BULLETIN 195. 



CALIFORNIA GRAPE ROOT- WORM. 



15 



feet. They apparently remain dormant during the winter season, 

 changing to pupae the following spring. Some full grown larvae of the 

 preceding year were found about the roots as late as May 29th during 

 1907. 



The Pupa. The full grown larva which has wintered over in the 

 ground changes to the pupa in the early spring. The larvae upon reach- 

 ing maturity ascend toward the surface for pupation. The pupae taken 

 this past season were 

 found at a depth vary- 

 ing from four to eight 

 inches below the sur- 

 face. The depth de- 

 pends somewhat upon 

 the amount of mois- 

 ture near the surface. 

 Those found nearer the 

 surface were taken 

 from where there was 

 considerable moisture 

 to within two or three 

 inches from the sur- 

 face. The pupae, being 

 covered with a delicate 

 white skin, require a 

 fairly moist soil to pre- 

 vent them from drying 

 or shriveling up. We 

 met with this difficulty 

 of drying with some of 

 the pupae taken to the 

 laboratory. 



About two weeks is 

 required for the devel- 

 opment of the insect in 

 the pupa stage. The first adult beetles seen in 1907 and 1.908 were dis- 

 covered about May 1st, so that pupation must have begun about the 

 middle of April. The insect may, however, remain in the pupa stage 

 for a month or more. 



The pupa simply rests in a little cell hollowed out by the larva, 

 and any disturbance of the earth is very likely to break this cell and 

 expose the pupa, which on account of its delicate structure will usually 

 succumb to such treatment. 

 2 BULL. 195 



FIG. 11. 



Tip of a shoot, with the leaves, stem, petioles and 

 pedicels attacked by the root beetle. 



