1927] Parasites and Habits of Dianthidium pudicum Cresson 197 
of silk. The larva of number 5 started a cocoon on October 6. 
It was at first very thin and white and early had a mammillery 
point apparently closed. The following day the cocoon was 
more compact and darker. A few days later it had quite its 
normal color. 
On January 31, 1926 a nest, agreeing in all points of con- 
struction with nests of D. pudicum, was found attached to a rock 
along the railroad of East Boulder. Four female and one male 
M onodontomerus montivagus Ashmead emerged from a typical 
Dianthidium cocoon on February 20. A single hole was chewed 
through the side of the cocoon, all emerging through this open- 
ing. The male was observed to mate with two females. When 
he first alighted on the female, she vibrated her antennae very 
rapidly, after which she remained nearly motionless. The male, 
well forward on the female, continued a rather periodic raising 
and lowering of his antennae, moving first the one and then the 
other. Frequently he would raise his wings, vibrate them rapidly 
for a second, then lower them until the performance was re- 
peated again in about 20 seconds. After 3 minutes the male 
moved back and copulation was effected, lasting but a second. 
From another cocoon a wasp, Odynerus ( Stenodynerus ) n. sp. 4 
which appears to be parasitic on D. pudicum, emerged on March 
5. No other insects emerged and on May 5 the remaining two 
cocoons were opened. Each contained a wasp, nearly mature, 
but dead. These wasps were not easily determined but appeared 
to be young of E. proxima. The nest had been used a number of 
times as was evidenced by the fact that used cocoons were found, 
one within another, to the number of seven. While no bees were 
reared from the nest, the cocoons, type of nest, etc., were so 
typically those of D. pudicum that it has seemed safe to consider 
it as such. 
A nest, also agreeing with the nests of D. pudicum taken 
here, was found in the summer of 1926 by Mrs. Hicks at Uva, 
some 6 miles n,orth of Wheatland, Wyoming. One of the cocoons 
of this nest contained dead, but nearly mature parasites, M. 
montivagus. 
4 Kindly determined by Mr. S. A. Rohwer. More evidence should be ob- 
tained before definitely ascribing this wasp a parasite of D. pudicum. 
