61 
inclosed. A tablespoonftil serves for ordinary tubs. This treatment 
does not injure the plants and if the tub fits tightly to the ground 
the vapor of the bisulphid is retained and the lice will all be killed. 
This remedy is much used by growers of melons and cucumbers who 
watch their vines carefully, removing and destroying affected plants 
and fumigating those which can be saved. 
THE BEET APHIS. 
[Pemphigus hetse Doane.) 
This insect is a root-louse and comparatively new as a pest. Atten- 
tion was first drawn to it in 1896, and for three or four years after- 
wards it did considerable injury to sugar beet in Washington.^' We 
do not know its full life history nor its distribution, but it occurs 
also in Oregon and probably in California. In Oregon a thousand 
tons or more of beets were ruined in a year in a single valley. This 
insect is one of many which may be seemingly harmless up to a certain 
point, but, with a changed environment, become of more importance 
economically. 
The smaller rootlets of beets are first attacked and, when the aphis 
occurs in large numbers, they are soon destroyed. The loss of these 
so weakens the plant that it is not able to withstand further attack, 
and, as a result, the leaves wither and the beet shrivels and becomes 
spongy. W^ild yarrow {Achillea lanulosa) appears to be a normal host 
plant, and when its roots are examined in localities where the insect 
abounds, they will frequently be found covered with the white woolly 
excretion of the insect, while the louse itself is feeding on the smaller 
rootlets. This species also lives on knotweed or door-mat weed {Poly- 
gonum aviculare)^ on grasses, and some other plants. It is likely to 
increase its range, but this may be a matter of slow accomplishment, 
unless it is introduced from one locality to another on beets in 
shipment. 
METHODS OF CONTROL. 
Owing to the large acreage which is planted in sugar beet in many 
portions of our country, it does not seem probable that we can treat 
satisfactorily an insect like this root-louse, which feeds underground, 
by means of insecticides. Kerosene emulsion and bisulphid of carbon 
will no doubt kill it, but the expense would be excessive were either 
used on a large scale. Nor can we hope entirely to eradicate the pest 
when it has taken up quarters in our fields by means of cultural meth- 
ods. Additional observations on its life history and experiments look- 
«Cordies: Sugar Beet Gazette for November, 1899; Doane: Bui. 42, Wash. State 
Agr. Expt. Sta., 1900, pp. 3-11. 
