NATURAL 



FEBRUARY 2006 



March of the Weevils 



How a Mexican beetle launched 



a hundred-year attack on United States cotton 



By Robert W. Jones 



More than a hundred years ago, a curious- 

 looknig insect appeared in the United 

 States that would dramatically transform 

 the economy and landscape of the cotton-depen- 

 dent South. The first report from the front lines of 

 the unfolding U.S. invasion came in October 1894. 

 That's when a small vial of insects arrived at the 

 headquarters of the U.S. Department of Agricul- 

 ture (USDA) in Washington, D.C., sent by a phar- 

 macist named Charles W. DeRyee from Corpus 

 Christi, Texas, hi those days, farmers made insec- 

 ticides from chemical ingredients they bought at a 

 local drugstore. When a new and perplexing pest 

 had appeared on cotton farms near Corpus Christi, 

 local farmers had naturally turned to DeRyee tor 

 help. The pharmacist, m turn, sent the offending 

 insects off to the USDA, accompanied by a trou- 

 bling note that described damage to the fruits grow- 

 ing at the top of the area s cotton plants: 



The "Top" crop of cotton of this section has been very 

 much damaged and in some cases almost entirely de- 

 stroyed by a peculiar weevil or bug which by some means 

 destroys the squares and small bolls. Our farmers can com- 

 bat the cotton worm but are at a loss to know what to do 

 to overcome this pest. 



An insect taxonomist at the USDA, Eugene A. 

 Schwarz, identified the "peculiar weevil" as An- 

 thotwmns gmiidis, i member of the Curcuhonidae, 

 or "snout beetle" family, so-named for its mem- 

 bers' unique, elongated snouts. When Schwarz and, 

 independently, C.H.Tyler Townsend, an entomol- 

 ogist from New Mexico College of Agriculture and 

 Mechanical Arts (now New Mexico State Univer- 

 sity) in Las Cruces, went to Texas to observe the 

 weevil and the damage it caused, they quickly re- 

 alized the animal's destructive power and alerted the 

 world to the threat it posed to cotton production. 



What those investigators saw is charac- 

 teristic weevil activity. Adults pierce the 

 flower buds, or "squares," with their long 

 snouts and eat the pollen within. They also 

 puncture the immature fruits, or "bolls," to 

 consume the developing cotton fiber. More 

 important, the females bore holes deep in- 

 to both squares and boUs to deposit their 

 eggs. After hatching, the larvae consume the 

 innards of the plant's reproductive struc- 

 tures. Damaged squares are then severed 

 from the plant, never to become bolls. And 

 most of the damaged boUs fail to produce 

 their trademark fluffy fibers. AiithoHoiniis gmndis, a 

 modest, quarter-mch-long insect, soon became 

 known as the notorious cotton boll weevil. 



The appearance of a field heavily infested by 

 weevils is a depressing sight to any cotton 

 farmer, but it must have been devastating to those 

 who first witnessed the destruction. When weevils 

 are finished with a cotton plant, the plant retains 

 its lush, green foliage, but it has none of its distinc- 

 tive large, white and pale-pink flowers or fiber- 

 producing fruits. Yellowed, weevil-infested buds are 

 scattered over the ground like confetti. 



Yet even for the cotton farmers who first sur- 

 veyed such depredations, it would have been hard 

 to imagine the sweeping trajectory of the weevil's 

 invasion. From their fields it marched across the 

 South, leaving massive agricultural and economic 

 disruption in its wake. Even today the cost of the 

 pest in crop losses and control measures in the U.S. 

 is estimated at around $150 milhon a year, and the 

 cumulative costs of the invasion exceed $22 billion. 

 Fortunately for U.S. cotton growers, the war on the 

 boll weevil, begun more than a century ago, is fi- 

 nally being won. The insect has been eradicated 



30 



NATURAI HISTOHY February 2006 



