44 BULLETIN NO. t, DIVISION OF ENTOMOLOGY. 
an emulsion of one per cent. kerosene, thoroughly applied, was fatal to — 
all larvee it reached, and harmless to the cotton-plant. 
I noted that as soon as sprinkled the small larve stopped eating, 
straightened, and quickly fell to the ground. Older larve would trem- 
ble, evacuate feces, and hang suspended some time. The anal extrem- 
ity lived longest. 
The addition of one pound sulphide of potassium to forty gallons of 
any emulsion seemed to increase the rapidity of its toxie action, but it 
is objectionable as to smell and its destructive action upon rubber hose. 
The sulphides will bear further study. 
Still, with all these emulsions, their cheapness and safety, I have a 
grave doubt as to the applicability of any to long-staple cotton. 
I tried a number of experiments to determine the minimum quantity 
needed to thoroughly spray an acre of cotton during August or Sep- 
tember. In one very carefully conducted experiment I found most of 
the plants averaged 6 feet high, in rows of 4 feet apart, and 2 feet be- 
tween the plants in the drill. 
In this case 160 gallons barely sufficed for one-half an acre, and as it 
could not be applied from a eart it was hand-carried. Two field hands 
required four hours to complete the experiment. 
The labor of preparing solutions, and of carrying and using a fount- 
ain pump, will prevent small farmers, especially colored people, from 
trying these remedies. 
‘The cost of this experiment was, 160 gallons solution C’, 70 cents ; 
labor, 60 cents, or $2.60 per acre, and with the close margin between 
profit and expense in cotton-growing, this slight cost will deter many. 
Invasions of cotton-worms in October do but little harm. The larvee 
feed only between the temperatures of 72° and 92° F. The night tem- 
perature of October averages 65° to 68°, and the larve remain quiet 
till the mercury stands at 72°. At 50° the larve rapidly turn yellow ; 
at 45° they swing helpless from the leaves and soon die. 
The pup survive 35° if shaded from the sun and the cold does not 
last more than a few hours. 
Early in the season the Heliothis destroyed at least one-third the 
cotton-bolls, and now cotton-planters complain of the cotton-stainer. 
These insects have done more damage here than all the Aletia. In 
many cases the young bolls are found filled with the weevil (Sylvanus 
quadricollis Guér.) and small red worms (Batrachedra rileyi Walsing- 
ham), and planters believe that tiny worms act independently of the 
Heliothis. These larvie are described on page 98, Patent Office Report, 
Agriculture, 1855. 
The larvee of the Agrotis (generally annexa) do some damage to early 
cotton—February-planted—and two or three species of grasshoppers 
and crickets at one time threatened the destruction of the entire crop. 
Plant-lice were not so numerous, for some reason, on cotton, though 
whole crops of melons were destroyed by one species of Aphis. 
Se 
phn Mata. 
————— ee 
