THE ALFALFA CATERPILLAK. 15 
of alfalfa bloom by this butterfly, that possibly its feeding habits 
might be of some benefit in assisting pollination. As this statement 
occasioned some comment, further observations were made upon the 
butterflies during three consecutive years, but not another instance 
of tripping was noted. It seems, therefore, that in the cases ob- 
served, the trippings were effected accidentally by the feet. As 
these instances are probably exceptional it is not likely that the but- 
terflies exert any material influence on seed production. However, 
the relation of bees and alfalfa to butterflies and alfalfa seems to be 
a complex one. Hermann Midler, 1 in 1873, came to the conclusion 
that butterflies probably effect explosion and cross-fertilizatiom 
while C. V. Piper, 2 in 1909, in his Report of the Committee on Breed- 
ing Forage Crops, gives the records from a considerable number of 
well-known plant breeders, no two of whom seem to agree as to the 
exact relation of butterflies to alfalfa pollination, but the majority 
of whom think that the butterflies exert no influence. 3 Whether the 
butterflies rob honeybees of their just food is a question. Prof. 
Cockerell 4 states, in 1899, that * * * "butterflies, sucking the 
nectar, but making^no honey, must interfere with the success of the 
bees, especially when they become very numerous." As mentioned 
above, this robbing of the bees by butterflies is a common belief 
among beekeepers and has been suggested to the author many times. 
NUMBER OF GENERATIONS. 
Mr. W. H. Edwards 5 reports two broods of this species in the 
mountains of northern Colorado, the adults of which appear in 
June and again in the latter part of July and in August. In Ne- 
braska and Illinois, according to the same author, three broods are 
recorded, while in the lowlands of California he reports the insect 
as being triple or quadruple brooded. Mr. J. Boll, 6 in 1880, reports 
four broods in Texas, and this, too, during a short season, for he 
1 Muller, Hermann. Die Befruchtung der Blunien durch Insekten, Leipzig, 1873, p. 
228-229. 
2 Piper, C. V. Report of the committee for breeding forage crops. Alfalfa and its 
improvement by breeding. Amer. Breeders' Assoc, v. 5, 1909, p. 94-115. 
3 Since this manuscript was submitted for publication, Bulletin No. 75 of this depart- 
ment, dated Apr. 8, 1914, treating of Alfalfa Seed Production ; Pollination Studies, by 
Prof. C. V. Piper and his assistants, has been published. 
In this document it is shown that tripping of alfalfa flowers may be automatic as well 
as effected by insects or other external agents. The authors state that this automatic 
tripping takes place more frequently in hot sunshine, although humidity is doubtless a 
factor. Also the statement is made that this automatic tripping, with consequent self- 
pollination, probably results in the setting of as many pods as does tripping by insect 
visitors, at least in the West. — F. M. W. 
4 Cockerell, T. D. A. Some insect pests of Salt River Valley and the remedies for them. 
Ariz. Agr. Expt. Sta. Bui. 32, p. 273-295, Dec, 1899. 
5 Edwards, W. H. The Butterflies of North America, second series, Boston, 1884, 
Colias IV. 
Boll, J. Ueber Dimorphismus und Variation einiger Schmetterlinge Nord-Amerikas. 
Deut. Ent. Ztschr., Bd. 24, Heft 2, p. 243-248, 1880. 
