59 
few years later disappear. They are destroyed by parasites or by 
climatic conditions and soon become rare species. This happened in 
the case of the pine insect, which was scarcely heard of before, and 
was one of the rarest insects in collections until it suddenly occurred 
in 1891 in such enormous numbers as to destroy millions of dollars 
worth of timber, but now it is practically extinct. Nota single living 
specimen has been found since the fall of 1892. Professor Johnson’s 
paper shows the great importance of the work he has undertaken, and 
his experience will be of inestimable value in dealing with Entire out- 
breaks of the pea louse. He thought the farmers of Maryland would 
make a great mistake by changing their locations for growing peas 
until perhaps a year has elapsed, because if the rule follows in regard 
to sudden invasions by indigenous insects they will soon disappear or 
become rare. 
Mr. Johnson said he was greatly obliged to Mr. Hopkins for his 
opinion, but there is so much money at stake that the growers could 
not let the matter rest awaiting nature’s relief. He believed fungous 
diseases, especially Lmpusa aphidis, is one of the factors which will 
bring about the temporary disappear ance of the pest. 
Mr. Galloway said the point in regard to the appearance < and dis- 
appearance of forms holds good in fungous attacks also, the most strik- 
- ing example being the potato blight. The same holds good in the 
passing of the Russian thistle. These things come and go and come 
again, and the principle holds good with fungous diseases as well as 
with insects. 
The next paper, by Mr. Galloway, was entitled: 
PROGRESS IN THE TREATMENT OF PLANT DISEASES IN THE 
UNITED STATES. 
By B. T. Gattoway, Washington, D. C. 
[Printed in the Yearbook of the Department of Agriculture for 1900. ] 
The next paper, by Mr. Webster, was entitled: 
METEOROLOGICAL INFLUENCES ON THE HESSIAN FLY. 
By F. M. Wessrer, Wooster, Ohio. : 
| Withdrawn for publication elsewhere. | 
The meeting then adjourned to Central Park to inspect Mr. South- 
wick’s spraying outfit. 
AFTERNOON SESSION, JUNE 23. 
Owing to the large number of papers to be read, it was resolved 
that each author be allowed ten minutes in which to present an abstract 
of his paper, and that all discussions be postponed until the papers had 
been presented. 
