g2 INJURIOUS INSECTS OF I909 AND IQIO. 
out. Some were used as check plots, and some were surrounded by 
various barriers to keep out the larvae. The plots contained the 
following food plans: Hemp, Peony, Dahlia, Corn, Potatoes, To- 
matoes, Golden Glow, Asters, Tiger Lilies, Hollyhocks, Giant Bur 
Elder, Giant Ragweed, Burdock, Daisies and Sunflowers. Amongst 
the barriers tried were strips of lime six inches wide thrown 
around the entire plot; ditches dug with perpendicular faces next to 
the plots all the way round; tarred paper strips 
surrounding the plots, laid flat on the ground, 
six inches wide, covered with tangle-foot ; ap ban eS 
galvanized iron strips stuck in the ground yi, 44 pupa ot P. nitela. 
edgewise, alone, and painted with tar, painted Orisinal. 
with tangle-foot ; shingles stuck in the ground 
endwise and overlapping one another, completely surrounding the 
plots alone, and painted with tar, with tangle-foot; plots also com- 
pletely surrounded by strips of creosoted sawdust, six inches wide; 
one-eighth inch boards edgewise, alone, and painted with tar and 
tangle-foot. 
Larvae were placed amongst these plots and were allowed to 
crawl around, and were watched; and it was found that only 
those barriers which had a coating of tangle-foot in some form were 
successful in stopping them. It was also found that only barriers 
which extended about three inches above the ground kept the tan- 
gle-foot free enough from dirt for any length of time to be of 
value. The shingles had a tendency to get out of place badly, leav- 
ing cracks between them; and it was found that, everything con- 
sidered, the best barrier was one made of thin boards about five 
inches wide, about one-eighth of an inch thick, placed in the ground 
edgewise, and smeared with tangle-foot on the side away from the 
plot. Plots of ground were also surrounded 
with these barriers, and the painting with 
tanglefoot, tar, etc., reversed, being placed on co Se ee 
the inside, and the caterpillars mae on the cae 
inside, to see if they could get out of the plot ee rebin OL ae ae 
over the barriers; and here, too, the only 
thing which was capable of stopping them 
satisfactorily was a complete barrier like the thin board smeared 
with tangle-foot. It was noticeable that the caterpillars which were 
placed among the plots in the insectary garden, and their move- 
ments watched for some time, would, when within about two feet 
of their favorite food-plants, show a very strong determination to go 
