ROSACEA 



65 



vegetable matter, and is often found in ants' 

 nests. Roses and Oaks are peculiarly liable to the 

 attacks of Gall-flies, and the Wild Rose frequently 

 bears a green mossy excrescence, as large or 

 larger than a walnut, called a bedeguar. This 

 shelters the grub of a Saw-fly (Rhodites rosce). 

 The fly is black, with four greyish transparent 

 wings, a red abdomen tipped with black, and 

 red legs, more or less black at the base. But gall- 

 making insects are infested by parasites to a most 

 extraordinary extent ; and a great variety of small 

 Ichneumon-flies, with four transparent wings, but 

 in many cases brilliantly coloured bodies, may be 

 bred from the bedeguar, or from other galls, besides, 

 or instead of, the original occupant for which it 

 was intended. 



Roses are also very liable to be attacked by 

 swarms of Aphides ; plant-lice, or smother-flies, as 

 they are frequently called ; and the leaves and 

 shoots are sometimes completely covered with these 

 small green winged or wingless insects, and their 

 sweet sticky secretion called honeydew. 



The solitary Wild Bees belonging to the genus 



Megachile cut neat circular pieces out of rose- 

 leaves, as well as from other leaves and flowers, to 

 line the burrows in which they deposit eggs and 

 food for their grubs when hatched. 



Service Tree — Sorbus domestica 



(Plate XXXIV) 



This is a tree which grows to a height of upwards 

 of thirty feet. It is scarcely to be regarded as 

 indigenous in England, but it is common in many 

 parts of the Continent, especially in mountainous 

 districts, and is largely cultivated for the sake of 

 its fruit, which is extremely astringent when raw, 

 but when cooked is much esteemed. It is also 

 used to prepare a fermented drink. The bark is 

 smooth, and ashy-grey ; the young shoots are 

 downy. The flowers are placed in clusters at the 

 end of a branch, and expand in May and June. 

 They are white, with 5 styles, and the fruit 

 resembles a small red pear, with 5 seeds. The 

 wood forms valuable timber. 



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