V HYTOPHAGA CERAMBYCIDAE 287 



There are numerous Longicorns that bear a great resemblance 

 in form and colour to Insects to which they are not related. 

 Haensch ^ has noticed that species of the genus Odontoccra 

 resemble various Hymenoptera, one species being called 0. 

 liraconoides ; he also observed that these Hymenoptera - like 

 Longicorns, instead of withdrawing their underwings under the 

 elytra as beetles generally do, vibrate them rapidly like Hymen- 

 optera. A large number of Longicorns stridulate loudly by rubbing 

 a ridge inside the pronotum on a highly specialised, striate surface 

 at the base of the scutellum, and therefore covered up wheu the 

 Insect is contracted in repose. A few produce noise by rubbing 

 the hind femora against the edges of the elytra, somewhat after 

 the fashion of grasshoppers. In this case there appears to be 

 comparatively little speciality of structure, the femora bearing, 

 however, more or less distinct small granules. The species of the 

 Hawaiian genus Plagithmysiis produce sound in both these 

 manners, the thoracic stridulating organ being beautifully de- 

 veloped, while in some species the margin of the elytra and 

 base of the femora are also well adapted for the purpose of sound- 

 production, and in a few species of the genus there are also 

 highly-developed stridulating surfaces on the hind and middle 

 coxae. This is the only case in which a beetle is known to 

 possess more than one set of sound-organs in the imago state. 

 Three divisions of this family are distinguished, viz. — 



1. Front coxae large and transverse ; protliorax with distinct side mar- 

 gins. Sub-fam. 1. Prionides. 



2. Pront coxae not greatly extended transversely, thorax not margined ; 

 last joint of maxillary palpus not pointed, usually broader (more or less) 

 than the preceding joint. Sub-fam. 2. Cerambycides. 



3. Pront coxae usually round and deeply embedded ; last joint of maxil- 

 lary palpus pointed ; front tibiae with a more or less distinct, slanting gi-oove 

 on the inner side. Sub-fam. 3. Lamiides. 



The Prionides are on the average considerably larger in size 

 than the members of the other divisions, and they include some of 

 the largest of Insects. The Amazonian Titanus giganteus and the 

 Pijian Macrotoma heros are amongst the most gigantic. Some 

 of the Prionides have a great development of the mandibles in 

 the male sex analogous to that we have already noticed in 

 Lucanidae. The larvae of the large Prionides appear in various 

 parts of the world to have been a favourite food with native 



1 Berli'/i. ent. Zeitsehr. xli. 1896, SB. p. 22. 



