THE PEA APHIS WITH KELATIOX TO EOKA(JE CKOPS. 
51 
at any tinio except in fall or early winter, and crnnatic conditions no 
don})t have some direct or indinu't influence. 
In our experiments oviparous fcunales were produced much oftener 
than males, prohahly accountable from the fact that in(Hvi(hial males 
may fertilize several females. Tlie oviparous femah^s luv invariably 
wingless: hut we have found hoth Axinged and wingless males, the 
latter in only a few instances in 1911. In the field Mr. ITyslop also 
observed the A\'ingless male. In the case recorded by him a winged 
and ^\'iIlgless male were attempting to mate with the same female. 
To our knowledge these are the only two records of the occurrence 
of ^\-ingless males in America. 
Mordwilko (10) has observed ^^^ngless males in Russia, and in his 
^\Ti tings has described tliis form. 
Copulation takes place soon after the individuals reach maturity, 
and egg la\'ing commences shortly thereafter. Eggs are laid on the 
stems and 'leaves of red clover, according to our observations in 
Indiana; but Mr. Hyslop, in his observations w^th this species on 
alfalfa, mentioned above, found eggs only on the leaves of aKaKa 
and in no case on the stems, petioles, or axils. We have no records 
of the sexual forms being produced or eggs being laid on any plants 
other than red clover and alfalfa. However, MordAvilko (10) has 
observed the sexual forms on Medicago falcata, Laihyrus latifolius, 
and L. angustifolius , and Theobald (11) found them on the flat pea 
{LatJiyrus sylvestris). 
FECUNDITY OF OVIPAROUS FEMALES. 
Actual counts of the number of eggs laid by individuals were not 
made, but dissections of 12 unfertilized females several weeks after 
maturity showed that they were capable of laymg an average of 25 
eggs. (See Table VII.) These counts indicate that the fecundity 
of oviparous females of pisi is t^\dce that of the average aphidid. 
Table VII. — Number of eggs of Mficrosiphuin pisi. 
Date. 
Number of eggs 
laid previous to 
date of dissec- 
tion. 
Number of 
apparently 
fully devel- 
oped epps 
found in 
body. 
Number of 
immature 
esrps in 
body. 
Total num- 
ber of eggs 
exclusive 
of undevel- 
oped ones. 
Dec. 6,1912 
Do 
1 or 2 
27 
24 
IS 
25 
25 
19 
IS 
25 
21 
17 
2(> 
30 
2-f 
28 or 29 
25 or 2G 
20 
27 
27 
21 
20 
27 
23 
19 
28 
32 
1 or 2 
Several 
Dec. 10. 191'- 
Do 
Avg. of 2 per 9 - . . 
do 
Do 
do 
Do 
do 
Do 
do 
Do 
do 
Do 
do 
Do 
do 
Jan. 4,1913 
Do 
•) 
o 
Avernffi 
23 
24. S-f 
1 
