6 THE ALFALFA CATERPILLAR, 
TWO CLASSES OF RANCHES—PASTURE RANCHES AND HAY RANCHES. 
The alfalfa ranches in the Imperial Valley, Cal., can all be divided 
into two classes: (1) Pasture ranches, or those devoted entirely to 
the fattening or pasturing of cattle and hogs, and (2) hay ranches, 
or those on which the crop is utilized for hay. For convenience we 
can look at these separately. 
Pasture ranches.—It was noticed early in the summer, and the 
writer’s attention was called to the fact by a number of farmers, 
that ranches devoted to the raising of stock, either cattle or hogs, 
were rarely, if ever, seriously affected by the pest. On some dozen 
such ranches visited and inspected very few worms could be found, 
and the butterflies flying over the fields were never numerous. At first 
this was considered entirely due to the fact that there was hardly ever 
any bloom present for the adults to feed upon and that the greater 
part of the fields was kept grazed quite closely, making the condi- 
tion in pastured fields less favorable for the laying and development 
of the eggs. Under such conditions the number of eggs deposited 
is greatly reduced. Many of the eggs laid on the young growth 
under such conditions are destroyed by the grazing of the stock, and 
the percentage that develops is kept to a minimum. Later in the 
season it was noted that on the stock ranches visited the disease 
previously mentioned, which is common to lepidopterous larvee, was 
more prevalent than on hay ranches. All the factors determining 
this difference have not been ascertained, but the fact itself is quite 
significant. 
On some of the ranches coming under the writer’s observation the 
alfalfa was allowed to grow for some four weeks, or until it reached 
the height of about 20 to 24 inches. Cattle were then turned into the 
field, and within a few days the alfalfa became trampled. The 
ground and the alfalfa were very moist, there being more or less 
dew present every morning, and droppings from the cattle and hogs 
naturally brought about a foul condition in the field, assisting in the 
retention of moisture. Whether as a result of these conditions or as 
a coincidence, the contagious disease appeared to the writer to be 
much more prevalent in these fields than elsewhere. 
Hay ranches—It is on ranches and fields from which successive 
crops of hay are taken that the height of the damage is reached. In 
such fields the conditions for the development of the species are as 
nearly ideal as possible, and here the worms are ordinarily unmo- 
lested in their feeding and growth. The period elapsing from the 
time that one crop is cut until another is ready to harvest so nearly 
coincides with the length of the period necessary for the develop- 
ment of any one generation of the butterfly that the cutting of the 
hay, as ordinarily carried on, does not reduce their numbers or dis- 
turb their work, since the worm will likely be in the advanced stage | 
[Cir. 133] 
