14 BULLETIN 1357, U. S. DEPARTMENT OF AGRICULTURE 
473) says: “No male adults have been seen at any time in our three 
years of observation with this species.” Males are known to occur — 
out of doors, and these observations indicate possible thelyotoky in 
the greenhouse forms. Whether or not they are fertilized, it is an 
outstanding fact that practically all the eggs in the masses observed 
in greenhouses have hatched. | 
Although 25 adults which emerged on the same day were removed 
from the rearing cage and confined singly, so that the only possible 
access to males was before they were isolated, three of them deposited 
eggs. In another case eggs were obtained from two reared adults 
which were segregated immediately after emergence. In this con- 
nection Peterson (23, p. 473) observes that the ovaries of newly 
emerged adults are in an immature condition and do not develop to — 
any extent until the adult has consumed some food. At first the © 
---------- Temperaiure . 
80 6 EEE EEE EEE EEE EEE EE] number of ogee ia |2e 
Soh Besos aeRO 
ep fp ee te 
GEER BERS eee ee Reese gaia BRE >| 
fe ie SE eS 
oe | EES evi a] a ea aN EEREBREECS SSS 
<= a at Fa aE EW PF 0 EBRS SS a. 
= Ss NEG See aH e SER eR eee e wee eee REnEE TE. 
refed 0 EF Se Ss aehstih eh es 
® ; ER aeem ere HBA | 1 ttt leole 
° 3 Piatt ssa 72 
S 70 B Se 76 
ul 6 74 
> 60 72 
5 55 70 g 
o 50 68 
E 45 
Z 40 
FARES SP eeeey 
ESR REE! AR BRA! Pee EP SEWERS ih WEB 
Let tT TT tT eT TACT TTT NTT TT 
eel eINGIETSTINZ INTE ENE IE TV ANI So NS eee ty 
PM AM pM 
a a 
L246 810 i2246810l2 246 610/224 68610 l2 246 8 OlAa246 8101224 6 8 10, 
July I July l2 July I3- July 14 
Fig. 6.—Egg ps lanes by strawberry rootworm adults. Records every two hours from 
uly 11 to 14, inclusive, Doylestown, Pa., 1922 
abdomen is very soft and does not become fuil and hardened until 
seven days after emergence, so that, although possible, it is doubtful 
whether mating takes place while the female is in this undeveloped 
state. Furthermore, as is shown in Table 7, no eggs were laid by 
reared individuals until 19 days after emergence, or 18 days after 
they were isolated. From the foregoing circumstantial evidence it 
would appear that parthenogenesis is a possible feature of the biol- 
ogy of this insect under greenhouse conditions. 
OVIPOSITION 
Oviposition may take place, at least to a limited extent, through- 
out the year, since the eggs have been obtained from caged beetles 
in each month. In the greenhouse, however, most of the eggs were 
laid in the spring and early summer months. The earliest records 
of the finding of eggs in the rose houses are March 9, 1920, March 
1, 1921, and March 14, 1922, and after these dates eggs could be 
