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S. FOREST SERVICE 



/RESEARCH NOTE LS-53 



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I LAKE STATES _FOREST EXPERIMENT STATION • U.S. DEPARTMENT OF AGRICULTURE 



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-ield Key to the Adult nymenopterous Parasites 

 of the Spruce Budworm in Minnesota v^/ 



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The simple key presented here was devised for 

 field identification of the various adult hymenopt- 

 erous parasites of the spruce budworm ( Choriston- 

 eura fvmifermia ( Clem. ) ) in Minnesota. Using 

 easily recognizable morphological characters visi- 

 ble through a hand lens or low-power microscope, 

 it was designed to separate genera only. This level 

 is adequate for certain purposes. Where precise 

 species identification is necessary, parasites should 

 be sent to expert taxonomists. 



The species listed in table 1 are all of the 

 hymenopterous parasites recorded from thousands 

 of specimens reared from 1956 to 1961 in northern 

 Minnesota. Several of the genera contain only one 

 species in this list, so that identification to that par- 

 ticular genus also will indicate a particular species. 

 A few specimens could not be identified beyond 

 the genus because of insufficient or incomplete 

 material. At least two, and possibly three, new 

 species were recovered in the rearings. 



Key to Adult Hymenopterous Parasites 



1. Forewings with two veins or less; insects 3 



mm. or less in length ( Figs. 1-3 ) 2 



Forewings with numerous veins; insects long- 

 er than 3 mm. ( Figs. 4-9 ) 11 



2. ( 1 ) Head, thorax, and abdomen yellow; body 



length about 0.5 mm Trichogramma 



Head, thorax, and abdomen not yellow; body 

 length 1.0 mm. or greater 3 



3. ( 2 ) Head, thorax, and abdomen bright green 

 or blue; legs uniformly brown or yellow .... 4 

 Head, thorax, and abdomen black; body may 

 be irridescent; legs and antennae not neces- 

 sarily uniform in coloration 6 



4. ( 3 ) Body light yellowish green; legs uni- 

 formly yellow; antennae with yellow scape 

 and orange or brownish filament; abdomen 

 shorter than head and thorax combined; 



2.5 mm. long Psychophagus 



Body dark brownish green; legs and anten- 

 nae uniformly brown; about 3.0 mm. long . . 5 



5. ( 4 ) Abdomen robust, shorter than head and 

 thorax combined, and its length less than 

 twice its width; abdomen shining black ex- 

 cept basal half of first abdominal tergite 



metallic green Amblymerus 



Abdomen elongated, longer than or as long 

 as head and thorax combined, and its length 

 more than twice its width; abdomen uni- 

 formly bright or metallic green . .Habrocytus 



6. ( 3 ) Legs nearly uniform in coloration, either 



white, yellow, or tan 7 



Lego marked with contrasting colors, white 

 and black or white and brown 8 



7. ( 6 ) Face below antennae black; eyes gray 



or black Hyssopus 



Face below antennae white; eyes purple 



Euplectrus 



8. ( 6 ) Vertex of head rounded 9 



Vertex of head pointed Copidosoma 



MAINTAINED AT ST. PAUL 1, MINNESOTA, IN COOPERATION WITH THE UNIVERSITY OF MINNESOTA 



