200 Trans. Acad. Sci. of St. Louis 
any one time, and most of the time not even that many. 
Since the shedding-skins of the silver-winged parasite, 
A. tigrina, were often to be seen adhering to the wood 
near the holes, it seemed probable that Monobia suf- 
fered its share of the ravages of this pest. 
Their season was long; the first appeared about June 
26th, 1917, and on October 3, two were seen, still cling- 
ing to the woodwork over the bank, stunned and half 
dead with the cold, while a third one was seen to enter 
its tunnel. In 1918, they appeared in decreased num- 
bers, and by 1920, only three could be found. I sus- 
pected that A, tigrina was more responsible than any 
other factor for their elimination. 
The grass-carrying wasp, Chlorion (Isodontia) au- 
ripes Fernald. [S. A. Rohwer]. 
This wasp, a very conspicuous if not numerous mem- 
ber of the unit, occupied the old tunnels of the carpenter 
bee, and occasionally she used the old burrows which had 
been made in the clay bank by the mining bees. It 1s 
very easy to tell just where this wasp mother has her 
nest, for instead of plugging the opening with mud or 
otherwise concealing it, she stuffs the aperture with 
grass, drawing each strand in by its middle, so that a 
broom-like tuft protrudes prominently, thus revealing 
at once to an experienced eye the location of her nest. 
This insect occurred in very modest numbers; no more 
than three or four individuals were at work at any one 
time. In 1920, neither the wasps nor their nests were 
to be found there. There was evidence to lead us to 
think that the silver-winged parasite had played havoe 
with these wasps, the same as with the other occupants © 
of the carpenter bee galleries. 
