OF WASHINGTON, VOLUME XVI, 1914 17 



LEAF WORM. 



Next in interest is Alabama argillacea, one full grown larva of 

 which was found on Thurberia in Stone Cabin Canyon, while the 

 species was also found on the extremely isolated patch of cotton 

 at Tucson thirty miles distant to the north, and also in the cotton 

 fields at Phoenix. This species is known to display a tremendous 

 power of flight in its annual northward dispersion. The question 

 of greatest interest is whether the mild winters of Phoenix and Tuc- 

 son will enable it to hibernate in Arizona and be present for the 

 next cotton crop. At Victoria, Texas, Mr. Goad experimentally 

 fed Alabama larvae on his Thurberia plants and in some experi- 

 ments gave them a choice between cotton and Thurberia leaves 

 but found that they fed on both and that they matured normally 

 when fed on the Thurberia. On the other hand they did not seek 

 the Thurberia naturally. 



This insect occurs on cotton in South and Central America and 

 the West Indies, and only comes into the United States in warm 

 seasons. It has never previously been taken on any other food 

 plant than cotton. 



The absence of the cotton worm with the single exception noted, 

 in the sections where the Arizona wild cotton was examined, in- 

 dicates the improbability of the insect being indigenous to Arizona. 

 The discovery of the insect upon cultivated cotton near Tucson 

 the first season of its growth in that locality is almost positive 

 evidence that the moths of this insect had reached Arizona by 

 flight from points hundreds of miles to the south. 



THE THURBERIA BOLL WORM. 



The Thurberia boll worm is considered the most destructive 

 of all the insects found attacking Arizona wild cotton. During 

 the latter part of August the eggs of this Noctuid were very abun- 

 dant in Stone Cabin Canyon in the Santa Rita Range and were 

 also found in Sawmill Canyon a few miles distant, but in this lat- 

 ter locality they were noticeably scarce. In Ventana Canyon in 

 the Santa Cataiina Mountains one of the authors (Morrill) in com- 

 pany with Prof. G. F. Freeman on July 1, 1913, estimated that 

 about a fourth of the old bolls attached to the plants had been 

 eaten out by worms, undiscovered at that time. A single old 

 boll similarly destroyed was found at Fish Creek Canyon in Au- 

 gust. Further evidence of the wide distribution of the insect 

 in Arizona exists in the eggs found upon the herbarium specimens 

 of the National Museum from near Bisbee (probably in Mule 

 Mountains) and from the Rincon Mountains. It is of interest to 

 note that the first of these records is dated September 14, 1892. 



