162 FOREST ENTOMOLOGY. 



Spherical, smooth, and soft currant-Hke mass. j\Iay and June 



Spath eg aster haccarum. 

 Ovoid, slightly ribbed on sides like miniature rifle-bullet 



Apliilotlirix quadrilineata. 



Note. — In the above synoptical table I have largely followed the 

 arrangement of Adler, but I have given only those species I have col- 

 lected, with the exception of Aphilothrix callidoma, which I received 

 from Mr Connold of St Leonards-on-Sea. 



Oak Galls : Their Economic Interest and Teachings. 



With regard to oak galls, or the Cynips, considered as an insect- 

 pest, the only species I have ever found so numerous as to cause 

 appreciable damage was Cynips KoUari. This was in a plot of 

 transplanted oaks in a nursery in Cheshire, and the galls w^ere so 

 abundant that the whole of the trees had to be burned. 



Though individually the species of galls are not, as a rule, so 

 numerically strong as to be looked upon as a pest, yet collectively 

 they give rise to injuries which retard the longitudinal growth, and, 

 in many cases, " prune " the tree into shapes and forms exactly the 

 opposite to what practical forestry requires — as, for example, see 

 fig. 145. Hence they have important associations in practical 

 forestry, as well as interesting biological teachings. 



There is no tree more difficult to train into a straight pole than 

 the oak, and it is just possible that this is often due to the effects 

 of the gall insects ; therefore the best preventive against the injurious 

 effects is to be found in careful cultivation in the nursery and young 

 plantation. The evil practice of selling by height, irrespective of age, 

 has had disastrous results on the sylvicultural growing of oak. Thus 

 it often happens that nurserymen, having height in view, allow seed- 

 lings to grow for three years prior to transplanting, and then after 

 transplanting allow them to stand for three or four years in the 

 nursery - lines, then again transplant, and finally sell individually 

 over several consecutive years. But if the nursery work is bad, 

 the method of planting out by the purchaser is sometimes worse ; 

 for we often see large oaks planted out in a " mixed " plantation, 

 and towering three or four feet above the more hardy species, which 

 were planted under the name of "nurses." Apart from the excellent 



