68 
been such a nuisance that the men objected to handling the crop. After 
cutting, the clover never revived. In neighboring fields there were 
many bare spots where the aphid had killed the clover locally, and in 
the growing clover were many centers of new infestation, due doubt- 
less to migrant winged females. All the clover in that part of the 
county was more or less injured ; not only old clover, but also the first- 
year growth. Returning to the same region the following summer, to 
see the consequences of the injury, I did not stay long, for it was hard 
to find a field of clover anywhere. The farmers reported that the 
clover had been "winter-killed," to their surprise, since the winter had 
not been a severe one and the clover had often survived worse winters. 
The failure of the clover had discouraged almost all of them from 
sowing a new crop. My personal opinion was that the "winter-killing" 
would not have occurred had not the plants been weakened previously 
by the aphid. Clover is undoubtedly injured by certain winter influ- 
ences, especially by being "heaved" out of the ground by frost, but 
there must be taken into consideration also the inability of the plant to 
face the winter when it has been ravaged by such insects as the aphid 
or the root-borer. 
Only at rare intervals has there been a bad outbreak of this spe- 
cies. In England, according to Kirby and Spence, the havoc wrought 
by this aphid in 1810 was remarkable for its suddenness. Equally un- 
anticipated was the outbreak of 1899 in some of the Atlantic states 
and in Canada. In 1900 the devastation continued in places where the 
previous injury had been worst, and a new outbreak occurred in Wis- 
consin. Since then no reports of serious damage have been published, 
but in Illinois this aphid was locally injurious in 1903, as just de- 
scribed, and has menaced the red clover every year from 1903 up to 
the present. Heavy rains subdue the louse almost every year. 
Description. — The clover-louse is noticeably larger than any of 
the other aphids that frequent the field, the largest females being 6 mm. 
from tip to tip. The green color of the louse matches that of its food 
plant. The legs are conspicuously long, and the tarsi, distal ends of 
the tibiae and femora, as well as the tips of the -cornicles, are fuscous. 
The antennae are darker at the joints, with the terminal filament fus- 
cous. The eyes are red and prominent. With this general statement 
we may pass to a more detailed description of the species. 
The generic term Nectarophora is antedated by Macrosiphutn 
(Pergande, Bull. 44, Div. Ent., U. S. Dept. Agr., pp. 13, 14). 
With the other species of its genus, M. pisi has the front of the 
head concave, with a large pair of tubercles supporting the antennae. 
The antennae, legs, cornicles, and abdominal stylus are exceptionally 
long in this genus as compared with other genera of aphids. The wings 
are large, the third discoidal vein has two forks, and the stigma is 
elongate-lanceolate. The terminal portion of the sixth antennal seg- 
ment is very long and bristlelike. Most of the species of Macrosiphiim 
are large and frequent herbage. 
On the basis of Sanderson's studies we are obliged to regard this 
aphid (the A'^. destructor of Johnson) as the common M. pisi, of Eu- 
rope, described long ago by Kaltenbach. 
