148 
about an inch long when full grown. The general color varies from 
purplish brown to whitish brown, according to age, and it is marked 
with five white stripes, one running down the middle of the back, 
and two on each side * * *. The stripes nearly vanish as the 
larva matures [Fig. 40, c]. The head and top of the neck, and the 
leathery anal shield at the opposite end of the body are light reddish 
yellow with a black stripe on each side." 
The young caterpillar first feeds within the stems of grasses or 
w^eeds, but as it becomes larger it is compelled to seek thicker- 
stemmed plants, and it is at this time that it begins to infest garden 
vegetables. In northern Illinois, in 1908, half-grown larvae were 
found in tomato stalks the middle of June, when fully half the plants 
in the field had been killed by. them. The larva usually enters the 
stem near the base and burrows upwards. When full grown it 
changes into a reddish brown pupa (Fig. 40, c) within the stalk, 
usually below the original entrance-hole, and later the grayish moth 
(Fig. 40, a) emerges. According to Prof. F. L. Washburn * the 
eggs of this moth are deposited in masses on the stem of the plant 
near its base. It is supposed that they are laid in grass lands in fall, 
and that they hatch the same season or the following spring. 
Economic Procedure. — After plants have become infested, no 
remedy can be used to save those individual plants, and they should 
be pulled up and burned immediately to prevent the larvae from en- 
tering other plants, and also to decrease the number of the borers 
for the next year. 
In spring, vegetation around tomato, potato, and corn fields 
should be watched, and if it is wilting or dying it should be exam- 
ined to learn if this borer is present, in which case the weeds should 
be cut and destroyed without delay. 
Late fall-plowing of infested fields is advised in order to bury 
the eggs, which, as already said, are supposed to be laid in grass or 
weedy land in fall, and all weeds, not only in the fields but along 
the roadsides adjoining them, should be destroyed at this time. 
Preparation of Insecticides for Use against Insects 
Injurious to Garden and Hothouse Vegetables 
From the economic point of view insects are divisible into two 
classes; those which chew and swallow the tissues of the plant, and 
those which suck their juices. Insects of the first class — cabbage- 
worms, potato-beetles, and cutworms, for example — can usually be 
destroyed by one of the so-called stomach poisons listed on page 
149; but those of the second class — plant-lice, thrips, the white-fly, 
*Preliminary Report upon Work with the Stalk Borers in Minnesota. 12th Rep. 
State Ent. ISIinn., p. 151. Dec, 1908. 
A 
