422 



W. D. FUNKHOUSER 



species is neither long nor powerful, and in those forms in which the 

 eggs are laid in the stems of trees — which include the larger number of 

 species — the organ either does not reach to the xylem or, reaching it, 

 is not able to penetrate the harder wood and slips to one side, leaving 

 the eggs between the wood and the bark. In the cases in which the 



eggs are laid in buds, the part of the 

 bud chosen is usually the outer 

 scales, which are not thereby pre- 

 vented from performing their func- 

 tions as protective organs and are 

 of little importance in the later de- 

 velopment of the plant. 



A few exceptions to these general 

 conclusions may be noted. The 

 species which has attracted the most 

 attention from an economic stand- 

 point and which is oftenest men- 

 tioned in literature as destructive 

 to trees, is Ceresa buhalus. This 

 species is peculiar in that it lays its 

 eggs in curving, nearly parallel rows, 

 in such a fashion that a definite area 

 is cut out of the bark, which fails to 

 heal and leaves a conspicuous line 

 of scars (fig. 43). These scars per- 

 sist for several years and are occa- 

 sionally infected with fungi and offer 

 an entrance for other insects. The 

 first record of such injury seems to 

 have been made by MarTatt (1887), 

 and is followed by a detailed ac- 

 count, with excellent figures, by the same author (1894). Since that 

 time a long series of references to the scars, particularly on apple trees, 

 has appeared. Hodgkiss (1910) worked out the life history of the species 

 on apple and pear, and credits it with doing considerable damage to 

 the twigs (page 97 of reference cited). The species is very abundant in 

 orchards in the vicinity of Ithaca, particularly in Hook's orchard on 



Fig. 43. 



TWIGS INJURED BY OVIPOSITION OF 



CERESA BUBALUS 

 rhotogiapli by II. H. Knight 



