THE WOOD-BORERS 



number of spiders that we found in straws was so large 

 as to afford abundant evidence concerning the degree 

 of surgical skill possessed by the wasps. P. marginatus 

 and P. scelestus, in overpowering their large fierce 

 Lycosids, must sting when and where they can, but 

 most of the spiders taken by rubrocinctum are inoffen- 

 sive creatures, and there is so little need to be careful 



TRYPOXYLON RUBROCINCTUM 



or adroit in dealing with them that she has time and 

 opportunity to sting the exact spot that will give the 

 best results. 



The concentration of the nervous system in the Arach- 

 nida would seem to conduce very strongly to uniform re- 

 sults from the stinging of the wasps. Unlike the larva 



185 



