58 PROC. ENT. SOC. WASH., VOL. 23, NO. 2, MAR., 1921 



All forms included in the key have: Four jointed antennae; 

 all legs of approximately same length; a stridulating organ is 

 never formed by special development of second and third pair 

 of legs; ocelli are not present; cutting edge of mandible never 

 tridentate. 



Key: 



1. Antenna shorter than headcapsule; antenna! appendix obtuse; ventral 



margin of labrum without transverse striation; cutting edge of mandible 

 without tooth; (North American)... ...Cyclocephala. 



Antenna as long as headcapsule; antennal appendix pointed conical; ventral 

 margin of labrum transversely striate; cutting edge of mandible poster- 

 iorly with a small tooth ... ...2. 



2. Stridulating structures absent on mandible and maxilla; (North Ameri- 



can) ...Macrodactylus. 



Stridulating structures present on mandible and maxilla ... ...3. 



3. Stridulating area of mandible with granules irregularly distributed, of 



maxilla with about twelve teeth; anal slit transverse, medianly angular; 



(North American) ...Phyllophaga (Lachnosterna). 



Stridulating area of mandible with granules in transverse fine lines, of 

 maxilla with about six teeth; anal slit transverse, crescent-shaped 4. 



4. Claws of third pair of legs abruptly shorter than of first and second pair of 



legs; respiratory plate with oblong holes in transverse rows; (North 

 American and European)... ...Anomala. 



Claws of third pair of legs same length as of first and second; respiratory 

 plate with angulate-rotundate holes, irregularly distributed 5. 



5. Epicranical suture inconspicuous and without elevated margins; (Euro- 



pean)... ...Phyllopertha. 



Epicranical suture with slightly elevated and medianly dark colored 

 margins .... ...6. 



6. Labrum coarsely granulate; mandibular mola with heel posteriorly concave 



and dorso-posterior angle shortly prolonged; with anterior lobe of crown 

 globular; anal segment ventrally with two posteriorly diverging rows of 

 about seven spines; (North American, introduced from Japan) Popillia. 

 Labrum posteriorly with closely set, rather large, oval, obtuse elevations; 

 mandibular mola with heel almost square and the dorso-posterior angle 

 slender, twice as long as wide; with anterior lobe of crown fusiform; 

 anal segment with two parallel rows of about ten spines; (North Ameri- 

 can) ...Undetermined grub; possibly Strigoderma. 



EXPLANATION OF FIGURES. 



Figures drawn by author. 



Plate V'. 

 POPILLIA JAPONICA Newman. 



Fig. 1. Abdominal spiracle: B, bulla with spiracular opening; R, respiratory 



plate with fine holes. 

 Fig. 2. Longitudinal section of spiracle: A, atrium; b, bulla; o, spiracular 



opening; r, respiratory plate; t, trabecula (one of those branched 



