Calcium Arsenate 
Escritt (1955) found that 300 - 450 1b/A (1 - 1.5 oz/sq yd) 
gave good earthworm control but sometimes damaged the turf. He found 
no correlation of variation in turf damage with soil texture, pH, 
phosphates, potash, turf type, season, or weather. He reported good 
earthworm control for as much as 6 years. 
Lead Arsenate 
Escritt (1955) mentioned, without further detail, that lead 
arsenate applied at 450 - 600 1b/A (1.5 - 2 oz/sq yd) gave effective 
earthworm control for as much as 5 years, or more. 
Polivka (1951) obtained different results in his studies 
made on sandy soil in Ohio. Lead arsenate (without diluent) was broad- 
cast by hand on sample plots at rates from 218 - 653 tb/A (5 - 15 1b/ 
1,000 sq ft). Treatments were made in September. All plots were examined 
for earthworms the following May (8 months after treatment) and again a 
year later (20 months after treatment). At neither time were earthworm 
population changes significantly different from those in control plots. 
In a second experiment, Polivka (1951) applied lead arsenate 
to sandy soil at a rate of 500 1b/A; treatments were made in October. 
Five years later there was no significant difference between earthworm 
populations on these treated plots and those on untreated plots. 
“ee Polivka (1953) reported variable results in further experi- 
ments with earthworms and lead arsenate. On one series of plots 
treated with 435 1b/A of lead arsenate in April 1948, and examined in 
October 1951, mean numbers of earthworms per square foot did not differ 
on treated and untreated plots. On another series of plots, in contrast, 
the same application rate, 435 1b/A, reduced mean populations to zero, 
and the populations did not recover even after 5 and 6 years. Ina 
final experiment, lead arsenate was applied to sample plots at rates of 
436, 871, and 1307 1b/A (10, 20, 30 1b/1,000 sq ft) in October 1947. 
Four years later, only the plots that received the highest treatment 
showed significantly lowered populations. After 5 years, however, all 
treated plots had mean populations significantly lower than those of 
untreated plots. Soil differences may have influenced the variability. 
More samples of earthworms taken at short intervals would have helped in 
interpretation of results. 
ORGANIC CHEMICALS 
Aldrin’ 
Aldrin showed no significant effects on earthworms in an 
experiment reported by Edwards and Dennis (1960). 
5 
