- 2 - 
There are two species of hornworms that attack tomatoes--the tomato horn- 
worm (Protoparce qu in quemac u 1 ata (Haw.)) and the tobacco hornworm (P. sexta 
( Jo hanTJJ," which" are widely dis tribute d over this country. In certain sec- 
tions they are, unless controlled, very destructive. They feed on the foliage 
of the plant, first attacking the leaves, oftentimes stripping the plants to 
the point where only the main stalk or stems remain, 
(r Control ■•• 
The problem of controlling these several pests when they occur in the 
same field is somewhat involved, as a remedy for one may not be suitable for 
the other. In California the tomat* fields may be infested at some period 
during the same season with the tomato fruitworm, the tomato pinworm, horn- 
worms, the tomato russet mite, rutworms, and the beet armyworm. 
In consideration of these factors, the determination of the proper remedy 
or remedies will depend on the kind of insects present in the field.. The 
discussion on the control of these several pests and their joint control 
follows. 
Tomato Fruitworm Control 
Cryolite and calcium' arsenate- dusts arrd a bait prepared by mixing corn 
meal with cryolite are all about equal in effectiveness for the control of the 
fruitworm. The choice between these materials is discussed in more-detail in 
the following paragraphs, 
Cryo 1 jte . — Extensive experiments have demonstrated that this insecticide 
is one of the best and safest materials to use on tomatoes for the control of 
the fruitworm, and is superior in the control of the pinworm. The active 
ingredient in cryolite is sodium f luoaluminate. Tests with the several brands 
and with different strengths of cryolite have not shown any great degree of 
difference in control when they were used at the same sodium f luoaluminate 
content and at the same rate per acre. For example, the same control can be 
expected fmm the use of a total of 180 pounds per acre of cryolite dust con- 
taining 35 percent of sodium f luoaluminate as can be expected from the use of 
a total nf 90 pounds per acre of a cryolite dust containing 70 percent of 
sodium f luoaluminate. As it is cheaper to mix and apply 90 pounds of a dust 
containing 70 percent of sodium f luoaluminate per acre than it is to apply 180 
pounds of the weaker dust, a 70-percent cryolite dust is . recommended for 
general use. 
Calcium arsenate. --Extensive experiments have demonstrated that calcium 
arsenate (undiluted - ) - is as effective as a cryolite dust containing 70 percent 
of sodium f luoaluminate when both materials «.re used at the same rate per 
acre. Calcium arsenate also has the added advantage of being cheaper than 
cryolite and in being more effective than cryolite in the control of hornworms 
and the best armyworm. Calcium arsenate has the disadvantage when compared 
with cryolite of not being so effective in the control of the pinworm, and in 
humid climates it may seriously burn the foliage and fruit. Calcium arsenate 
is preferred for use in localities where there is no chance of a pinworm 
infestation and in localities where it can be used without burning the plants 
and fruit. 
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