12 BULLETIN 1223, U. S. DEPARTMENT OF AGRICULTURE. 
of the elm are more evident than those of the scale insect, it is well 
to indicate this relationship, especially since the time of application 
of control measures often depends upon both. The tree and the 
insect awaken from hibernation at the same time. The females 
undergo their last molt while the fruit is forming on the tree. Most 
of them have attained a large size and are secreting their semi- 
cocoons when the fruit begins to fall from the tree. The semi- 
cocoons are completed by the time most of the leaves are full grown, 
and egg laying starts two or three weeks later. The second- -stage — 
larve migrate from the leaves back to the twigs and branches when — 
the tree sap becomes sluggish and the leaves begin to yellow and fall. 
NATURAL ENEMIES. 
The insect enemies of the European elm scale are very scarce and 
play but a small part in its control. The first and only record of 
the rearing of a parasite from this scale in the United States was 
in 1898 by Rh. A. Cooley (7), who reared half a dozen specimens at _ 
Concord, Mass. These have never been described, but remain under 
the manuscript name of Coccophagus gossypariae Howard. The 
writer endeavored a number of times to obtain parasites from west- 
ern material, but was unsuccessful. Either there are none in the 
West or they are so scarce that they do not figure in the control of 
this scale insect. 
The predatory enemies of the European elm scale are somewhat 
more numerous, but even they can not be considered as important 
agencies in its control. The twice-stabbed lady-beetle, CAclocorus 
bivulnerus Mulsant, is the most common enemy of the European 
elm scale. Essig (6, p. 119-120) mentions that Dr. A. J. Cook 
reported this beetle as preying upon the scale insect at San Rafael, 
Calif. The writer also has observed beetles of this species feeding 
upon the body contents of adult females. 
Both larve and beetles of the black lady-beetle, Rhizobius ven- 
tralis Erichson, ted upon this scale insect when in captivity. and in 
all probability feed upon it when free, as it is usually found abundant 
upon scale-infested trees. The common black-spotted red lady- 
beetle, Hippodamia convergens Guérin, and its variety, ambigua 
LeConte, have been found rather plentiful upon infested trees and 
probably prey upon this scale insect, yet none have been observed 
actually feeding upon it. 
The green lacewing Chrysopa californica Coquillett has also been 
reared upon the European elm scale and is found to some extent upon 
infested elms. No other insect enemies of this pest have been 
observed. 
: 
