8 
machinery portion of the cotton-worm investigation, was sent to Ala- 
bama to make field tests of the largest and apparently most practical 
machines which had been devised. He found that the large machines, 
so arranged as to underspray sixteen rows of cotton at once, were com- 
paratively impractical, except in a very few cases. Were cotton so 
planted that the rows were equally spaced the machine would work very 
well, but the inflexibility of the larger machines prevented them from 
conforming to inequalities of the ground and to uneven rows. Every 
cotton planter knows that in an average cotton field the necessities of 
the case will not allow of ideally true rows. The rows must run wider 
or narrower according to the quality of the soil and the size of the plant 
a certain soil will produce. It was found, therefore, that an attempt 
to underspray more than four rows at once was practically useless. 
Such extensive remedial work against this insect as was planned in 
the Fourth Report of the United States Entomological Commission 
_ has not of late been 
found necessary in 
the South. Per- 
haps the main rea- 
sonis that a change 
has taken place in 
Southern agricul- 
ture, which has 
frequently been 
urged by writers 
upon economic en- 
tomology as most 
conducive to the 
limitation of wide- . 

Fia. 5.—Pimpla conquisitor, one of the principal parasites of the cotton 
caterpillar: a, larva, enlarged; b, head of same, still more enlarged; spread damage by 
¢c, pupa; d, adult female, enlarged; e, f, end of abdomen of adult male, 4 ny given species 
still more enlarged (from Fourth Rept. U. S. Entom. Comm.). 
of injurious insect. 
This is the greater diversification of crops. Cotton is no longer planted 
everywhere, as in the broad fields which were so common twenty years 
and more ago. As a characteristic instance, we may take the case of 
a prominent planter at Columbus, Tex., who in 1880 had 500 acres of 
cotton under cultivation in a bend of the Colorado River. In 1894 he 
had of the same area 300 acres in corn, 100 acres in Johnson grass, and 
only 100 acres in cotton. It is readily seen that such.a breaking up of 
the immense cotton fields of the South will to a great extent prevent 
any undue multiplication of the caterpillars and consequent migration 
northward of the moths. Twenty years ago, moreover, remedial work 
on a large scale was not attempted by cotton planters. Later the 
knowledge of the importance of poisoning for the early broods has 
inspired planters with a feeling of confidence, which has since steadily 
grown, both as the result of successful remedial work on a more or less 
small scale and the undoubtedly smaller numbers of the worms. 
