February, ’24] 
JONES: CORN BORER PARASITES 
117 
blackbirds and grackles have been observed on various occasions, feeding 
upon the larvae in the spring. 
Similar bird activity has also been observed in the eastern and western 
areas of infestation in New York State. 
Status of the Infestation in all Areas 
A brief statement concerning the status of the infestation in all areas 
where the insect is known to be present, may be of interest. 
In New England the past season witnessed a very marked reduction 
in the intensity of infestation and injury. During a field survey of 222 
fields in 22 representative towns, the stalk infestation was found to have 
decreased 46.4% (56.2%-30.1%) as compared to 1922, while the larval 
population decreased 71.3% (399.0-114.5 per 100 stalks). The principal 
factors contributing to this decrease were (1)—Due to the cool dry 
* conditions, only 60% of a second generation developed; (2)—11.3% of 
the second generation (fertile) eggs dried up; (3)—61.4% of the second 
generation eggs were parasitized; (4)—The mean nocturnal tempera¬ 
tures during the oviposition period were below the optimum temperature 
requirements for normal oviposition. (by approx. 10 degrees). 
In New York State the degree of infestation remained about the same, 
and occasioned very little commercial loss. 
In Ohio and Michigan there was a marked increase in the intensity of 
infestation, as well as a considerable increase in size of the area infested. 
In a field survey, which included 133 fields of the lake counties, an 
average of 1.83% of the plants were infested with an average of 1.4 
larvae per infested stalk (2.58 larvae per 100 stalks). While but very 
little commercial injury resulted in Ohio or Michigan during the past 
season, the rapid increase in intensity of infestation in this area since 
1922 must be considered as very important. 
PARASITE INTRODUCTIONS: EUROPEAN CORN BORER 
(PYRAUSTA NUBILALIS HUBN.) 
By D. W. Jones, European Corn Borer Laboratory, U. S. Bureau of Entomology, 
Arlington, Mass. 
Abstract 
Native parasitism is practically negligible except in the case of the sporadic egg 
parasite, Tnchogramma minutum Riley. 
European parasites are studied at Hyeres, France, and shipped to Arlington,Mass., 
for liberation and breeding. 
