_Mud-dauber wasps, building nests of radioactive mud in a waste disposal
area near an Oak Ridge, Tennessee, atomic plant, are the object of
intensive environmental radiation study. A shows radioactivity reading
from a nest. B is an enlarged view of the nest with two tiny dosimeters
in place to measure radiation. In C an ecologist inspects new nests
built in a laboratory flight cage from radioactive mud provided in pans
at the bottom. In D wasps are anesthetized, marked with tiny plastic
disks for future identification, and released._
The question, then, was why wasps of one species were using radioactive
mud while the other species seemingly discriminated against contaminated
mud. The muds appeared to be entirely alike. X-ray-diffraction studies
showed no material differences, nor were there detectable differences in
“feel”, smell, or plasticity. Radioactive isotopes in the mud included
cesium-137, cobalt-60, ruthenium-106, and zinc-65. Oak Ridge scientists
began to try to find out whether the pipe-organ wasps actually were
discriminating against muds containing all or some of these
radioisotopes or against the ionizing radiation from them. If so, how
could the wasps detect it? These investigations were continuing in 1965.
There is no answer yet.