THE GRAPE PHYLLOXERA IX CALIFORNIA. 



65 



period. Toward the period of hatching the egg becomes darker and 

 the eyespots of the embryo become visible. 



The larva. — In hatching, the young larva (PI. IX, g. h) splits 

 the eggshell from the micropyle lengthwise to about three-fourths 

 of its length. This splitting is more or less gradual and is caused 

 by the thorax and head of the young phylloxera bursting the shell 

 and then gradually enlarging the crack. The larva poises itself at 

 an angle of 45°, with legs and antennas appressed to the body, and 

 slowly eases its way out. It seems to rely simply on a slow side- 

 wise body movement to free itself of the shell. When freed, it 

 spreads the appendages and is then able to walk off. The newly 

 hatched larva is of a pale lemon yellow, with dark claret-colored 

 eyes, composed each of three circular facets and placed in the form 

 of the angles of an equilateral triangle. The body segmentation is 

 quite distinct, more so than in later instars. The shape is oval and 

 very flat. The antennas, as in all forms of the grape phylloxera, are 

 three-jointed. The terminal joint is twice as long as the two basal 

 combined. Xear the apex of the third joint occurs a circular sen- 

 sorium. The beak in early generations reaches to the penultimate 

 or antipenultimate body segment, and in later generations protrudes 

 beyond the caudal segment of the abdomen. The legs and antenna 3 

 bear hairs. Table XV gives measurements for five newly hatched 

 individuals. 



Table XV. — Measurements of newly hatched radieieoles of the grape phylloxera. 

 Walnut Creek, Calif., Oct. 23, 191-' t . 



Individual Xo. 



Length 

 of body. 



Maxi- 

 mum 

 width 

 ofbody. 



Length 

 of beak. 



Length 

 of hind 

 femur. 



Length 



of hind 



tibia. 



Length of antenn 



al joints. 



Length 



of sen- 



sorium. 



1 



2 



3 



1 



Mm. 



0. 359 

 .327 



Mm. 

 0.176 



.179 



Mm. 



0.1964 



.2036 



Mm. 

 0.0679 



Mm. 

 0. 0571 



Mm. 



Mm. 

 0. 0161 

 .0143 

 .0196 

 .0180 

 .0188 

 . 0152 



Mm. 

 0. 0705 

 .0625 

 .0680 

 .0705 

 .0634 

 .0670 



Mm. 



2 



6. 0169 

 .0214 

 .0232 

 . 0188 

 .0179 





3 



.0562 

 . 0580 

 .0566 

 .0554 



.0429 

 .0491 

 .0455 

 .0491 





4 



.359 

 .341 



.189 



.190 



. 2152 

 .2107 







0. 0231 



6 



. 02°s 













The young phylloxeras hatching in spring have shorter beaks than 

 those which hatch in the fall, the beaks in spring averaging in length 

 about 0.155 mm. 



The first molt does not take place until more than half of the grow- 

 ing period is passed. The molting of the radieieoles is a procedure 

 quite similar in detail to the hatching from the egg. After each molt 

 the individual for about 24 hours is brighter in color than at any 

 other time during the instar. After the first molt the phylloxera 

 changes from oval or suboval to pyriform in shape (PL IX, i. /'). 

 1U00°— 21 5 



