INSECTS INJURIOUS TO AGRICULTURE. 201 



nates principally under the shelter of rank wire-grass in 

 the more heavily timbered portions of the South, and begins 

 laying its eggs (400 to 500 in number) on the ratoou cotton 

 when this is only an inch or two high. The localities 

 where it hibernates, and where consequently the earliest 

 worms appear, seem to be more common in the western 

 part of the cotton belt (Texas) than in the Atlantic cotton 

 States. It is inferred that from this region the moths emi- 

 grate east and north, laying their eggs later than the original 

 Texan brood, as in Alabama, Georgia, and northward. The 

 recently hatched worms of different sizes were found late in 

 March on ratoon cotton in southern Georgia and Florida, 

 and in late seasons from the middle of April to the middle 

 of May, though they do not attract the attention of planters 

 until the middle or last of June. In midsummer the period 

 from hatching to the time when the moth lays her eggs is 

 less than three weeks, while in spring and late autumn twice 

 that time may be required. There are thus in the northern 

 cotton States at least three "crops" or broods of cater- 

 pillars in a season, while in Texas there are at least seven 

 annual generations. The first generation is only local, but 

 in Texas, says Riley, "The third generation of worms may 

 become, under favoring conditions, not only widespread but 

 disastrous, and the moths produced from them so numerous 

 that they acquire the migrating habit. This generation 

 appears in south Texas during the latter part of June, and 

 in south Alabama and Georgia somewhat later," and this 

 is the first brood which attracts general attention. When 

 the worms are very abundant and the cotton well " ragged," 

 the moths, driven by need of food for their progeny, and 

 with favoring winds, migrate to distant points, and thus 

 spread late in summer northward, and they have been seen 

 as far north as Boston, Buffalo, and Racine, Wis. At the 

 same time these northern specimens are so fresh that they 

 are supposed to have been bred on some unknown northern 

 food-plant. This point is not yet settled. 



The earliest worms are confined to the low lauds and to 



