6 
bulletin 98. 
Analyses by the chemists at the sugar factory indicate a- loss of 
about 2 per cent, in both sugar content and in purity in beets 
that were defoliated badly during August. Probably more than 
1000 acres of beets suffered substantial loss from the web-worm in 
Colorado last year. 
life and habits of the insect. 
The worms that were in the beet fields last August disap¬ 
peared by burrowing into the ground to the depth of an inch or 
two and spinning about themselves white silken tubes from three- 
fourths of an inch to one and one-half inches in length, and three- 
sixteenths of an inch in diameter. A few of these worms changed 
to pupae and emerged again as moths during September, but near¬ 
ly all of them have spent the winter as worms in the silken tubes. 
Mr. G. P. Weldon, a special student in entomology, dug 69 of 
these tubes from one square foot of ground in a badly infested beet 
field on Aug. 31. On the same day he opened m tubes and 
found 13 pupae and 97 worms. He also noted that the moths were 
quite numerous in the field, more so than a number of days pre¬ 
vious. Moths which the writer placed over beets in cages Aug. 
25 deposited eggs which began hatching Aug. 3;. O11 September 
20, I visited beet fields in the vicinity of Wellington (r2 miles 
northeast of Fort Collins) in company with Mr. FTed W right, 
Agriculturist of the F A ort Collins Sugar Factory. The worms had 
disappeared but, although the day was cold, several of the moths 
were taken and many of the secondary parasites ( M. agilis) over 
the beets, but there was no September brood of worms seen or 
heard from. Mr. Johnson took a few moths as late as Oct. 12. 
Judging from the investigations by Riley and Howard, and 
Pu'uner in Nebraska and our own records at FT Collins, it is prob¬ 
able that the spring brood of moths will begin hatching about the 
iotli of May in the beet growing districts of the northern portion 
of the State, and probably about the first day of May in the Ar¬ 
kansas valley. We have found the moths very numerous at 
Fort Collins front the iotli to the 25th of May, and it is probable that 
they are depositing the first brood of eggs at about this time and 
somewhat earlier in the warmer sections as at Rocky Ford and 
Sugar City. At this time the beets are not up or are too small to 
attract the moths so that probably pigweed ( Chenopodium) alfalfa 
and other plants that are more advanced serve as food for the early 
brood. About Sterling, Mr. Johnson noticed that the beets planted 
after the 25th of June escaped injury from the worms. 
The second brood of moths, judging from our records, are 
most numerous at FT Collins, about the last week in June which 
should give a brood of worms about the 10th of July and this is 
the brood that did some injury to beets, onions and cabbages near 
