SOME MITE-GALLS. 205 



XXXI. 

 BIOLOGICAL NOTES, 



BY P. CAMERON. 



[Read 24th November, 1885.] 



I. ON SOME MITE-GALLS. 



1. On Pyrus Aria. — Mr. D. A. Boyd has sent me from 

 Glen Lyon some leaves of Pyrus Aria, Sm., more or 

 less crowded with the galls of a Phytopus, They are 

 visible on both sides of the leaf, forming, on the upper 

 side, irregular white blotches; but are not so con- 

 spicuous on the lower, owing to its white colour. They 

 do not project much ; in size they vary from 1 to 2J 

 mm. As has just been mentioned, their colour is, 

 as a rule, white; but, on the top, the centre of the 

 gall (or rather, the border of the depression) may 

 be red, or more rarely the whole surface may 

 assume a reddish hue. On the upper side there is a 

 depression or hole in the centre of the gall when 

 ripe; and it is covered with longish white hairs, 

 more especially on the lower side. Similar blister- 

 like interlacing galls are not uncommon on Pyrus 

 Aucuparia; but the only record I can find of the 

 occurrence of mite-galls on P. Aria is a notice by 

 Prof. Trail, who records them from near Aberdeen.* 



2. On Artemisia vulgaris. — Near Cambuslang I found 

 on the upper side of the leaves of this plant small 

 mite-galls. They are projecting, and are, on the 

 average, about 1 mm. in length by about half a 

 mm. in diameter. The surface is marked with small 

 irregular projecting points, and covered with short 

 white hair, which is much longer at the base of the 

 galls. At first these are green, but become reddish 

 or brownish with age; and when old, too, they get 

 bent. 



* Scottish Naturalist, iv. 168. 



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