In his recommendations for control of mites, Scott (1960) 
included the above treatment of 1 pint 25% emulsifiable concentrate of 
parathion/100 gal water applied at the rate of 1 gal/12-15 sq ft (7 1b/A). 
He also recommended the use of 1 lb 15% wettable powder/100 gal water, 
or er that used by Hyche: This would be equivalent to about 
4-5 1b/A. 
Satchell (1955) summarized the work of Weber (1953) with the 
statement that damage to earthworms was found to be greater from parathion 
"than from B.H.C. or from B.H.C. mixed with D.D.T. The effect of these 
insecticides was noticeable for 2-3 weeks." 
p-pL/ 
Offer (1950) reported that the soil fumigant D-D (dichloropropane- 
dichloropropene mixture) when applied to the soil at rates of 200-400 
1b/A had no deleterious effects upon earthworm populations. No further 
details were available. 
Miscellaneous Chemicals 
Lagrange (1946) reported that alizarin, alizarin sulfate, and 
purpurin were extremely toxic to earthworms. 
Khorana and Motiwala (1950) also described several chemicals 
that were highly toxic to earthworms. The top three in order of toxicity 
a re rs a 7-hydroxyflavone, and 6-acetyl-7-hydroxyflavone. 
DISCUSSION AND CONCLUSIONS 
Resistance of earthworms to all except very heavy doses of 
chemical was apparent in nearly all studies reviewed. It was apparent 
also that the formulation of the chemical (dust, emulsion, solution, 
etc.) influenced the effect on earthworms. In certain studies, the 
organic content of the soil was important. Several studies suggested 
that effects may appear slowly, perhaps only after many weeks or months; 
this is an important possibility that needs firm verification and 
exploration of causes. Differences in reactions of different species 
of earthworms seem probable also; few comparative data are available. 
Meaningful experimental work concerning the effects of pesticides on 
earthworms appears to be extremely difficult, because of large natural 
fluctuations in populations and because of the problems of harmonizing 
laboratory and field results. 
1/ Reference to trade name does not imply government endorsement of the 
product. 
15 
