MAY 31 1973, JUN 1 1973; Wasps Join The Fight; Les Eklund, right, an entomologist with the State Agr

MAY 31 1973, JUN 1 1973; Wasps Join The Fight; Les Eklund, right, an entomologist with the State Agriculture Department, releases a batch of wasps into a tree in a northeast Denver park Thursday, beginning an experiment aimed at learning if wasps-native to France-can survive in Colorado's climate. Five cardboard containers, each holding 500 of the insects, above, were placed in the foliage of five trees, where the wasp hopefully will lay eggs on the larva of disease- carrying bark beetles. The wasp offspring should consume the beetle larva, helping combat the affliction that has killed thousands of the state's elms. Another 2,500 wasps were released in Fort Collins, Colo. The wasps are harmless to humans. Trees in Grand Junction, Colo., and Pueblo, Colo., will be given the same treatment later this summer. The wasps were bred during the winter at the state insectory at Palisade.; (Photo By Bill Wunsch/The Denver Post via Getty Images)