The Arizona boll weevil is a variety of the well known boll weevil of the South. It is, however, specially adapted physiologically to thrive in arid regions. The natural host plant of the Arizona boll weevil is Thurberia or wild cotton. It has invaded cultivated cotton, however, and is now a serious menace. The injury at presents confined to Pima and Santa Cruz Counties but is likely to spread. It has been demonstrated that the Arizona weevil accepts cultivated cotton readily. This invasion is of the utmost importance. Research work on this pressing problem is now under way.