Key to the Rhopalidae of Illinois

1 Lateral pronotal margins distinctly notched behind anterior margin ( Serinethinae); conspicuously colored, black and red; length 11 mm or more................................................................................ 2

- Lateral pronotal margins straight or slightly sinuate, without distinct notch behind anterior margin ( Rhopalinae); generally inconspicuously colored; length usually a little more than 9 mm ............................................... 3

2 (1) Bucculae short, not extending beyond middle of head ( Boisea); red dorsal markings present on pronotum and hemelytra............................................................................................ Boisea trivittata

- Bucculae long, reaching base of head ( Jadera); red dorsal markings limited to lateral margins of pronotum, hemelytra com- pletely black........................................................................ Jadera haematoloma

3 (1') Metafemur incrassate, bearing a series of prominent spines ( Harmostini)........................................ 4

- Metafemur not incrassate, lacking prominent spines......................................................... 6

4 (3) Connexiva widened, distinctly exposed laterally beyond margins of hemelytra................... Aufeius impressicollis

- Connexiva not widened, completely covered by hemelytra in dorsal view........................................ 5

5 (4') Scape short, slender, barely reaching apex of tylus; costal margin of hemelytra with fuscous spots... Harmostes fraterculus

- Scape long, thickened, surpassing apex of tylus; costal margin of hemelytra unicolorous, pale........ Harmostes reflexulus

6 (3') Metatibia distinctly annulated with black; rostrum reaching, or often surpassing, third sternite....... Niesthrea louisianica

- Metatibia without black rings, although often speckled with fuscous spots; rostrum not surpassing third sternite......... 7

7 (6') Apical margin of male genital capsule somewhat emarginated; female with ultimate tergite broadly triangular; coloration lighter, pale dull yellow to reddish......................................................... Arhyssus lateralis

- Apical margin of male genital capsule more or less straight; female with ultimate tergite acutely triangular; coloration darker, dark gray-white to red-brown or fuscous-black............................................ Arhyssus nigristernum