PROGRESS REGARDIXG SUGAR-BEET WEBWOKM. 
61 
This, however, is not the case, but their apparently sudden appear- 
ance is explained by the fact that the young webworms are easily 
overlooked and that during the last few days before they reach 
maturity their growth is very rapid. It frequently happens that 
from 50 to 300 eggs are deposited on single beet plants, and in ex- 
treme cases as many as 500 eggs may be so placed. The worms hatch- 
ing from these eggs remain upon the beet on which they hatched 
until they reach maturity, unless all the leaves are destroyed and they 
are thus forced to crawl 
to another beet to obtain 
food. 
CHARACTER OF INJURY. 
It is impossible to state 
definitely the damage to 
sugar beets that an infes- 
tation of webworms may 
cause, as this may vary 
from almost no percepti- 
ble loss to the complete 
destruction of the infested 
plants, the extent of the 
injury depending on the 
number of webworms 
present, the size of the 
infested beets, and various 
other factors, such as cli- 
matic conditions, soil fer- 
tility, and water supply. 
As previously mentioned, 
small beets may be killed 
outright (see fig. 14), 
while larger beets may 
be completely stripped 
of foliage. With large 
beets new leaves will usually be put out promptly and their 
apparent recovery will take place quickly, especially if they are 
irrigated as soon as possible after the defoliation. Although new 
leaves are soon put out. defoliation retards the growth of the beet 
roots. (See fig. 13.) The writer has seen beet roots which at the 
time the tops were defoliated, in early July, were more than an inch 
in greatest diameter that made absolutely no gain in weight or 
size for three weeks after the leaves were destroyed. It might be 
added that these beets were in good, fertile soil and were watered 
51094°— BnU . 109. pt 6—12 2 
Fig. 12.- 
-Sugar beets defoliated by the sugar-beet 
webworm in July. (Original.) 
