28 



BULLETIN 847, U. S. DEPARTMENT OF AGRICULTURE. 



emergence of the first beetles of about 40 days. On Grand Island, 

 in northern Michigan, the first beetles appeared 75 days after the 

 date of the first appearance in Georgia. In the several years during 

 which beetles were reared at French Creek, W. Va., there was a 

 variation of 13 days in the dates of the first adults to issue. Calendar 

 dates are therefore of little value in expressing the time when a 

 given metamorphic change of the insect takes place. It was found, 

 however, that the time of certain transformations and activities of 

 the borer may be anticipated or determined very conveniently by 

 observing the definite annual steps in .the development of foliage, 

 flowers, and fruit of the apple and other trees upon which the insect 

 lives. 



The first blossoms to appear on apple follow closely the first 

 activities of the borers in the spring and it is just in advance of 

 apple blossoming time that the first fresh castings thrown from 

 trees by borers may be looked for. Also, the blooming time of apple 

 corresponds quite definitely with the pupal period of the insect. The 

 oviposition time of the beetles begins with and extends somewhat 

 beyond the ripening season of the fruit of the service tree. These 

 rules hold good in a general way for all latitudes and altitudes and 

 for early and late springs. 



The following field notes arranged in Table X indicate the coin- 

 cidence of these events in a number of different localities : 



Table X. — Indicating the correspondence in time of certain developmental 

 changes in the roundheaded apple-tree borer and its host trees. 



Locality. 



Date. 



Field note. 



Frenchton, W. Va 



Weston, W. Va 



Great Cacapon, W. Va 



Pickens, W. Va 



Winthrop, Me 



Gadsden, Ala 



Demorest, Ga 



Biltmore,N.C 



French Creek, W. Va. 



r>o , 



Do , 



Munising, Mich 



French Creek, W. Va.. 



Do 



Do 



Apr. 27,1914 



Apr. 28,1914 



May 5, 1914 



May 20,1914 



June 22,1914 



Apr. 29,1915 



May 1, 1915 



May 4,1915 

 Apr. 20,1916 



Apr. 25,1917 



Apr. 27,1917 



June 20, 1917 



Mar. 26,1918 



May 15,1918 



June 13, 1914 



Blossoms of York Imperial and Maiden Blush one-half open. 



One pupa of S. Candida found. 

 Apple trees in full bloom. More than half the transforming 



borers have pupated. 

 Apples a little past full bloom. About 25 fresh pupae of S. 



Candida collected. 

 Three-fourths the apple petals off. Maturing borers all in 



pupal stage. 

 Apple blossoms have been off 2 weeks or more. Pupse of S. 



Candida still present. A few have issued. 

 Apple petals have been off 6 days. One pupa of S. Candida 



found. 

 Apple trees just past full bloom. All maturing S. Candida in 



pupal stage. 

 Do. 

 First apple blossoms opened to-day. Half the transforming 



borers have pupated. 

 First apple blossoms opened Apr. 22. All maturing borers 



have pupated Apr. 25. 

 Borers in apple threw out first castings a few days in advance 



of first apple blossoms. 

 First apple blossoms opening. About a dozen fresh pupse of 

 S. Candida found. 



Apple buds showing first pink. Fresh castings first appear- 

 ing from 1-year-old borers. 

 Last petals falling from apple. Transforming borers all pupm 



except one male which has changed to beetle. 

 First fruit of service ripened May 29. First eggs of S. Candida 



June 4. Fruit of service overripe June 13. Fgg laying of 



S. Candida at height June 13. 



