582 
Journal of Agr icultural Research 
Vol. XXIX, No. 12 
Duration of the larval stage.— 
The length of the larval stage seems to 
depend mainly upon the temperature 
conditions. While in midsummer the 
stage may not require more than 11 
days, in the early spring records of 
periods as long as 41 days have some¬ 
times been obtained. Records ob¬ 
tained at Quincy, Fla., May 12 to 
July 16, 1922, are concisely set forth in 
Table II, which shows for each of 50 
larvae the relative length of the three 
in stars and the complete larval stage. 
THE PUPA 
When first transformed, the pupa is 
white in color and of the same approxi¬ 
mate size as the beetle. During the 
resting stage the development can be 
plainly traced and the approximate 
age of the pupa readily determined. 
In summer the stages of development 
are as follows: First day, white all 
over; second day, compound eyes ap¬ 
parently dotted all over with reddish- 
brown; third day, all of compound eyes 
reddish-brown and tips of mandibles 
beginning to show a slight reddish 
color; fourth day, eyes almost black, 
tips of mandibles a dark reddish-brown, 
femur-tibial joint of each leg yellowish- 
brown, tarsi of legs very light brown, 
and entire body has taken on a dirty 
grayish appearance with the exception 
of the abdomen, which is, still white; 
fifth day, parts showing color on the 
fourth day gradually darken until 
imago appears. 
The length of the pupal stage is 
much shorter than that of the larval 
stage, but is also dependent to a 
certain extent upon temperature, and 
probably moisture, conditions. Pupal 
records obtained at Quincy, Fla., at 
various seasons of the year show a 
duration of from 4 to 11 days. The 
average length of this stage during the 
summer is approximately 5 days. 
The pupal record of 40 individuals 
taken at Quincy, Fla., May 28 to 
July 21, 1922, is shown in Table III. 
THE ADULT 
Feeding habits. —When transfor¬ 
mation to the adult stage has taken 
place, the beetles lie inactive within 
their cells from one to two days. 
Emergence then takes place, after 
which they rest for a period of about 
24 hours. For several days after 
emergence the young beetles can be 
distinguished from those of the older 
generation by the fact that they are 
lighter and brighter in color and smaller 
in size. When the resting period has 
been completed, they commence feed¬ 
ing on the lower tobacco leaves which 
rest on the ground. In most of‘this 
early feeding the beetles confine their 
eating to the lower leaf surface. In a 
short time, however, the feeding 
punctures go entirely through the leaf. 
Table III.— Length of pupal stage of 
the tobacco flea-beetle at Quincy , Fla., 
May 28 to July 21, 1922 
Date of pupation 
Date adult 
appeared 
Length 
of pupal 
stage 
May 28, p. m.. 
June 4, p. m_ 
Days 
7 
May 29, p. m_ 
June 5, p. m_ 
7 
May 30, a. m 
_ . do_ 
VA 
5'A 
5 
.Time 3, a. m _ 
June 8, p. m_ 
June 7, a. m _ 
June 12, a. m. 
Do. 
_do_ 
5 
Do_ 
June 12, p. m_ 
5 
June 8, a. m. 
_do_... 
4/4 
5 
Do.. 
June 13, a. m_ 
June 8, m_ 
_do... 
4 H 
m 
VA 
4 
Do... 
_do. ... 
June 8, p. m..... 
.do.... 
June 9, a. m 
_ do _ . _i 
Do... 
.do. _! 
4 
Do. 
June 13, p. m_! 
4J4 
4 
June 10, a. m__. 
June 14, a. m_l 
June 18, a. m_ 
June 23, a. m...... 
5 
June 19, a. m. 
June 24, a. m_ 
5 
Do__ 
June 24, p. m_ 
5J4 
4H 
4 % 
June 19, p. m.. 
June 24, a. m. 
Do. 
June 24, m_ 
Do. 
_do. .. 
iU 
Do . . 
June 25, a. m_ 
S H 
5 
June 20, a. m_ 
_do... 
Do___ 
.do... 
5 
Do_ 
_do.. 
5 
June 20, p. m. 
June 26, a. m. 
5A 
Do _ 
_ do. ... 
5H 
4J4 
June 21, a. m..r_ 
June 25, p. m_! 
Do _ 
June 26, a. m_1 
5 
June 29, a. m.. 
July 4, a. m.! 
5 
June 30, p. m_ 
July 5, p. m_ 
5 
July 2, a. m_ 
July 7, a. m_ 
5 
July 12, a. m_ 
July 16, p. m_ 
4'A 
5 
Do .. 
July 17, a. m.. 
July 12, p. m_ 
July 18, a. m_ 
5H 
5A 
5 
July 13, a. m_ 
July 18, p. m_ 
July 13, p. m. 
. do .. 
Do _ 
July 19, a. m.. 
5A 
July 14, a. m__. 
July 21, a. m. 
7 
Average of 40 records of length of pupal stage. 5.11 
The beetles remain on the lower 
leaves for three or four days and then 
gradually spread over the entire plant. 
In the case of unshaded tobacco the 
feeding is largely confined to the lower 
portion of the plant. In the case of 
shaded tobacco, however, the upper 
leaves are frequently punctured to a 
considerable extent and even the bud 
leaves are sometimes fed upon. Under 
shade conditions there seems to be little 
choice between the upper and lower 
surfaces of the leaves, although in 
high tobacco there is apparently some 
slight preference for the upper surface. 
Numerous observations have shown 
that the beetles feed at night as well as 
during the day. 
