171 
Mally, F. W.—Report on the Boll Worm of Cotton ( Heliothis 
armigerci Hubn). (U. S. Dept. Agr., Div. Ent., Bull. No. 
29, p. 59.) 
An account of experiments to determine the practicability of 
utilizing the germs of insect disease for the destruction of the 
boll-worm. Methods and special apparatus described, and details 
of observations and experiments given. Beside the boll-worm 
disease one of Plusici brassicce and one of Pieris rapce were 
under observation, and as the boll-worm was constantly exposed 
to infection from these cabbage insects difficult complications ex¬ 
isted, necessitating special experiments to determine the nature of 
the germ causing disease in the boll-worm. These are given in 
detail. The habits of the boll-worm, whether feeding upon corn 
or cotton, are such as to reduce to a minimum the chance of 
dissemination of the disease to which it is naturally subject, and 
also to some extent account for the failure of the diseases of 
Pieris rapoe and Plusia brassicce to destroy it. The climatic 
conditions in Louisiana are also thought to account in part for 
the moderate virulence of the Pieris germ, high temperatures be¬ 
ing kuo vn to have a devitalizing effect on many bacteria. The 
Plusia disease, on the other hand, is less virulent in cooler dis¬ 
tricts. Actual experiment only can justify the assertion that a 
disease artificially produced in one species may be communicated 
in the same manner to another. The experiments seem to indi¬ 
cate that the germs studied are facultative rather than true para¬ 
sites; that is to say, that certain conditions and environment are 
necessary to their development as parasitic organisms. The failure 
of such germs to produce economically important results when 
artificially introduced, should not weight against the availability 
of strictly parasitic organisms for economic ends. In conclusion, 
it is emphasized that “the biological and physiological properties 
of the germs, together with their environments, should first be 
studied and determined upon a purely scientific basis, without re¬ 
gard primarily to the attainment of practical results. 
Riley, C. Y. —Experiments with the European White Grub 
Fungus. (Rep. [U. S.] Sec. Agr. for 1892, p. 163.) 
Mention of experiments by foreign investigators which indicate 
that Botryiis lenella or Isaria densa is the best fungus for prac¬ 
tical use in disseminating disease among the larvae of the European 
white grub (Melolontlia vulgaris ), Dufour’s experiments indi¬ 
cating, however, that the “larger percentage of treated larvae re¬ 
sist the disease even in the laboratory, while in the field the pro¬ 
portion of affected larvae is considerably less.” Spores of this 
fungus received from Paris were used by Prof. Herbert Osborn 
at Ames, Iowa; by Prof. Lawrence Bruner at Lincoln, Nebraska; 
and by Mr. F. W. Mally at Washington, but the results were all 
unfavorable. 
