319 



the whole plan! rai'cly roacliing a lu'iglir of more than two 

 and a half or three feet. 



This plant, like others in the locality, has considerable 

 powers for resistance to drought, for here many months may 

 pass between rains. Under such circnmstances, the Eiiphorh'm 

 may lose its leaves and remain leafless. Branches broken 

 down but not entirely separated from the parent plant may 

 have their wounds closed with the copious milky juice and 

 callous over without dying. 



Xcoc^i/fdrJiis apparently does not attack the living plant but 

 only the freshly dead stems before they are too much weathered. 

 It is probable that the conditions prevailing in this regicm 

 furnish this insect more material to breed in than ever was 

 availalde before the natural conditions were changed. The 

 season of 1910, having l)een abnormally drv led to the death 

 of an unusually large number of the plants. Three things 

 were observed killing the plants or putting their branches in 

 condition for Neodytarlus to breed in. 



All armoured scale, as yet undetermined, occasionally be- 

 comes numerous enough at the base of the plant to kill it. 

 Even if it does not kill the plant it may so weaken it that 

 the immigrant Ceranibycid, LagocJicirus obsoJetus Thomson,may 

 attack the weakened stems. This sjiecies frequently attacks 

 the plant and completes its transformations after destroying the 

 main stem and Itranches while the plant is living, the tiner 

 twigs being still green and flowing with the milky juice. The 

 attack, however, ultimately results in the death of the plant 

 and its utilization by the NeoclyinrJus: Many ])lanis unfavor- 

 ably situated may be so weakened by drought as to fall victim 

 to these beetles without previous injury by the scale insect. 

 The presence of cattle on this area results in a great deal of 

 mechanical injury through their trampling, many branches 

 being broken off and the whole plant often broken down, yet 

 putting many branches in condition for the Neoclytarlus to 

 lireed in. Whiitever the cause of dying may be, the XcorJy- 

 idfhis utili/es a plant (jiiite thoroughly before it has time to 



