SOME FOREST INSECTS IN ABERDEENSHIRE 301 



SOME FOREST INSECTS IN ABERDEENSHIRE. 

 By Walter Ritchie, B.Sc. 



T>HE Large Larch Sawflv {Nematus ericksonii). 



While on a visit to Aboyne in the beginning of August, I 

 found the caterpillars of this Sawfly in clusters in several 

 plantations in the district. In the first instance I found 

 them in the Glentaner Estate, on the larch trees alongside 

 the south Deeside road, about one mile west of the suspen- 

 sion bridge over the River Dee at Aboyne. These trees 

 were about seventy years of age. I showed a number of the 

 caterpillars to Dr R. Stewart Macdougall, who determined 

 them as Nematns ericksonii. Having discovered that this 

 insect was in the neighbourhood, I examined a number of 

 similarly aged larch trees in a plantation on the Forest of 

 Birse Estate, and I found on them caterpillars of the same 

 species here and there throughout the plantation. I also 

 found many Large Larch Sawfly larva; on a young fifteen- 

 year-old larch which I chanced to examine in a narrow strip 

 of woodland on the northern portion of the Ballogie Estate, 

 and also in clusters on a larch tree on the Balfour Estate. 

 The plantation in which the latter occurred was about forty 

 years of age. In ever)' case but one I found the caterpillars 

 on the branches on the sunny side of the trees. The upper 

 branches appeared to be well foliaged, the lower ones only 

 being severely attacked, and in some cases these were com- 

 pletely defoliated. In the beginning of September I also 

 came across quite small caterpillars of N. erichsonii. The 

 female Sawfly lays her eggs in niches cut in young larch 

 shoots, and a number of these were seen curled and withered 

 as a result of the egg-laying. The area over which the 

 caterpillars were dispersed measured about eight square 

 miles. The damage caused by this species in England led 

 to its being placed among the insects scheduled under the 

 Destructive Insects and Pests Order. By this Order the 

 presence of the insect in any plantation must be reported 



