260 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
feeding on locust eggs has been confirmed by obtaining tliem from tbe 
egg-masses of several other species, and the fact that they have a similar 
habit on the Pacific coast is shown by the frequent presence of the 
coarctato larva among the eggs of the destructive locust of California 
(Camnula pdhicUla Scudd 
One experience with them is worthy of record in this connection, i. e., 
the retarded development that is often manifest in certain individuals, 
as stated in a recent number of the American Entomologist: 
"In the month of October, 1877, we hatched a number of triungulius 
from the same batch of eggs laid by a female of the Striped Blister- 
beetle (Epicauta vittata), and fed them on the eggs of the Differential 
Locust ( Caloptenus differentialis). Several of the resulting beetles issued 
the following summer; three of them passed a second winter in the 
coarctate larva state, and issued as beetles the second summer; while 
one remained unchanged during this second summer of 187!>. We ex- 
amined it from month to month, always finding it healthy, but began to 
fear, as the present summer approached, that it must have been injured 
and was really dead. It was unchanged on the 3d of May of the present 
year, but on Looking at it again on the 15th of June, we were gratified 
to find that it had left its rigid skin and presented itself in the form of 
the final or third larva. It had transformed to the true pupa on the 1st 
of July, and would undoubtedly have given out the beetle two weeks 
later had we not preferred to preserve it in the pupa state for our 
cabinet. 
"In this case the individual, though submitted to exactly the same 
conditions as the other specimens, which had simultaneously hatched 
with it — but which went through all their transformations within either 
one or two years — remained dormant for nearly three years, with their 
repeated changes of season and temperature. With the exception of 
the first winter, when it was kept indoors without freezing and when 
development should have been presumably hastened, the specimen was 
kept in a tin box buried the proper distance beneath the ground out of 
doors, so as to be as nearly as possible under natural conditions." 
This irregularity in the development of individuals is noticeable in 
many insects that are parasitic and whose mode of life is precarious. 
In the case of our blister-beetles, depending as they do on locust eggs, 
and especially in the case of those which feed particularly on the eggs 
of migratory species, it is not difficult to perceive how this trait may 
prove serviceable to the species possessing it. Migratory locusts occur 
in immense numbers in some particular part of the country at irregu- 
lar intervals, and there are periods or years of absolute immunity from 
their presence in the same regions. The young blister-beetles that hatch 
the year following the advent of the locusts in immense numbers may 
frequently find few or no locust eggs upon which to prey, and the great 
bulk of them would, as a consequence, perish ; while the young from such 
6 ' A (Edipoda atrox of our First Report. 
