2o8 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



REPORTS BY THE HONORARY 

 SCIENTISTS. 



I. Report by R, Stewart MacDougall, M.A., D.Sc, F.R.S.E., 

 Honorary Constilting Entomologist. 



During the past year two insects, amongst others of minor 

 importance, stand out for special reference, namely the Cockchafer 

 and one of the Gall-Gnats injurious to willows. 



The Cockchafer {Melolontha vulgaris), when present in numbers, 

 is a very troublesome insect in forestry, both beetles and grubs 

 being harmful. The beetles during their flight-time devour the 

 leaves of trees, chiefly broad-leaved species, but the needles of 

 larch, and the male cones of pine and spruce, are also eaten. 

 The grubs are extremely harmful to the roots of young conifers, 

 e.g., pines of various species, spruce, larch, cypress, and in a less 

 degree to silver fir; some broad-leaved species, e.g., beech, are 

 also attacked. The younger roots may be bitten clean through, 

 while older and better grown ones have their bark gnawed away. 

 The leaves of these attacked plants turn yellow, and the whole 

 plant withers away. This discoloration of leaf and withering 

 may not appear immediately in young conifers, and the grubs 

 may have moved to other plants before those, whose roots have 

 been destroyed, show marked signs of withering. That the grubs 

 are at work may also be known by nursery plants being blown 

 over by the wind, owing to their roots being bitten through. 



Description of Insect. 



The beetle is often an inch in length, with the head and front 

 portion of the body black; the wing-cases are reddish brown, 

 hairy, and with five raised lines on each ; along each side of the 

 abdomen are five white triangular marks. The abdomen ends 

 in a prolongation downwardly curved, and not covered by the 

 wing-cases or elytra. The end joints of the short antennae form 

 a kind of club or fan, made up in the male of seven leaves and 

 in the female of six. 



A good idea of the larva or grub may be had from the figure, 

 where a grub is seen at work at the root of a plant. 



