BETTER FRUIT 



EDITOR: W. H. WALTON 

 STATE ASSOCIATE EDITORS 



OKEGON— C. I. Lewis, Horticulturist. 



WASHINGTON — Dr. A. L. Melauder. Entomologist; 

 O. M. Morris. Horticulturist. Pullman. 



COLORADO — C. P. Gillette. Director and Entomologist: 

 E. B. House. Irrigation Expert. State Agricultural College. 

 Fort Collins. 



ARIZONA— F. J. Crlder. Horticulturist. Tucson. 



MONTANA— H. Thomber. Victor. 



CALIFORNIA— C. W. Woodworth. Entomologist. Berke- 

 ley; W. H. Volck, Entomologist. Watsonville; Leon D. 



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Entered as second-class matter April 22, 1918, 



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Volume XV 



Portland, Oregon, November, 1920 



Number 5 



Codling Moth Control in British Columbia 



By R. C. Treherne, Entomologist in Charge for B. C. Dominion Department of Agriculture, and 

 H. H. Evans, District Field Inspector, Provincial Department of Agriculture 



THE great object that Department of 

 Agriculture officials, both Federal 

 and Provincial, in Rritish Colum- 

 bia have always carried before them in 

 handling the codling moth situation is 

 the eradication of incipient outbreaks. 

 In a broad aspect the work may be 

 divided into two channels. (1) The 

 control, by eradication methods, of in- 

 cipient centers of infestation. (2) The 

 prevention of the importation of the 

 moth by infested railway fruit cars. 

 The life history studies of the moth 

 may also be considered a third aspect 

 of the work confronting those engaged 

 in the control operations in Rritish Co- 

 lumbia, but inasmuch as this work is 

 undertaken only to a point where the 

 information gathered would assist in 

 the control operations, this phase may 

 be considered only as an accessory 

 motive to the eradication procedures. 

 Fortunately, in Rritish Columbia, while 

 several of the so-called "incipient" out- 

 breaks have been prolonged over a 

 period of from six to ten years, we 

 still consider that the moth is not an 

 established pest. Certainly it is a fact 

 that the codling moth is not yet a mat- 

 ter of concern to the fruit growers as 

 a whole on their individual holdings. 

 The basis for this satisfactory state of 

 affairs was established several years 

 ago by former officials of the Depart- 

 ment of Agriculture who realized the 

 hold this moth was capable of obtain- 

 ing in apple and pear raising districts 

 and who instituted measures to prevent 

 its spread. The present executives now 

 engaged in the control operations can 

 only be said to have continued the work 

 previously laid down, and to have per- 

 fected the system by educational and 

 field operations. We do not, for a mo- 

 ment, wish the idea to go abroad that 

 Rritish Columbia has devised any new 

 or startling method of control. We 

 have merely realized the serious loss 

 this insect is capable of causing, draw- 

 ing our opinions from observations 

 gathered from apple raising sections of 

 the United States and Eastern Canada, 

 and having a full realization of the pos- 

 sibilities, have adopted measures be- 

 fore the insect had a chance to become 

 established. We are under a great debt 

 of gratitude to our friends in the North- 

 western United States who have freely 



supplied us with information on this 

 insect, particularly as regards losses oc- 

 casioned in the orchard and life history 

 records. Our life history notes, in 

 British Columbia, are by no means per- 

 fect owing to the paucity of material 

 available for study and to the dangers 

 of breeding the moth in areas which 

 are either not infested or where eradi- 

 cation measures are in operation. In 

 return for the information that we have 

 obtained by direct and indirect means 

 from the Northwestern United States 

 we are very willing to supply any en- 

 tomologist, field inspector or orchard 

 section with information gathered from 

 our work, both as regards modes of 

 operation and costs, in the belief that 

 while infestations of long standing are 

 difficult to handle, young orchard sec- 

 tions may find the information of great 

 value. 



Outbreaks of Codling Moth. Four- 

 teen distinct and separate outbreaks 

 have occurred in British Columbia since 

 1905. Today only one serious center 

 of infestation is known to be present 

 and that occurs in the interior sections 

 of the province. Larvae have been 

 taken and occur, at this time, at one or 

 two coastal points, but their presence 

 does not occasion much worry, inas- 

 much as the humidity and temperature 

 records are not suitable for a rapid 

 multiplication of the insect. Our 

 greatest concern is the dry interior, 

 where temperature conditions are emi- 

 nently suited to a rapid and productive 

 multiplication of the insect, but, as we 

 have said, only one center of infesta- 

 tion now occurs in this section. As 

 may be supposed, conditions best suited 

 to the moth are also best suited for 

 tree fruit production for it is in the 

 dry sections of the interior that our 

 best tree fruit sections are located. Ap- 

 proximately 40,000 codling moth larvae 

 have been destroped in British Colum- 

 bia since 1908, the great majority being 

 taken in the Okanagan Valley. The 

 greatest number taken in the Okanagan 

 \';il U'v in a single year totalled nearly 

 10,000 (1915). This number has been 

 reduced to such an extent by vigorous 

 eradication measures that in 1919, last 

 year, only 337 larvae were taken, and 

 of this number we feel morally certain 

 that 150 resulted from a new migration 



from infested railway cars during the 

 year. During 1920 until the close of 

 September only 40 larvae have been 

 taken in the infested area in the Okan- 

 agan Valley. 



We are, therefore, able to state that 

 the codling moth may be eradicated, 

 given the proper measures, and the full 

 co-operation of the growers. 



Life History Records. As stated be- 

 fore, life history records have been 

 kept simply to ascertain the correct 

 dates for spraying. We do not claim 

 to have obtained a full and complete 

 statement of the bionomics of the moth. 

 Such records as we do possess are 

 limited by the extra careful and to 

 some extent unnatural methods of 

 breeding. 



In general, it may be stated that two 

 complete broods usually occur, al- 

 though our laboratory records do show 

 that a single generation is not un- 

 common. 



1916. The winter of 1915-16 was an ex- 

 ceptionally severe one and all codling 

 moth larvae wintering above snowline 

 were killed. It was observed that with 

 smooth bark young apple trees the 

 majority of the larvae spun up at 

 ground level or in the soil nearby. The 

 survivals from the winter arose from 

 these larvae. In old trees with cor- 

 rugated bark the mortality was very 

 high. (Note — This indicates that in 

 young orchard sections the value of the 

 control operations by banding and band 

 examinations is somewhat curtailed and 

 made more difficult.) The spring opened 

 favorably but was cool, and the blos- 

 soming period of apples took place from 

 the first to the middle of May, and 

 calyx spraying operations occurred 

 from the middle to the end of thai 

 month. Codling moth adults were fly- 

 ing during the first two weeks of June 

 until late in July, and full grown lar- 

 vae were taken on July 11. Larvae com- 

 menced to leave the fruit about July 

 18. Adults bred from pupae collected 

 in the field commenced flying on Au- 

 gust 1, although a slight emergence look 

 place on July -'>. This was the start 

 of the second generation, with larvae 

 of this generation present from mid-Au- 

 gust until Autumn. Out of 116 larvae, 

 whose histories were correctly re- 

 corded this year, 73 per cent were 



