- 2a - 
The authors concliided: 
"Tests of the application of washes, powders, and ointments 
to the iDaclcs of the cattle and also the injection of substances 
into the cysts containing the larvae shov; that each of these 
nethods of treatment is effective if certain materials are used. 
Among the most effective should "be i.;entioned: Lerris used as a 
wash, as an ointment, or as a powder; iodoform used as an oint:.ient; 
p^'rethrjmi applied as an ointment; benzol and carbon tetrachloride 
injected into tho grub cj-sts; fine tobacco aoplied in powder form 
and nicotine dust applied dry." 
Carlos (17) in 19/?6 reported that dcrris vs a contact or external 
poison, vdth or without the use of soap as a spreading agent, had been- 
found offcctivc against aphic's in as low a riilrtion as 1 poum^ of root 
to 400 inpcrial gallons of water, which rcnrcscnts a proportion of 0.025 
percent. As a stomach or internal poison, stronger solutions arc required, 
the lov.'Ost being 1 pound to 12C: inporial gallons of v/atcr, or 0.08 percent, 
Catcr;9ill..rs, aphids, psylla, and red spiders arc some of the chief insect 
pests v/iiich can be easily exterminated by the application of insecticides 
conto-inin;'-: dcrris or its products. One interesting property of dcrris as 
a killing agent is that the effect lasts for a considerable time. Leo.vcs 
when sprayed with a solution containing dorris preparations will remain 
poisonous to insects for Taoxiy days. 
Castillo (18) in 1926 reported the results of studies on the 
insecticidal properties of three species of derris growing in the 
Philippines, namely, D. polyanth a Perk. . D. philippinensis Herr. , and D, 
elliptica (Roxb. ) Benth. The roots -vere cut into thin transverse slices 
and dried in an oven at 40° C. until the weight remained fairly constant. 
The dried material was then comminuted in a mortar and the powdering 
finally coEipleted in a meat grinder. The fine powder was separated from 
the fibers hi'- sifting through fine-mo shed cloth. 
In the comparative sti-'.dies of tho effect of various concentrations, 
Derri z philippinrn sis ^"as used on account of its being relatively more 
abundant, hence more easily procurable, than the others. Insects of tv/o 
types of habitat wore used, najncly, an aquatic insect, the mosquito 
larvae, and an aerial insect, Ai.')hi s medica-gini s Koch, Oi\ mosquito larvae 
the r.-iost effective concentrations of D. phil^imincnsis in bringing about 
the bijjhcst percentage of deaths in the quickest time was 3:1,000. 
Solutions which v/ere either more dilute or more concentrated than 3:^)00 
were found less effective. Concentrations of 1:1,000 killed 19 percent 
of the larvae in 5 days; lower concentrations showed no effect at all. 
A concentration of 3:1,000 or higher retained its toxicity against mosqiiito 
larvae for 13 to 16 days. Concentrations higher than 3:1,000 presumably 
becai.ie effective later, as a result of deterioration and consequent lowering 
of the percentage of toxic principles present. The concentration of D, 
philippinensis which brought about the largest number of deaths of aphids 
was much higher than that required for mosquito larvae, nhiacly 4:1,000, 
The lo'jost concentration of D, philippinensi s used, 0.5:1,000, caused a 
noticeable percentage of mortality among aphids, as compared with the 
control. 
