94 



THE AMERICAN ENTOMOLOGIST. 



pupa Tachina alcticc, n. sp., and 



Sarcophaga sarracenioi Riley ; from the 

 pupa alone — Piinpla conquisitor (Say), 

 Cryptits iiu/ia'us Say, Clialcis ovata Say, 

 Cirrospilus esurus, n. sp., and Didictyum 

 (n. gen.) zigzag, n. sp.* Regarding the 

 theory of the annual dying out of the insect 

 in the States, and the consequent annual 

 migration of the moth thereto from some 

 exotic country — a theory largely based on 

 the above mentioned erroneous opinions, 

 and which Prof. Grote made his own in 

 the paper referred to — Prof. Riley states 

 that the theory was first suggested by Mr. 

 Robert Chisolm of Beaufort, S. C., but 

 first fully propounded in 1847 by Dr. D. B. 

 Gorham in DeBow's Review.f In 1854 it 

 was again set forth by Dr. W. I Burnett in 

 the Proceedings of the Boston Society of 

 Natural History. | The facts collected dur- 

 ing the past year strengthen the belief that 

 the moth hibernates with us, and that no 

 such theory is necessary to explain the 

 phenomena connected with its annual de- 

 velopment. Its comparative absence dur- 

 ing some years and its prevalence in inju- 

 rious numbers during others, are depend- 

 ent on the same natural conditions which 

 govern the same phenomena in many 

 species injurious to vegetation, and notably 

 in the case of the Northern Army Worm 

 {Leucaiiia unipuncta). 



Prof. Riley finds it convenient to divide 

 the cotton belt into ist, the southern or 

 permanent portion, where the first worms 

 annually appear and the moths in all prob- 

 ability hibernate ; 2d, the northern or tem- 

 porary portion, in which the insect does 

 not hibernate, but into which it spreads, 

 either by gradual dispersion or by more 

 sudden migration, from the permanent 

 portion. The dividing line between these 

 two portions must needs be difficult to de- 

 fine, because there is an uncertain region that 

 may, according to season or circumstance, 

 belong to either, and also because of the 

 limited observations that have yet been 

 made. Taking the early appearance of 



* These species have since been described in Canadian 

 Entomologist (Vol. XI, p. 163) and Bulletin 3 of the U. S. 

 Entomological Commission. 



t Vol. III. pp. 535-4:3. % Vol. IV, .316. 



the worms as a basis, the southern portion 

 may be thus roughly defined: Beginning 

 with Texas, it includes the region south of 

 the Galveston, Harrisburg and San Antonio 

 Railroad, excluding perhaps the extreme 

 western portion, but extending somewhat 

 farther north along the river bottoms. In 

 Louisiana and Mississippi it includes the 

 valley of the Mississippi River and its trib- 

 utaries, with uncertain northern limits. In 

 Alabama it is represented by the limestone 

 cotton belt south of Montgomery, though 

 probably extending farther north to the 

 east of that point. In Georgia it does not 

 extend north of Albany on the west, but 

 doubtless includes the sea islands along 

 the coast, as also those of South Carolina, 

 though at the present time cotton cultiva- 

 tion is limited principally to Saint Cathar- 

 ine's Island. In Florida it includes all 

 parts where cotton is grown. 



While the theory of annual immigration 

 does not apply to the first or southern por- 

 tion, Prof. Riley believes that it does ap- 

 ply to the northern portion, and that the 

 insect is there killed out each winter ; so 

 that some of Prof. Grote's arguments have 

 force if restricted to this more northern 

 portion of the belt. 



The interesting fact is recorded that the 

 cotton plant furnishes not only the natu- 

 ral food of the larva, in the leaf ; but like- 

 wise that of the moth, in a sweet liquid 

 exuding from certain glands on the under- 

 side of the leaf, and at the base of the 

 outer lobes of the involucre : also that the 

 tip of the proboscis in the moth is admir- 

 ably adapted to penetrate ripe fruit and 

 that much injury is done to such by the 

 moth. The fact that the first worms of 

 the season usually appear in certain low, 

 moist spots in a field, is explained by the 

 sweet exudation being most copious and 

 most attracting the parent moths there ; 

 also by the greater scarcity in such places 

 of ants, which are very abundant in cotton 

 fields and destructive to the worm when 

 young, or molting, or enfeebled from what- 

 soever cause; while the more rapid devel- 

 opment and multiplication of the insect 

 during moist or rainy weather is, explained 



