66 PROTECTION OF PLANTS — 1922-23 



adults as possible should be tri^nsfeVfed at one time and beiSt results have been 

 obtained where they are all placed on one heavily infested tree situated in a 

 central part of the ofchafd. 



Methads No. S: The third method of artificially introducing the disease 

 into an orchard is practised in the sprjing before the blossoms unfold. This 

 consists in transferring the i^esting spores from one orchard to another. The 

 best way in which to do this is to gather the loose pieces of bark, under which 

 the resting spores pass the W/inte^ and to which they closely adhere, and by 

 means of tacks attach them to the upper limbs of the trees to be infected. Care 

 should be taken to fasten the bark scales so as to have the surface on whi c h 

 the sp(ores are born n;ext to the tree and not directed away from it. As in the 

 previous method a large number of spores must be transferred and they should 

 be CQncentr^ated oin one centi;al tree in the orchard under treat,ment. 



Economic Importance of the Fungus. 



In Nova Scotia the Green Apple Bug is a comparatively new pest, having 

 beipn noticed for the first time in June, 1914, but notwithstanding that fact 

 it is DOW considered one of the worst, if not the worst, insect with which the 

 orchardist has to contend. Speaking of the seriousness of this pest Dr. W. H. 

 Brittain in his bulletin entitled "The Green Apple Bug in Nova Scotia" (Bull. 

 No. 8, N. S. Dept. Agric.) says, "The apple crop in the AnnapoHs Valley has 

 not been increasing at the rate one would expect from the new acreage con- 

 stantly reaching bearing age each year. On the contrary, it seems to have, 

 on the whole, actually gone back. There is little doubt in the mind of the 

 writer that this condition of affairs can to a large extent be laid at the door of 

 the Green Apple Bug." 



Since the publication of the above-mentioned bulletin (1917) this insect 

 has been gradually decreasing, not only in the sprayed orchards but just as 

 rapidly in the untreated ones. At that time inv^estigators working on the 

 artificial control of the bug were at a loss to account for this strange and unpre- 

 cedented numerical reduction. Since the discovery of the fungus in 1920, 

 however, the problem has become clear, for it seems quite certain now that 

 the disappearance of the Green Apple Bug was due wholly to the work of this 

 fungal parasite. Studies carried on subsequent to the discovery of the disease 

 have shown that the insect is still decreasing and that the decrease is being 

 brought about by the Empusa in question, which goes to prove the truth of 

 the above theory. With such an important natural control factor availeble 

 and one amenable to artificial dissemination, it seems safe to predict that the 

 Green Apple Bug will never again be as serious a pest in the Annapolis valley 

 as it has been in the past. 



