At Oak Ridge National Laboratory, Tennessee, it was discovered in 1964
that two kinds of mud-dauber wasps were building their mud nests in
equipment, cabinets, and electronic gear in the vicinity of a field
station on the Oak Ridge reservation.
Some nests, investigation disclosed, were built of radioactive mud. It
seemed obvious that the wasps were obtaining mud from radioactive waste
pits or from the White Oak Lake bed, which is the site of a former
40-acre lake used for 12 years as a detention pool for radioactive
wastes.[18]
The mud daubers were carrying mud as far as 650 feet from the
contaminated sources. Almost 90% of 112 nests built by the yellow-legged
mud-dauber species were radioactive, and the mud was delivering to the
wasp eggs each hour a dose of penetrating radiation equal to that
received by a man from all natural sources over a period of many years.
The development presented no human health problems, but further
observation revealed a fascinating circumstance.
At the same time, another variety of wasp, the pipe-organ mud dauber,
was building nests only of _non_radioactive mud. Of 150 pipe-organ wasp
nests examined, none was radioactive. The nests were found in similar
locations, and it was apparent that the same sources of nest materials
were available to both species.