66 PASTURE AND RANGE. 
PEA FAMILY—Leguminosae. 
STEMLESS LOCO WEED—Ocytropis spp. DC., also known as 
Aragallus. 
Other Common Names: Loco Weed, Crazy Weed, Loco 
Vetch, White Loco. 
For many years stockmen of the west have been euftel- 
ing great losses from the disease known as “Loco.” Sey- 
eral agencies have at various:times been held 
responsible for the trouble. One opinion was 
that animals not regularly supplied with salt 
acquired the disease from eating the alkali so common 
in certain soils of the plains. This idea has been shown 
to be erroneous since cases of “Jocoing’’ have become 
known on ranges where the alkali could not .be obtained. 
Various plants were also blamed for the trouble and in- 
vestigation has proved that this is correct, there being 
now several distinct species of recognized Loco weed. 
The disease takes a peculiar course, not unlike’ the 
development of the drug habit in human beings. Horses 
and sheep are the animals usually affected, but cattle also 
become locoed in some cases. Animals may be pastured 
for years on ranges where the Loco Weed is found and 
show no ill effects, as they ordinarily avoid it: When one 
of them acquires the taste, however, it develops a crav- 
ing for the weed and hunts it incessantly. Sheep acquire 
the habit by imitation, and so it is important to remove 
all locoed animals at once from the flock. “ 
In chronic cases of locoism an immunity is developed, 
so that increasing quantities are necessary to produce 
. characteristic symptoms. In such cases there 
chronic is a continual craving for Loco Weed,. the 
animal nervously searching it out and feeding 
on it. Locoed sheep become more and more emaciated 
The Loco 
Disease 
a3 
