-70- 
the holes cut in the skin '"by the grub.s./ Treatment should begin ebout 
December 20-25 end ; should ''be- repeated et-25- 30-day intervals until 
no more grubs anp ear on the becks o.f the animals. 
' Otitidae 
Euxeste stigmeties Loe" 
B. A. App in 1936, in e type-ri-tten report to the Division of 
Ce,reel and Forage Insect Investigations, Bureau of Entomology and 
Plant Quarantine, United States Department of Agriculture, stated that 
e derris-telc dust containing 1 percent of rotenone shored a control 
of 3.9 percent of. maggot's, as compered ^ith 19 percent hy the leed 
er senate dust. 
Psilidae 
Psile rosee (P.) , "the carrot rust fly 
Smith and Wadsworth ( 255 ) in 1921 tested insecticides egeinst 
the carrot rust fly. Four explications of e ponder composed of soot 
end derris et the rate of 1 ounce of derris plus 2 ounces of scot 
per souare yard resulted in 95 percent of clem carrots. The control 
plot yielded only 20 percent of carrots free froip infestation. This 
derris mixture gave the "best control of any of tne materials tried. 
K. M. Smith ( 254 ) in 1925 reported that tests were made '--ith 
various insecticides. A mixture of 1 ounce, of derris' '"ith 2 ounces 
of soot per square y?rd did not give results promising enough to 
justify further trials '•'ith it. 
- Kelsall et el. ( 159 ) in 1926 reported thr-t derris in either 
dust or liquid form gave a considerable measure of control, the 
material being ep-olied to the soil surface about the time egg laying 
wes in progress. The control tvas apparently eccorroenied "by plant 
stimulation also. 
The Massachusetts Agricultural Experiment Station ( 19? ) in 1929 
stated that derris products had <?iven very enpouraging results against 
the first generation in 1927 and 192G but '-ere ineffective against 
the second generation. 
Glasgow ( 114 ) and Glasgow and Gaines (116) in 1929 reported that 
five applications of derris dust et weekly intcrvels were ineffective 
in combeting immature steges in soil. Mercurous chloride ras 100 
percent effective. 
^Thitcomb' ( 316 ) in 1929 reported promisin"? results **ith derris 
compounds for control in Massachusetts. In the laboratory all flies 
confined with wotted carrots dusted with pondered derris root died 
