14 BULLETIN 902, U. S. DEPARTMENT OF AGRICULTURE. 
proved. The larva spins a light gray cocoon in which it transforms 
to pupa, and the adult parasite emerges through a small hole which 
it eats out of the end of the cocoon. The greatest percentage of 
parasitized beetles observed at any one time was 16. 
Just what influence this parasite has in holding the beetles in 
check has not been determined. It is sometimes an important 
enemy of the related striped cabbage flea-beetle (Phyllotreta vittata 
Fab.) 
A NEMATODE PARASITE. 
Nematodes infest the adult beetles. As generally observed these 
nematodes were young and small, about 1/40 of an inch in length. 
From 200 to 500 were counted in a single beetle. In several instances 
adult female nematodes were observed which had the body sack filled 
with newly developed. nematode young that had not yet escaped. 
As nearly as could be determined the nematodes were not confined 
to the digestive tract but appeared to be in the body cavity. In a 
number of cases eggs laid by the beetles were found to be infested 
externally with the nematodes. The eggs had an unhealthy ap- 
pearance and in no instance were infested eggs observed to hatch. 
Just what effect the nematodes have on the beetles would be an 
interesting problem to work out. 
A GREGARINE PARASITE (GREGARINA). 
Gregarine worms 9 occur in the intestines of the adult beetles, 
infestation averaging as high as 40 to 50 per cent, but it could not be 
determined whether these had any detrimental effect upon the host. 
They occur in almost all forms of insects and as far as known have no 
serious effect on them. 
BIRD ENEMIES. 
Mr. W. L. McAtee of the Biological Survey reports having found 
the western cabbage flea-beetle in the stomachs of three species of 
birds, and other beetles of the same genus in the stomachs of 12 kinds 
of birds. The land birds include among enemies of these beetles the 
common and Texas nighthawks (CJiordeiles virginianus and C. 
acutipennis texensis), white-throated swift (Aeronautes melanoleucus) , 
horned lark (Otocoris alpestris), starling (Sturnus vulgaris), song 
sparrow ( Melospiza melodia) , chipping sparrow (Spizella passerina), 
tree swallow (Iridoprocne hicolor), and marsh wren (Telmatodytes 
palustris) . 
CONTROL MEASURES. 
• EXPERIMENTS WITH INSECTICIDES AND DETERRENTS. 
Ten experiments with arsenicals and one with nicotine sulphate 
were made in Otero County, Colo., by the junior author, and may be 
summarized as follows: 
9 Identified by the junior author. 
