- 7 _ 
each yo\ing plant at the mto of a cigarette tin full to 4 plants, 
morning and evening. This was continued for 15 days, until the plants 
v/erc sijiff iciently established to "be past all danger, v/hich is only 
present during the first stage of their existence, when the stem 
is quite tender. Only 16 seeds failed to germinate, and of the 1,040 
plants that came up, ndt one has since died. And today the plot is 
showing the most vigorous growth, a living testimony to the potency 
of the tuba-root ad a plant -insect killer." 
Lloyd (59) in 1920 reported tests of preparations of tuba root (derris) 
against larvae of the glasshouse tomato moth, Polia oleracea L. , (l) as a 
dry dust, alone and in dilution x^rith powdered earth; (2) v;ith saponin in water 
suspensions, at various strengths from 0.25 percent to 10 percent by weight 
of the powdered root, nixed and strained th-ro\igh muelin; (3) with saponin in 
water suspensions of an alcoholic extract (six times the strength of the 
powdered root), at various strengths from 0.08 percent to 2 percent by weight. 
These derris preparations were made by Tattersf ield. 
Tomato plants in pots were dusted or sprayed with these and infested 
with larvae collected in nurseries. The dusting was unsatisfactory, as it 
made the plants dirty and encouraged the growth of molds. The water 
suspensions of the powdered root killed the larvae at a lO-pcrccnt strength, 
but a 5-percent strength failed to do so within a reasonable time. These 
strong mixtures also dirtied the foliage. Suspensions of the alcholic 
extract proved very satisfactory sprays on an experimental scale. A 
series of 18 experiments sho\ired that 1 part of this substance by weight 
in 1,000 parts of water is a sufficiently potent spray. A plant sprayed 
with this i-zas infested with 12 half-grovm larvae which were confined to one 
leaf by means of a sleeve. Ty;o days later 7 of these were dead, and 8 
days after they were put on they were all dead. Ten more half-grown larvae 
were then placed on another leaf, ^nd 10 days later all these were dead. 
The spray therefore remained potent for 20 days. The foliage of the 
plant was not damaged, and the fruit set normally. This plant at the end 
of the experiment was photographed with a control plant of the same age 
which, v/ithout spraying, was infested v.'ith 10 half-grovm larvae at the 
time the second lot was released on the sprayed plant. They completely 
ate a leaf each day and had destroyed the plant by the time those on the 
protected one were all dead. Similar experiments were carried out with 
strengths of 5, 2-l/2, 1-2/3, l-l/4, and 5/8 po\md of the alcoholic 
extract in 100 iutperial gallons of \-/atcr, respectively, and each plant 
was infested with 22 larvae as described above. The results varied 
little from those detailed, except that with the weakest strength the 
death rate v/as somewhat slov/er. Hone of the plants were damaged, and the 
substance appears to be safe to use, but no large-scale experiments were 
carried out. 
riippance (32) in 1920 suggested tuba-root (derris) povrder for 
combating various small beetles attacking palms in the Straits Settlements, 
also for use against the larvae of the large coconut butterfly, Amathusia 
phidippua L. , and the larvae of Erionota thrax L. 
