POTATO DISEASES IN HAWAII. 31 
moth. The " poko " in the early summer months is a voracious 
feeder, and unless it is checked by artificial means it may entirely 
destroy the foliage of the potato vines. The " pokos " as well as 
the true cutworms are night feeders, which during the day may 
usually be found curled up in the soil at the base of the plant upon 
which the}' are feeding. 
Control. — The growers of potatoes in the islands have been quite 
successful in controlling these worms with a poison bait. Before 
the war it was customary to use a bait made of the highest grade 
of wheat flour and Paris green, a high grade of flour having been 
found economical by the farmers because it is finer and can be spread 
more thoroughly over the vines and over more plants than the 
coarser grades. The poisoned flour is dusted in the late afternoon 
over the plants and the soil at the base of the same. Some burn- 
ing of the foliage, or arsenical poisoning, results, but this is usually 
not serious (p. 35). This treatment is generally used and is con- 
sidered effective by the growers. The cost of the flour used is a 
not inconsiderable factor in the expense of growing the crop. As 
a substitute method for the control of these pests, the poison baits 
of which the formulas are given on page 1-t are now being success- 
fully used. It seems probable that the leaf-eating worms could be 
controlled by the use of arsenicals with Bordeaux mixture (p. 13). 
Paris green is used at the rate of 1 pound to 50 gallons of Bordeaux. 
Where Paris green is used the burning of the foliage is prevented 
by the life in the Bordeaux, or, if necessary, an additional quantity 
of lime, equivalent to the amount of Paris green used, may be added 
for the purpose of neutralizing the free arsenious acid. 
Mite Disease. 
Irish potatoes growing in Hawaii in dry, hot situations, whether 
irrigated or not. are frequently seen to dry up and die from the 
growing tip downward. The small young leaves turn brown or 
become bronzed on the under surface, get abnormally " fuzzy,'" and 
twist or curl up, and soon the shoots and leaves dry up and die 
(PI. XII). Often the plants grow well until about the time of 
flowering, when they gradually dry up and die prematurely. The 
yield of such plants is negligible. The young growth is found upon 
examination to be attacked by a multitude of minute mites, which are 
scarcely to be seen with a hand lens having a magnification of less 
than 20. These pests suck the juice from the tender foliage and 
ultimately kill it. 
This disease of the Irish potato seems to be a new one ; at least the 
writer has been unable to find such a malady mentioned in the litera- 
ture. A somewhat related disease is described under the name 
