18 BULLETIX 124. U. S. DEPAEIMEXT OF AGEICULIVEE. 
HIBERNATION. 
According to earlier records by Edwards and those a little later 
by Scudder. which treat of the species in its northern rather than 
in its southern range, the alfalfa caterpillar hibernates as larva? and 
adults, whereas G\ H. French. 1 in his revised edition of Butterflies 
of Eastern United States, reports the species as hibernating a? 
chrysalids. The writer has observed the species hibernating in all 
three forms, if it could really at all times be termed hibernation. 
Hibernating chrysalids were found upon weed and alfalfa stems by 
the writer at both Tempe. Ariz., and El Centro. CaL. and at TTelling- 
ton. Kans.. Mr. Kelly reported the finding of hibernating pupa? be- 
neath fence rails. Just a few larva? have been collected by sweeping 
at various times during the winter season at Tempe. During the 
last week in January. 1912. a single larva was taken, while in Janu- 
ary. 1913. Mr. R. X. TTilson took a third-instar larva less than two 
weeks after a very severe cold spell, i. e.. severe for the Salt River 
Valley, a temperature of 13" F. having been recorded on two suc- 
cessive nights. On warm days adults have been observed in flight 
several tunes during the winters when the species was under obser- 
vation. In 1910 adults were taken at Tempe early in December, and 
Mr. W. E. Packard took them during the third week in December at 
El Centro. Cal. In the winter of 1911-12 adults were seen on the 
20th of December and again in the middle of January. Larva? have 
been collected in January and. pupating within a few weeks, have 
issued early in March. Pupa? collected in December have issued in 
February, but adults have never been noted to deposit eggs during 
the month of January. It is thus seen that at times hibernation 
amounts to nothing but a prolongation of one of the three stages, 
the usual activity for each respective stage being resumed on warm 
days that occur during the hibernation period. 
According to Boll 2 the species a?stivates in Texas as larva? during 
the dry period in summer when the food supply has become ex- 
hausted. The writer has never witnessed the aestivation of this spe- 
cies in the Southwest. In fact, it has always occurred in most 
abundance during the hotest months of the year, notably July and 
August. Other bureau records likewise show no report of aestiva- 
tion. It seems safe to assume that the change in habit from that 
early reported by Boll in Texas is due to recent irrigation of tracts 
of land well distributed over the arid regions of the Southwest. 
Originally the species had to a?stivate during summer when clovers 
1 French, G. H. The Butterflies of the Eastern United States. New and rev. ed.. Phila- 
delphia. 1900. p. 130. 
2 Boll, J. Eeber Dimorphismus und Variation einiger Schmetterlinge Xord Amerikas. 
Deut. Ent. Ztschr.. Bd. 24, Heft 2. p. 241-24S. 1SS0. 
