APPLE PESTS 



515 



from Mediterranean regions to the north- 

 ern limits of apple growing in Siberia, 

 in Southern Africa. Australia, New Zea- 

 land, Tasmania and China, as well as 

 In the United States and Canada, we 

 are forced to recognize the improbability 

 of. perpetually immune regions. Once it 

 gains a foothold the codling moth will 

 thrive wherever the apple can be grown 

 successfully. 



We do not wish to be understood as 

 arguing that the codling moth will be- 

 come equally destructive in all localities, 

 or that its prevalence is independent of 

 climatic conditions. Rather the contrary 

 is true, since the seriousness of its depre- 

 dations varies with both the locality and 

 the season. Temperature is the great fac- 

 tor which controls the abundance of a 

 species in a given locality; hence, as the 

 female moth deposits eggs freely only 

 when the evening temperature is above 60 

 degrees Fahrenheit, we should expect to 

 find, as indeed we do find, that the orch- 

 ards in the coast regions west of the Cas- 

 cades, and those of the inland plateau 

 sections, are less subject to the ravages 

 of the codling moth than those of the in- 

 land valleys. This factor is of but little 

 practical importance, however, and should 

 be given scant consideration in the selec- 

 tion of an orchard site. The probability 

 is that as orchards become more numer- 

 ous, active repressive measures against 

 the codling moth will become necessary. 

 even in the most favored localities. 



Know All Stages — Efficient spraying 

 operations and the proper application of 

 other repressive measures against the 

 codling moth are so intimately linked with 

 Its habits, and these habits so varying, 

 within certain limits, with the locality and 

 the season, that every grower should be- 

 come familiar with it in all of its stages. 

 Unfortunately, however, growers do not 

 seem fully to recognize the importance of 

 such information, or consider it too tech- 

 nical and difficult to obtain. Consequent- 

 ly few actually do know it in any other 

 than the larval or "worm" stage, not- 

 withstanding the fact that a "speaking 

 acquaintance" with all stages is easily 

 acquired. 



The codling moth, in common with 

 many other insects, passes through four 

 sharply defined stages during its develop- 

 ment, viz.: the egg, the larva or "worm," 

 the pupa, and the moth or adult. All 

 four stages from the egg to the moth 

 inclusive constitute a generation or a 

 "brood," and since this cycle from egg to 

 moth is completed twice during the year, 

 the insect is said to pass through two 

 generations yearly, or to be "two 

 brooded." In some of the warmer apple 

 growing sections of the South three 

 broods are reported. During the winter 

 It exists only in the larval state, but dur- 

 ing a greater portion of the summer 

 months it may be found in all four 

 stages. 



The Egg — The eggs, which ai'e laid 

 singly, are minute, nearly circular scale- 

 like objects about one-twentieth of an 

 inch in diameter, pearly white in color 

 and somewhat translucent. They may 

 well be likened to minute trout scales 

 glued to the surface of a leaf or fmit. 

 The surface of the egg, however, is finely 

 wrinkled and so reflects the light that it 

 appears as a minute glistening speck, if 

 the fruit or leaf to which it is attached 

 is held at the correct angle before the 

 eye. In two to four days after oviposi- 

 tion the developing larva becomes dis- 

 tinctly visible as a black spot near the 

 center of this circle and the outline of 

 the whole body is discernible for a day 

 or two before the egg hatches. The eggs 

 hatch in from seven to ten days. 



The Lan-a — When first hatched the 

 young larva is scarcely one-sixteenth of 

 an inch long. The head is large, black 

 and shining; the body is slender, translu- 

 cent white in color and marked with dis- 

 tinct black spots, each of which has a 

 minute bristle. Owing to their minute 

 size and to the fact that they usually 

 enter the fruit very soon after hatching, 

 these young larvae are rarely seen. As 

 the larva develops it molts five times; 

 the color of the head and the thoracic 

 and anal shields turn black to brown, and 

 the body acquires a pinkish tinge. The 

 full-grown larva is about three-fourths of 

 an inch long and one-twelfth of an inch 



