APPLE PESTS 



52S 



The Larvae or Woruis 



The larvae do not all hatch at once, 

 those in the warmer situations being the 

 first to emerge, and those coming from a 

 single egg patch usually vary several 

 days In their date of emergence. 



The date of hatching is by no means con- 

 stant, but is determined by the earliness 

 or lateness of the season, exactly as is the 

 time for the opening of the buds. The 

 earliest of the larvae emerge with the first 

 bursting of the buds of the apple trees, 

 and when the blossom buds of the apple 

 begin to show their pink color the larvae 

 of the leaf roller have mostly hatched. 

 The active hatching season is usually dis- 

 tributed over about one week to ten days, 

 the time varying with the temperature. 

 If the days and nights are cool, the period 

 lasts longer than if hatching takes place 

 at a time when the days and nights are 

 warm. 



At first the larvae are very small, hard- 

 ly one-sixteenth of an inch in length, and 

 dull greenish-yellow in color, with black 

 heads. As they feed and grow, they be- 

 come deeper green in color, and the black 

 head and first segment of the body above 

 become quite conspicuous. 



On hatching, the little larva goes at once 

 in search of food, and may eat into an 

 unopened bud or find its way into one of 

 the folds of the tender unfolding leaves, 

 which it soon ties together with delicate 

 silken threads of its own manufacture. 

 Thirty days of feeding are sufficient to 

 mature the larva, which then ceases to 

 feed, and in a few days more changes to 

 the third, or chrysalis (pupal), stage, 

 usually among the curled leaves which It 

 has tied together with the silk threads 

 above mentioned. 



The Moth 



The moths measure from three- 

 eighths to four-eighths of an inch in 

 length with the wings closed; the ex- 

 panse of the full-spread wings usually 

 varies between eleven-sixteenths and one 

 inch, the prevailing color is a rusty brown, 

 varying in typical specimens from rather 

 light to quite dark, and there is always 

 present a large pale-yellow to almost 



white diagonal patch on the front margin 

 of the wing a little beyond the middle. 



Natural Enemies 



The fruit tree leaf roller has numerous 

 bird and insect foes which tend to hold it 

 in check. The various bird enemies are 

 the blue bird, robin, catbird, red-winged 

 blackbird, oriole, kingbird, phoebe and 

 English sparrow. 



The fruit tree leaf roller in the larval 

 stage has been found difficult of con- 

 trol because of the manner in which the 

 larvae feed on the foliage and fruit, and 

 also on account of the fact that they are 

 very resistant to poison sprays. Applica- 

 tions of arsenicals alone and in combina- 

 tion with 40 per cent nicotine solution 

 have greatly reduced the amount of in- 

 jury to the fruit and foliage, but these 

 sprays have not been so effective as is de- 

 sirable. 



A series of experiments for the destruc- 

 tion of the egg masses, conducted dur- 

 ing the dormant season, have shown the 

 value of mineral oils. Kerosene emul- 

 sion, crude-petroleum emulsion, and ml- 

 scible oils have been tested. The last 

 mentioned, when used at the strength 

 commonly employed against the San Jose 

 scale — that is. 1 gallon to 15 gallons of 

 water — will prevent most of the eggs 

 from hatching. From 93.23 to 96.21 per 

 cent of the egg masses were destroyed by 

 this material on the experimental plats. 

 Good results also were obtained by the 

 use of kerosene and crude-petroleum 

 emulsions, although these substances 

 were, on the whole, not quite equal to 

 the miscible oils. The ease with which 

 sprays may be prepared from these last 

 commend them to many orchardists al- 

 though the home made emulsions are 

 cheaper. In preparing a kerosene or 

 crude-petroleum emulsion care is neces- 

 sary to insure a thorough and stable 

 emulsion. 



It should be stated that injury to trees 

 treated with oils sometimes follows, al- 

 though no such injury was noted in con- 

 nection with the present experiments. No 

 more spray should be used than is neces- 

 sary properly to treat the tree, and the 



