INSECTA. 387 
Family XXIV. Tenthredineta s. Serrifera. Abdomen sessile, 
continuous with thorax, covering the origin of posterior feet, cylin- 
drical or ovato-oblong. Mandibles large, horny, acuminate, in- 
curved, mostly tridentate. Maxillary palps mostly sexarticulate, 
labials four-jointed or quadriarticulate. Labium cloven into three 
lacinie. Wings both anterior and posterior furnished with dis- 
tinct cells. Borer almost always occult, included in a bivalve 
sheath, compressed, cultrate, mostly serrate, composed usually of 
four sete (the upper one of other hymenoptera being here cloven to 
the base). Tibiz of anterior feet with two terminal spines. Larva 
(similar to caterpillars) with mostly twenty-two or twenty feet, 
feeding on leaves. 
Leaf-wasps. The larve mostly eat leaves like caterpillars, some 
live in gall-exerescences. These insects are often very destructive to 
trees, and the knowledge of them is therefore very important to the 
forester. Some also injure our potherbs. 
On this family, besides the Monograph of Hart1G noted above and the 
third part of the Forst-Insecten of RaTzEBURG, may be consulted: Kuve, 
Die Blattwespen der Fabrizischen Sammlung ; WIRDEMANN’S Zoologisches 
Magazin, 1. 3, 1819, s. 84—91, Tab. 11., and by the same, Uebersicht der 
Tenthredinete der (Berliner) Sammlung, in his Jahrbiicher der Insekten- 
kunde, 1. Bd. 1834, 8vo, 8. 223—253, Taf. 11. figs. 5—10; G. DAHLBOM, 
Clavis novi Hymenopterorum systematis adjecta synopsi larvarum scandina- 
vicar. eruciformium, Lund, 1835. 
A. Borer exsert. 
Xyela DALMANN, Mastigocera Kiuc. Antenne thirteen-jointed, 
with fourth joint longest (equalling or surpassing in length the 
nine terminal joints taken together). Borer of females of the 
length of abdomen. 
B. Borer occult. 
a) Antenne with numerous joints, (fifteen to thirty-six). 
Lyda Farr., Hartic, Pamphilius Larr. Antenne setaceous 
(nineteen- to thirty-six-joimted). Radial cells two, cubital four. 
Posterior tibie with three lateral spines. 
The larve of this genus live together socially in a web; they have, 
besides the six horny feet on the thoracic segments, only two propellers 
directed outwards at the hind part of the body. Comp. Harrie 1,1. 
Tab. vit. figs. 1—16, and RatzesurG, Forst-Insekten. 111. Tab. I. 
25—2 
