38 ILLINOIS BIOLOGICAL MONOGRAPHS (356 



of segments; annulation sometimes obsolete. A few subfamilies of 

 Tenthredinidae. 



Nest-builders. — Thorax with seta-like segmented legs; abdomen without 

 larvapods; antennae long, setaceous, seven-segmented; mouth-parts nor- 

 mal; ultimate segment with distinct subanal appendages and a minute 

 hook-like caudal process on caudo-meson of tergum; ocellarae present; 

 web-spining leaf-rollers, Pamphiliidae. 



Borers. — Thorax with rudimentary legs, tarsal claws never present; 

 abdomen without larvapods, ultimate segment with a distinct suranal 

 process or with a pair of subanal appendages; mouth-parts somewhat 

 modified, maxillary and labial palpi reduced in number of segments; 

 ocellarae wanting or with vestigial eye-spots; metaspiracles sometimes 

 functional, as large as abdominal ones; wood-borers and stem-borers, 

 Siricidae, Xiphydriidae, and Cephidae. 



Parasites. — Body grub-like, thoracic and abdominal legs wanting; 

 mouth-parts modified, maxillary and labial palpi obsolete; ocellarae 

 wanting; antennae one-segmented; parasitic larvae, Oryssidae. 



The larvae of the typical Tenthredinoidea are readily differentiated 

 from the larvae of other Entometabola by the presence of a single ocellara 

 on each side of the head and, usually, six or more pairs of larvapods, none 

 of which are provided with crotchets, and never occur on first and ninth 

 abdominal segments. The characteristic mouth-parts include four- 

 segmented maxillary palpi and three-segmented labial palpi. The character 

 of the antennae, the number of ocellarae and larvapods, the charac- 

 ter of the mouth-parts, especially maxillary and labial palpi, and the 

 presence of thoracic legs distinguish the leaf-miners and wood-borers of 

 the Tenthredinoidea from other leaf-miners and wood-borers, such as 

 certain Lepidoptera, Coleoptera, and Diptera. The larvae of Hymenop- 

 tera other than Tenthredinoidea are distinguishable from those of the 

 latter as follows: They are apodous, thoracic and abdominal legs being 

 always wanting; the mouth-parts are vestigial, maxillary and labial 

 palpi, if present, papilliform, never distinctly segmented; ocellarae are 

 never present; and suranal process and subanal appendages are always 

 wanting. The larvae of the Oryssidae are separable from other hymen- 

 opterous larvae on the basis of the characters used in the definition of that 

 family elsewhere. 



FAMILIES OF TENTHREDINOIDEA 



1(6) Thoracic legs present, either normal in form, distinctly segmented, or modified, if 

 modified, fleshy or conical, if conical, head and body distinctly depressed; larvapods 

 either present or wanting 2. 



2(5) Thoracic legs normal in form, not seta-like, rarely mamma-like; larvapods usually 

 present; subanal appendages wanting; antennae usually with less than seven seg- 

 ments 3. 



