92 



BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 



tlie young radicicole. Caudal segment bluntly rounded. Eyes as in the radi- 

 cicole larva. When the adult issues the single egg within is small, but within 

 three days it becomes very evident (PI. VIII, j) and occupies in section an area 

 equal to about three-fourths of the entire insect. 



Table XXIX. — Measurements of mature sexual females of the grape phylloxera. 



Length of body 



Maximum width of body 



Length of " winter ' ' egg contained 



Maximum width of ''winter" egg contained 



Antennal joint 1, right, length 



Antennaljomt 1, left, length 



Antennal joint 2, right, length 



Antennal joint 2, left, length 



Antennal joint 3, right, length 



Antennal joint 3, left, length 



Mm. 



Mm. 



0.357 



0.464 



.200 



.215 



.313 





.172 





.017 



.0200 



.016 



.0179 



.013 



. 0205 



.013 



.0188 



.054 



.0580 



.053 



.0553 



THE MALE. 



Dusky orange, darker than the sexed female ; antenna?, legs, and genital 

 segment dusky grayish ; eyes of three facets each, red ; beak absent. Body 

 quite noticeably shorter, flatter, and narrower than that of the sexed female, 

 and shorter and narrower than that of the newly hatched radicicole. Genital 

 organ acutely conical. 



Table XXX. — Measurements of mature males of the grape phylloxera. 



Length of body 



Maximum width of body 

 Antennal joint 1, length" . 

 Antennal joint 2, length. . 

 Antennal joint 3, length. . 



Hind tibia, length 



Hind femur, length 



Mm. 

 0.260 

 .094 

 .013 

 .018 

 .065 

 .046 

 .056 



Mm. 

 0.334 

 .154 



.071 



In confinement both sexes at first exhibit a positive phototropism, 

 but after a day of maturity they seek shaded places. At first they 

 are quite active, but later become sluggish. Undoubtedly they are 

 much less active in confinement than in the natural state. 



Table XXXI summarizes the development of the sexed form in the 

 summer and fall of 1911 and 1913. All those which reached the 

 adult state were females. 



Table XXXI. — Summarized record of sex development of the grape phylloxera. 

 Walnut Creek, Calif.. 1911 and 1913. 



Number 

 of indi- 

 viduals. 



Average incubation period 



Average postembryonic period . 

 Average period of development 



5.83 

 11.05 



