34 



BULLETIN 100, U. S. DEPARTMENT OF AGRICULTURE. 



MS 



Y&X 



m 



;-€ 



Fig. 18.— o, Monellia caryw, antenna of male; 

 b, Monellia caryella, two views of right an- 

 tenna of male. (Original.) 



occurs a large black spot on the pleurae. 

 Abdomen unarmed, pale green or green- 

 ish yellow; segments 1 to 8, inclusive, 

 with two dusky brown oval spots on 

 each. Cornicles pale, concolorous with 

 the body, very small, considerably 

 broader than long. Cauda concolorous 

 with the abdomen, globular. Abdomen 

 about as long as head and thorax com- 

 bined, not wider than the thorax. 

 Beak pale, barely reaching second 

 coxae. Sternum and underside of the 

 eighth abdominal segment black. 



Measurements: Length of body, 1.57 

 mm.; width of body, 0.62 mm.; ex- 

 panse of wings, 4.62 mm.; antenna, 

 joint I, 0.080 mm.; joint II, 0.041 mm.; 

 joint III, 0.412 mm.; joint IV, 0.317 

 mm.; joint V, 0.260 mm.; joint VI, 

 0.175 mm.; filament, 0.108 mm.; cauda, 

 0.067 mm.; cornicles, 0.009 mm. 



Described from three speci- 

 mens, Walnut Creek, Cal., 1912 

 and 1913. 



MONELLIA CALIFORNICA Essig. 



Monellia califomicus Essig, Pomona 

 Jour. Ent.,v.4, no. 3, p. 767, Nov., 

 1912. 



In southern California feeding 

 on the underside of the leaves of 

 the California black walnut 

 (Juglans californica) there has 

 recently been found a plant- 

 louse closely allied to Monellia 

 caryse and M. caryella. The 

 writer has never seen this aphis 

 in nature, but has received speci- 

 mens from Mr. Essig, who de- 

 scribed it. 



KEY TO THE SPECIES OF MONEL- 

 LIA KNOWN TO OCCUR IN CALI- 

 FORNIA. 



The following key will serve 

 to distinguish the four species 

 of walnut aphides occurring in 

 California. 



