U. S. D. A., B. E. Bui. 95, Part VII. Issued October 16, 1912. 



PAPERS ON CEREAL AND FORAGE INSECTS. 



THE ALFALFA LOOPER IN THE PACIFIC NORTHWEST. 



{Autographa gamma calif ornica Speyer.) 



By J. A. Hyslop, 

 Agent and Expert. 



INTRODUCTION. 



The first record of this moth of economic importance is an un- 

 published note by Mr. Theodore Pergande 1 made June 29, 1895, 

 wherein he records having received from Mr. E. W. Baker, of Grand 

 Junction, Colo., a few specimens of the larvae of a Plusia, determined 

 on the note as "Plusia gamma ( ? ) ," with the statement that the larvae 

 do much damage to the leaves and blossoms of alfalfa. Material was 

 not preserved, so actual specific determination is impossible. As 

 Plusia gamma L. is a European species, presumably it was P. gamma 

 calif ornica Speyer, now known as Autographa gamma calif ornica. 



The depredations of this species have not as yet been sufficiently 

 serious to cause damage in the Palouse region of Washington and 

 Idaho, although its attacks on alfalfa and clover have attracted the 

 attention of many ranchers. The larvae are usually very numerous in 

 the early spring and gradually increase in numbers until the first 

 hay cutting, when they appear to reach the maximum. They do not 

 seem to be inconvenienced by the removal of the hay crop, but imme- 

 diately turn their attention to the young second growth, on which 

 larvae are to be found throughout the summer until the early frosts. 



The alfalfa looper in this locality has been held in check by a 

 number of parasites and a disease, but any change in environmental 

 conditions which might tend to reduce the efficiency of these natural 

 checks or accelerate the reproduction of these moths would undoubt- 

 edly cause a serious outbreak, such as occurs periodically with the 

 highly parasitized white-marked tussock moth, Hemerocampa le'u- 

 costigma S. & A. It does, however, offer an excellent illustration 

 of the statement, so often made, that many injurious insects are held 

 in check by their parasites. Such cases as the above justify the arti- 



1 Bureau of Entomology Notes, No. 6692. 



109 



