THE LEAD-CABLE BORER IN CALIFORISriA. 



15 



shrivel considerably before hatching, which takes place on an average 21 days 

 after oviposition. 



The Labva.9 



First stage ^° (Pis. I and II). — In hatching the young larva cuts 

 or tears a hole in the caudal end of the Q,gg with its caudal spine or 

 saw and backs out into the pore of the wood. It then turns around 

 and if the pore at that point is the proper size for it to obtain a 

 leverage it starts mining. If not, it follows down the pore until it 

 does obtain a suitable leverage. During this stage the larva is not 

 curled as in the later stages. After mining a short distance, from 

 2 to 5 milhmeters, it stof)s and molts to the second stage. The 

 caudal spine is then lost and the curled position assumed. 



Later stages. — The 

 mining proceeds par- 

 allel with the grain 

 of the wood, the bor- 

 ings being packed 

 into the mine behind 

 the larva. Every 

 so often the mining 

 stops and molting 

 to the next stage oc- 

 curs. Apparently 

 six molts in all take 

 place before the 

 larva becomes full 

 grown. (Fig. 11.) 

 During the last stages the larva mines deeper into the wood, return- 

 ing toward the surface just before pupation. It does not mine close 

 to the surface before pupation, however, as do many of the wood- 

 boring roundheads and flatheads, the adults of which are not so able 

 to bite their way through the solid wood. 



In mining the larva assumes the usual curled position and braces 

 itself ventrally with its legs, especially with the spurs on the pro- 

 thoracic pair and with the anal tergite, and dorsally with the thoracic 

 tergites. The head is on a flexible neck and able to move in any 

 direction. The mandibles, by opening and closing laterally, cut the 

 wood into small particles. Some of these are taken into the di- 

 gestive system, but most are passed down to the legs, which deliver 

 them into the scoop-shaped abdominal stemites. The excrement is 



* For detailed description of the larva, by Dr. Adam G. Boving, of the Bureau of Ento- 

 mology, see Appendix, page 49. 



10 R. D. Hartman discovered tlie first-stage larva and the fact that Scobicia has dif- 

 ferent types of larvae. 



Fig. 



11. — The California lead-cable borer: Mature larva. 

 Enlarged 8 times. 



