AMERICAN IIYMENOPTERA. 331 



Antennge multiarticulate, the two basal joints straight, the remain- 

 der insei'ted obliquely; in the males pectinate, in the females serrate. 

 Australia. 



58. TARPA, Fabr. 

 Tarpa, Fabr. Syst. Piez. 1804, 19. 

 Megahdontes, Latr. Hist. Nat. des Ins. 3, 302. 

 Cephahia, Jurine. 

 Diprion, Schrank. 



Wings with two marginal, and four submarginal cells; lauceolate cell 

 with oblique cross-line. 



Antennae 15 — 18-jointed; generally the middle articles are prolonged 

 obliquely and serried one against another. 

 Posterior tibiae with two side spurs. 

 Europe, Asia. 



59. LYDA, Fabr. 

 Lyda, Fabr. Syst. Piez. 1804, 43. 

 Pamph/lius, Latr. Hist. Nat. des Ins. 3. 

 Cephaleia spec. Jurine, Hym. 1807, 65. 

 Psen, Schrank. 

 Tenthredo spec. Panz. Lin. &c 



Wings with two marginal, four submarginal and three discoidal cells; 

 lanceolate cell with oblique cross-line, under wings with two inner cells. 



Antennae setaceous, slender, 19 — 86-jointed, the 1st and 3rd gener- 

 ally the longest. 



Head generally as wide as thorax ; body stout ; abdomen much flat- 

 tened ; nasus rounded or slightly emarginate; labrum obtusely lance- 

 shaped ; mandibles lengthened, 3-toothed ; maxillary palpi 6-jointed, 

 the two basal joints short; labial palpi 4-jointed, the longest, thick- 

 ened in the middle. 



Anterior tibiae with two or three spurs; posterior tibiae with five 

 spurs. 



Larvae with six pectoral and no abdominal legs; two 3-jointed anten- 

 nae-like organs at the side of the head ; a horny appendage behind the 

 after segments. These larvae live in companies in webs upon pines and 

 some fruit trees. Westwood enumerates several species which live up- 

 on leaves of the pear, the aspen and the rose. Hartig has figured a 

 species upon the pine. Each larva spins for itself a separate case with- 

 in the larger webs. It forms a cell in the ground, lined with silk, 

 in which to pass the pupa state. They do not often appear in such 

 numbers as to be very injurious to vegetation. 



