- 23 - 
"The most suscerjti'ble creature that I know is the 
' v;ater flea' (Daphnia and Moina) , which dies rapidly in 
the most amar.ing and incredihly high dilution of the poison; 
tadpoles and mosquito larvafe were found to "be very good 
experimental subjects for recognizing the potency of different 
preparations. The first large-scale trial was made on a fruit 
plantation of Mr. Clough, at Burley, Hants, on the 23d May, 
1904. In all those trials the roots v/erc ground up with 
successive lots of water and no other ingredient added. I 
still have some of the original roots, nov; some tv;enty years 
old, and though thoy have not been regularly tested for strength, 
they still retain some active power, and a solution is ladled 
on to small seedlings when 'cut worms' are about. 
"A curious feature in derris is the localisation of the 
poison to the roots; trials of stem extract showed very slight 
activity and the leaves nil, indeed, it may be noted that they 
are attacked by some caterpillar occasionally (sp. not loiown 
to me.) " 
Kelsall, Spittall, Gorham, and Vfelkcr (54) in 1926 published the 
results of tests of derris against several insects. 
They are disposed to rcgeird derris as a contact poison only. 
Tests upon the Colorc^o potato beetle, L cptinotarsa docenlincata- Sa.y, 
v/ith derris in 4-4-40 bordeaux, derris and hydratcd lime, and derris 
alone lead to the follov/ing conclusions: Derris is effective in both 
spray and dust form; derris kills more rapidly than arscnicals; derris 
is less effective mixed v/ith hydrated lime, and still less effective 
mixed with bordeaux mixture. To get the same eventual kill, 1 pound of 
derris is apparently about equivalent to from I-I/2 to 3 pounds of 
calcium arsenate. 
A 5 or 6 year old sample of derris v;as ineffective against the 
forest tent caterpillar, Mai aco soma disstria Kb:i. , when dusted or sprayed 
upon chokccherry foliage fed upon by the caterpillars. 
Against the orchard tent caterpillar, lialacosoma a^.Tericanc^.Z It was shoim 
that (1) the derris applied to the caterpillars along with the foliage 
gave very much higher control than v/here applied to the foliage alone; 
(2) 1 pound of derris per 100 gallons of water gave an equal eventual 
control, though much more rapidly, than 2 pounds of lead arsenate; (3) 
when applied direct to the foliage but not to the caterpillars derris was 
not quite equal pound for pound to lead arsenate; (4) derris was very 
much more effective than nicotine in practical strengths. 
Derris at l/3 pound per 100 imperial gallons of water killed 100 
percent of imported currant worms, ITematus ( Ptcronidca ) ribcsii Scop. 
A dust of 98.75 parts hydrated lime and 1.25 parts derris gave 100 per- 
cent control in a heavily infested currant plantation. 
Derris at the rate of 5 pounds per 100 gallons was sprayed on 
house flies. The spray was shot at them both while they were resting 
