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BETTER FRUIT 



February 



Irregular Emergence of Codling Moth at Hood River 



By Leroy Childs, Entomologist and Plant Pathologist, Hood River Branch Oregon Experiment Station 



The breeding-cage information gained 

 by the writer during the past four 

 years has on many occasions proved 

 decidedly perplexing, and was only of 

 value when carefully weighed with 



[Editor's Note.— The following observations 

 on codling moth in Hood River, by Leroy 

 Childs, entomologist in charge of the Experi- 

 ment Station, during the years of 191 1-15-10-17 

 will prove very interesting and valuable. It 

 should be borne in mind very distinctly thai 

 the conditions refer to Hood River climate, 

 which is very different from almost any other 

 section in the Northwest, being subject to great 

 changes and more variation in weather and 



nerally cooler throughout the entire season. 

 However, some very important facts are well 

 established by Mr. Childs, as indicated in the 

 article. It certainly seems important to call 

 the fruit growers' attention in the Northwest 

 in general to the fart that if the great varia- 

 tion at the time of the emergence in Hood River 

 is due to climatic conditions it is quite likely 

 that more or less variation occurs in other 

 districts. The editor does not mean to say this 

 is a fact, but it looks very likely. The damage 

 from codling moth in several districts was 

 very excessive in the years 1916 and 1917, par- 

 ticularly in 1916, with a heavy damage in 1917. 

 It is the editor's impression that a great many 

 have followed a set spraying program, spray- 

 ing on the same dates every year. Possibly 

 this is the cause of the severe loss. It is quite 

 evident from Mr. Childs' investigation that, 

 owing to the weather conditions, the contiau- 

 ation of the brood may cover a longer period. 

 A great manv fruit growers have believed they 

 can control codling moth by three sprays. In- 

 vestigation as given here is quite conclusive 

 evidence that in some years in Hood River it 

 will take four sprays, possibly five. It is also 

 quite probable that the same conditions may 

 prevail in other districts, and instead of three 

 sprays being sufficient, four or five may be 

 necessarv to effect a satisfactory control of the 

 codling moth. As before stated, the investiga- 

 tion of the codling moth in this article is con- 

 fined to Hood River. It seems reasonable to 

 assume that by reading this article the fruit 

 grower in other sections of the Northwest will 

 be put on his guard and will watch the devel- 

 opment of codling moth more carefully. One 

 other very important feature put forth in this 

 article is "that the average orchardist, for some 

 reason, is frequently not able to determine the 

 proper time for spraying for codling moth, 

 and therefore it is suggested that every district 

 that has not already a trained man to deter- 

 mine the proper time for spraying for codling 

 moth would do well to make arrangements for 

 putting in a sort of experiment station to carry 

 on the work.] 



THIS article includes a brief resume 

 of the observations that have been 

 made relative to the behavior of 

 the codling moth at Hood River, Ore- 

 gon, during the years 1914, 1915, 1916 

 and 1917. The work has been con- 

 ducted for its applicable value chiefly 

 in order that the local orchardists might 

 be supplied with first-hand information 

 on the seasonal progression of this in- 

 sect's activities which would enable 

 them to more intelligently and satis- 

 factorily apply their lead sprays. Not 

 being a major project the investigation 

 lacks many details that would more 

 clearly demonstrate the very wide sea- 

 sonal variations in the life history of 

 this apple insect from one year to 

 another. 



The two most important points that 

 have been brought out in this study are, 

 first, the very decided variation in the 

 emergence of the broods from one sea- 

 son to another and its necessary in- 

 fluence on the timing and applying of 

 sprays in order that control may be en- 

 tirely successful. Secondly, the inves- 

 tigations indicate that sweeping recom- 

 mendations given out often in the form 

 of spring bulletins from a central or 

 distant station are far from meeting the 

 requirements in codling-moth control 

 in the different apple-growing sections 

 of the Pacific Northwest, where vast 

 ranges of conditions are found at rela- 



tively short distances. These ranges, 

 due probably to temperatures varying 

 on account of altitudinal, coastal and 

 interior influences, are such as to war- 

 rant seasonal studies of the insect in 



the different sections in order that a 

 comprehensive knowledge of the in- 

 sect's activities be available for the use 

 of orchardists in their control measures 

 Until such stations of study are main- 

 tained we can expect a great deal of 

 trouble from the codling moth in the 

 different apple-producing districts. 



The variation in the life history of 

 the moth, which influences the timing 

 of sprays, has been found to be of more 

 importance in the control of the second 

 generation of worms than the first 

 brood, as in the case of the latter, con- 

 ditions which retard vegetative growth 

 usually directly influence insect activity 

 with a result the standard spring appli- 

 cations — usually a combination insecti- 

 cide and fungicide — can under most 

 conditions be effectively applied by fol- 

 lowing a prearranged spraying pro- 

 gram. 



The information gained and the 

 points herein discussed have been ob- 

 tained through yearly breeding cage 

 studies and field observations of the 

 different stages in the life cycle of the 

 codling moth. Properly prepared and 

 watched, the breeding cage can be used 

 by the investigator as a good index for 

 the successful timing of sprays in 

 order to get maximum control. How- 

 ever, in the hands of the novice, par- 

 ticularly one who is not very familiar 

 with insect life information gained 

 from the cage can lead one astray. The 

 writer has found some growers who 

 can draw sound deductions, others the 

 following of the information divulged 

 would prove disastrous. 



surrounding general field conditions. 

 As an example of this: In 1915 we ob- 

 served several moths issuing in the 

 breeding cages as early as April 27, due 

 to the fact that about a week of very 

 warm weather occurred at that time. 

 This was followed by cold, rainy 

 weather during the remainder of the 

 spring. No more moths issued in the 

 cages for nearly a month and no eggs 

 were found until May 28. This is only 

 one of many similar observations. 

 When problems arise that puzzle the 

 trained investigator — who can make de- 

 ductions of value only upon consider- 

 ing the problem from all angles — the 

 orchardist stands little chance of gain- 

 ing more than approximate information 

 at best. In the absence of expert advice, 

 however, breeding-cage studies on the 

 part of orchardists are to be encour- 

 aged. Its maintenance not only keeps 

 them more keenly interested in habits 

 and control but if carefully attended to 

 serves as a very good indicator where 

 developments are normal. 



Rreeding cages employed by the 

 writer have been of two kinds: One a 

 box 14x16x20, screened in on jthree 

 sides by ordinary window screening, 

 and the other the actual screening in 

 of the trunks of apple trees which were 

 known to be harboring codling moth; 

 in order to insure a good supply trees 

 were often banded before the brood left 

 the fruit, following which the cages 

 were attached. 



For spring study of the insects' de- 

 velopment, cages were always prepared 

 and stocked with worms during the fall 

 of the year. In so doing no unnecessary 



Spraying up to cover under surfaces of foliage. An angle nozzle is an important 

 attachment, and also aids materially in covering this portion of the foliage. 



