FOREWORD 
Production of synthetic organic pesticides in the United 
States exceeded 700 million pounds in 1962. Persistent types made 
up significant proportions. By excluding exports and accounting for 
previous year's stocks, Shepard et al. (1963) estimated the year's 
domestic "disappearance" of DDT at more than 67 million pounds and 
of the aldrin-toxaphene group at more than 82 million pounds, 
Several studies have shown that pesticides of persistent 
types can accumulate in the bodies of animals to such an extent that 
the contaminated animals cause fatal poisoning of other animals that 
feed upon them, This concentration of pesticides through the food 
chain has been shown especially well in lakes. There a chemical 
applied at the rate of a fraction of 1 part per million may be 
concentrated in small organisms and be further concentrated in the 
fish that prey on these organisms. The fish may come to contain 
hundreds or even thousands of parts per million of the chemical. 
Birds that eat such fish may be killed in considerable numbers. 
Concentration of pesticides by animals in terrestrial 
situations has not been demonstrated so thoroughly, but Barker (1958) 
found that living earthworms from areas treated for control of Dutch 
elm disease contained DDT in amounts that could be fatal to robins that 
fed the worms. Other workers have attributed mass mortality of 
robins to this cause. Work of the Fish and Wildlife Service (unpublished) 
has shown that earthworms contaminated with heptachlor at levels often 
found in treated areas are fatal to woodcock that feed upon them for a 
few weeks. And we know that animals that receive less than a fatal 
amount of pesticide may suffer impaired reproduction. This is one of 
the factors that has been suggested as responsible for poor reproduction 
by bald eagles in the eastern United States.. 
The Fish and Wildlife Service has been especially interested 
in earthworms because of their importance as food for woodcock, robins, 
and other animals, and because reports from workers trying to control 
earthworms indicated that worms were surprisingly resistant to chemicals 
and thus were very likely to become dangerous carriers. As one 
approach to this problem, a survey of literature was made to learn what 
was known of the susceptibility or resistance of earthworms to pesticides 
Since the results of the survey are of interest to workers in several 
fields, it was thought best to present them in significant detail in the 
form of a review paper. 
