140 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



The control measures now being taken on the Sands consist 

 in the trapping of Bylobius, Hylastes, and Pityogenes, and the 

 whole aim of that work is so to reduce the injurious insect 

 population as to prevent any serious invasion of the young 

 plantations by these insects. 



The Culbin Sands thus may afford an interesting experiment 

 in forest entomology, but they also show how important a 

 knowledge of insect conditions in our woodlands may be. Ever 

 since the Gipsy and Brown-tail moths caused the American 

 entomologists to study the whole forest insect complex in 

 relation to the outbreaks of these pests, the trend of forest 

 entomology has been towards protection and prevention rather 

 than remedy. 



The important part played by insectivorous mammals and 

 birds, and by predaceous and parasitic insects, in keeping insect 

 pests within bounds is being more and more recognised, and 

 while the checking of insect outbreaks which have once arisen 

 will always be a difficult task, there is evidence to show that 

 the prevention of outbreaks by the encouragement of insectivorous 

 birds and parasites is a practical possibility. The remarkable 

 reports from the Seebach and Kammerforst forests in Austria 

 where, as a result of intensive bird protection, these forests stand 

 out like a green island amidst the leafless surrounding woods,, 

 defoliated by the Pale Tussock moth, Dasychira pudibunda^ 

 and the accumulating evidence which shows that the Nun and 

 Pine Beauty moths in Saxony are kept in check by Tachinid- 

 and Ichneumonid parasites, all indicate that the biological 

 methods of control, as they are called, deserve the fullest 

 consideration. Following America's lead Germany established 

 in 19 1 9 its first entomological field research station, and this 

 station was established not by the State but by the community 

 of Guben to investigate on the spot the factors determining the 

 origin of outbreaks of the "Pine Spinner," Bomhyx pint. In 

 the Communal forests, Bavaria (Munich), attention is now being 

 given to birds in relation to insect outbreaks and to the insect 

 fauna of the forest floor vegetation, because it is realised that 

 the various insects composing that fauna may have an im- 

 portant relation to the abundance or scarcity of parasitic enemies 

 of such pests as the Nun moth and Pine Beauty moth. 



In this country such work would probably appear to be of 

 academic rather than practical interest, but it must be borne in 



