1928] 
The Bee that Works in Stone 
69 
Furthermore, he made the interesting statement in August, 
after I had informed him that the bees were making their nests 
in the stone at White Rocks, that in 1903 he had seen some hy- 
menopterous insects in some cactus flowers near Trinidad, 
Colorado. At the time, while working on rock formations nearby, 
he found some small white bodies in the stone. These he 
thought were the pupal cases of ants. Then it was eight years 
later, in 1911, that he saw the bee, Perdita opuntice, in the cactus 
flowers at White Rocks. At that time he saw evidence of tunnels 
in the stone but did not associate them with the bee. And 
finally, in 1924, while studying the case-hardening of the stone 
at Rocky Flats Lake, 5 he saw similar tunnels in the rock. And 
so he now suggested that the bee might also be found at Trinidad 
and Rocky Flats Lake. 
With this evidence in mind, I visited these two localities in 
search of the tunnels mentioned to see if by chance they could be 
those of Perdita opuntioe. 
Near Trinidad, 225 miles south of Boulder, the Laramie 
formation, of about the same hardness as that at White Rocks, 
was found. Cactus plants, not blooming at the time, (August) 
were present in some numbers but there was no evidence at all 
of tunnels in the stone. Only an area of ten square miles was 
covered. Possibly the nests might have been present nearby. 
But the only sure way of proving the absence of the bee from 
this locality would be to diligently search the cactus flowers in 
the month of June over an extensive area. And so, up to 1928, 
no bees of this species have been officially reported from the 
Laramie formation near Trinidad, Colorado. 
In the second place, at Rocky Flats Lake, somewhat similar 
results were obtained. Only a very few cactus plants grew in the 
vicinity. However, here and there were some openings into 
the rock through which an iron wire could be pushed for a few 
inches. After chipping through the hard, granite-like surface 
of the stone to a depth of one or two inches, I came upon a 
sandstone approximately as soft as that at White Rocks. 
Through this I was surprised to find that in a few instances there 
4 Two hundred and twenty-five miles south of Boulder. 
5 Twenty miles south of Boulder. 
