small scrub-oak bushes among the low and straggling 

 herbage of a roadside bank ; but they not infrequently 

 appear also on terminal twigs of young trees in woods. 



Tits are extremely fond of the insects, and search 

 most diligently for them. When a twig dies, either 

 naturally, or from being severed, the margins of the 

 gall-pits diminish considerably. 



