LEAFHOPPERS OF MAINE. 87 



Key to the Families of Jassoidea. 



A. Elytral nervures forking on the disk 



b. Ocelli located on the disk of the vertex Tettigoniellidae 



bb. Ocelli located on border of vertex or between vertex and front 



Jassidae 

 bbb. Ocelli located on front distinctly below border of vertex 



Bythoscopidae 



AA. Eb'tral nervures forking at base and running to apex of elytra, 



ocelli usually wanting Typhlocybidae 



Key to the Genera of Bythoscopidae. 



A. Antennae inserted in a deep cavity beneath a ledge, 

 b. Striation of pronotum transverse. 



c. Side margins of pronotum sharply keeled, of moderate 

 length. Macropsis^ 



cc. Side margins of pronotum not sharply keeled very short. 



Oncopsis. 

 bb. Striation of pronotum running obliquely from the middle of its 

 front margin to its hinder angles. Pediopsis. 



AA. Antennae inserted in a feeble cavity, their base free. 



b. Head with eyes wider than the elytra at the base, membrane 

 with an appendix. Idiocerus. 



bb. Head with eyes as wide as the elytra at base, no appendix. 



Agallia 



Oncopsis pruni Prov. 



Bythoscopus pruni Provancher Pet. Faune Canad. HI 290, 1890. 

 Bythoscopiis pruni Van Duzee Entom. Amer. VI, 227, 1890. 



A little smaller than fenestratus and generally darker, the elytra hya- 

 line with veins black, these being accentuated on the cross nerves so as 

 to form irregular cross bands and an apical band or spot. Length 4 to 

 4.5 mm. 



This appears to be one of the most common and widely distributed 

 species in the state. While described as from the plum and occasionally 

 taken on various plants including blueberry, poplar, etc., our collections 

 show it to occur very generally on birch and all other collections seem 

 to be in association with this tree so I believe this may be considered 

 the usual food plant for the larval form. At Orono it has been taker* 

 on many dates from June 5th to August 6th mostly on birch. At N> 

 Harpswell Aug. 12; Highmoor Farm Aug. 15th on birch and blue- 

 berry at Mt. Katahdin Aug. 20-21 st up to table land 4500 ft. elevation,, 

 at the latter place probably from willow as no birches were seen. Speci- 

 mens in the Boston Society of Natural History are from Calais. 



The species may be considered as covering in its distribution the birch 

 forests of the state and it must undoubtedly be counted an economic 



