Scolytidae sometimes multiply to an enormous extent, attacking and destroying the trees in wooded regions. Much discussion has taken place as to whether or not they are really injurious. It is contended by one set of partisans that they attack only timber that is in an unhealthy, dying, or dead condition. It may be admitted that this is usually the case; yet when they occur in enormous numbers they may attack timber that is in a sort of neutral state of health, and so diminish its vigour, and finally cause its destruction. Hence it is of great importance that they should be watched by competent foresters. The larvae of Scolytidae are said to completely resemble those of Curculionidae: except in the group Platypides, where the body is straight and almost cylindrical, and terminates in an oblique truncation bearing a short hard spine.[155] FAM. 83. BRENTHIDAE.—_Form elongate; rostrum straight, directly continuing the long axis of the body, often so thick as to form an elongate head; antennae not elbowed._ The Brenthidae form a family of about 800 species, remarkable for the excessive {296}length and slenderness of some of its forms, and for the extreme difference in the sexes that frequently exists. It is well represented in the tropics only, and very little is known as to the natural history and development. These beetles are stated to be wood-feeders, and no doubt this is correct in the case of the majority of the species; but Mr. Lewis observed in Japan that _Zemioses celtis_ and _Cyphagogus segnipes_ are predaceous, and enter the burrows of wood-boring Insects to search for larvae as prey: they are very much modified in structure to permit this; and as the other members of the group Taphroderides are similar in structure, it is probable that they are all predaceous. Nothing whatever is known as to the larval history of these carnivorous forms. Indeed an uncertainty, almost complete, prevails as to the early stages of this family. Riley has given a sketch of a larva which he had no doubt was that of _Eupsalis minuta_, the North American representative of the family; if he is correct the larva differs from those of Curculionidae by its elongate form, and by the possession of thoracic legs: these, though small, are three-jointed. Descriptions, supposed to be those of Brenthid larvae, were formerly published by Harris and Motschoulsky; but it is now clear that both were mistaken. [Illustration: Fig. 150—_Eupsalis minuta_. North America. A, Larva; B, pupa; C, female imago; D, head of male. (After Riley.)]