August, ’18] 
PARKER: CHLOROPISCA GLABRA HABITS 
379 
found but from this time on, the number of puparia rapidly increased 
until September 21, when practically nothing but this stage could be 
found. None of the puparia obtained in the breeding boxes during 
August emerged until the following spring. 
All of our studies carried on in 1916 indicate that at Bozeman C. 
glabra is single brooded. However, in repeating part of the rearing 
work in 1917 it was found that in that year at least, a partial second 
brood occurred. 
On August 8 and 10 fifty newly transformed puparia were collected 
from about the roots of Chenopodium growing in a compost heap. 
By August 28 forty-five adults had emerged. 
Twenty-six puparia were also collected on August 10 from about 
the roots of Chenopodium growing in ordinary soil. From these three 
adults emerged September 2. The remaining puparia appear to be 
perfectly normal and are being held in an outdoor rearing cage. 
Fifty large maggots were collected on August 11, isolated in rearing 
boxes and each supplied daily with 20 root lice. At the end of seven 
days 42 had transformed to puparia and 8 had died. By September 
2 five adults had emerged; the remaining puparia all seem to be alive 
and apparently will pass the winter in this stage as did all the indi¬ 
viduals reared in 1916. 
With the above exceptions, C. glabra is considered as single brooded 
at Bozeman. The main reasons in support of this statement are as 
follows: 
1. Adults continue in about the same numbers throughout the sum¬ 
mer, disappearing gradually during September. 
2. Larvae never appear in abundance until August and always dimin¬ 
ish rapidly during September. 
3. Puparia do not reach their maximum abundance until September. 
4. Puparia collected at any time during one season seldom emerge 
until the following spring. 
5. Females which emerge in the fall have the ova only slightly de¬ 
veloped. Considering that females which emerge in May do not lay 
eggs until July it does not seem probable that the few adults which 
may emerge about September 1 could reproduce before being killed by 
the fall frosts. 
In warmer sections of the country, and at lower altitudes it is quite 
probable that C. glabra is double brooded. This is indicated by 
Coquillett's rearing notes already referred to. 
Economic Importance 
C. glabra in Montana is by far the most effective insect enemy of the 
sugar-beet root louse (Pemphigus betoe), which in turn is the worst pest 
with which the sugar-beet growers of Montana have to contend. 
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