298 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



620. Cuterebra fontinella Clark 



The same as emasculator Fitch. Buck Mt., VII-10; Cor- 

 vallis. 



621. Cuterebra leporivora Coq. 



Corvallis, VIII-28. Reared from Mus musculus (Brid- 

 well). 



622. Cuterebra tenebrosa Coq. 



La Grande, VII-6; Corvallis, IV. 



Family TACHINID^E 



Fig. 32. Dioncea nitoris Coq. 



The family is a large one, 957 species being listed in 

 Aldrich's Catalogue. They are usually short, stout, unus- 

 ually bristly flies. The antennal arista is always bare and 

 the squamae, large. Flowers attract many of the species and 

 they are often seen flying about rank vegetation. Some of 

 the smaller species resemble the common house-fly in general 

 appearance. 



Many of the species are very beneficial, the larvae being 

 parasitic on injurious insects. A few attack beneficial in- 

 sects, but only a small percentage. They are the chief con- 

 trol of many caterpillars. From one to one hundred grubs 

 may work on one host larva, much depending on the size of 

 the victim. 



Most of the species listed below were determined by Dr. 

 J. M. Aldrich, or the determinations already made were 

 verified by him. 



623. Gymnoclytia immaculata Macq. 

 Dee and Hood River, VI-8 to VII-5 (Cole and Childs). 



624. Gymnoclytia occidua (Walk.) 

 Hood River, VI-3 (Cole). 



