27 
The identity of this fungus species was in all these cases de¬ 
termined by artificial cultures made from the specimens collected. 
The spontaneous appearance of Sporotrichum in the field was 
much more frequently reported in 1894 than in the preceding 
year, the drouth being in fact less severe and continuous, and the 
chinch-bug much more abundant. A general prevalence of mus- 
cardine to some small extent on chinch-bugs in the fields of south¬ 
ern Illinois was detected in June, and again in September and 
October, all trace of it having in the meantime disappeared with 
the advent of a long midsummer period of heat and drouth. 
Particulars to this effect may be found farther on in this paper 
in the description of experiments Nos. 53, 55, 57, 60, 63, 64, 65, 
66, and 67 of the series for 1894. 
Number and Nature of Experiments. 
The list of recorded experiments in field and laboratory for the 
four years mentioned numbers two hundred and eighty-five, of 
which one hundred and one belong to the year 1891, eighty-six to 
1892, eighteen to 1893, and eighty to 1894. The work of the first 
of these four years was naturally largely devoted to culture ex¬ 
periments and to laboratory experiments with infection methods— 
thirty-nine of the former and forty-one of the latter for that year. 
The work of 1892 consisted chiefly of variations and elaborations 
of that of the preceding year, and included one field experiment. 
Other parasitic fungi (Botrytis tenella and Isaria leprosa) were also 
taken up and similarly handled. In 1893 especial attention was 
first given to experiments for the introduction of the chinch-bug 
diseases in the field, and in 1894 a general programme of labora¬ 
tory experiments and field distributions was entered upon, some 
two thousand of the latter being made during the year. The most 
important work of this season consisted in field experiments on a 
large scale, made by assistants of the office and by others person¬ 
ally known to me, which experiments were followed systematically 
throughout the season and studied in detail from month to month. 
Summary of Economic Results. 
The principal economic outcome of this whole investigation may 
be thus briefly summarized: 
1. White muscardine of the chinch bug is a contagious disease 
due to parasitism by the fungus species Sporotrichum globuliferum. 
It affects a large number of other insects as well, and probably 
never dies out entirely over any large area of the State, but is always 
sufficiently prevalent and common under all conditions to furnish 
a suitable beginning for a spontaneous spread wherever an insect 
species, like the chinch-bug, becomes for a time superabundant 
under conditions favorable to the growth and reproduction of the 
fungus characteristic of this disease. 
2. The conditions necessary to its appearance among chinch- 
bugs on the epidemic scale are an abundance of the bugs them¬ 
selves and a considerable amount of wet weather with not too 
low an average temperature. 
