24 BULLETIN 918, U. S. DEPARTMENT OF AGRICULTURE. 
in the same boll. During the latter part of the season, when the 
infestation is heavy, an average of 6 or 7 larvae is found per boll and 
individual bolls may contain many more. One boll was examined 
that contained 26 larvae. The number for all bolls examined through- 
out the season of 1919 averaged 2.5. 
PROLIFERATION OF BOLLS. 
The presence of larvae often causes the bolls to form abnormal 
growth or proliferation. Proliferation is described by Dr. W. E. 
Hinds CO as: 
The development of numerous elementary cells from parts of the bud or boll which 
are themselves normally the ultimate product of combinations of much more highly 
specialized cells. The resulting product is thus composed of comparatively large, 
thin- walled cells, which are placed so loosely together that the resulting formation is 
of a soft texture, and has a granular appearance which may be plainly seen with the 
unaided eye. 
Greenish white or discolored brownish opaque swellings are formed 
on the inner wall of the carpel, the seeds themselves proliferate, 
and very little if any lint is formed on them. This spongy mass of 
granular cells develops much more rapidly than lint, thus occupying 
the space that would have been rilled with lint. Badly proliferated 
bolls contain but little lint, and this is matted or felted and of poor 
quality, thus greatly increasing the damage done by the pink boll- 
worms. Proliferous seeds are not confined to those actually attacked 
by the larvae. The irritation caused by the presence of the larvae in 
a boll or the stimulation from proliferation in seed actually injured 
causes other healthy seed to proliferate. The percentage of proliferous 
bolls increases very rapidly with the advance of the season, which is 
simultaneous with the increase of the number of bolls attacked by 
the pink bollworm and with the number of larvae in each boll. The 
Egyptian cotton grown at the laboratory was much more severely 
affected by proliferation than were the short-staple varieties. Larvae 
occasionally are killed by proliferation, but from general observa- 
tions it is thought that not more than one-tenth of 1 per cent are 
killed in this way. The result is by far more detrimental than 
beneficial. 
DAMAGE CAUSED BY THE PINK BOLLWORM. 
The damage by the pink bollworm is caused by the feeding of 
the larvae on the squares and blooms, the walls and partitions of 
the bolls, and the lint and seed of the cotton. Upon entering the 
boll after hatching the larvae feed on the lint and tender tissues of 
the boll during its earlier stages of growth; in the latter stages the 
larvae feed almost exclusively on the seed, thereby arresting the 
development of the lint and seed and also destroying the seed itself. 
In passing from seed to seed and from lock to lock the larvae cut and 
