492 THE INVERTEBRATA 



antennae taper to a point and the frenular coupling apparatus is 

 common. The remainder forming the superfamily Papilionina may 

 be grouped for convenience as butterflies, whose antennae are clubbed 

 and on whose wings there does not occur a frenulum. 



Here are found the Whites, e.g. Pieris, the larvae of many of which 

 are restricted to a cruciferous diet, and the Blues and Coppers in 

 which the metallic colouring on the wings and the larvae tapering 

 towards both extremities are distinguishing features. There are also 

 the Swallow-tails, e.g. Papilio, in which the hind wings are commonly 

 extended into tail-like prolongations. Finally may be mentioned the 

 skippers, so-called because of their erratic darting flight quite distinct 

 from the sustained flights of other forms. 



Order COLEOPTERA (Beetles) 



Biting mouth parts ; fore wdngs modified to form horny elytra which 

 meet along the mid-dorsal line; hind wings membranous — folded 

 beneath the elytra — often reduced or absent; prothorax large and 

 mobile; mesothorax much reduced; metamorphosis complete, larvae 

 (see p. 457) campodeiform or cruciform or, more rarely, apodous. 



In the larvae the head is well developed (Fig. 318) and the mouth 

 parts are of the biting type, resembling those of the adults. The most 

 primitive larvae are those of the campodeiform type (found for instance 

 among the Cicindelidae (tiger beetles), Carahidae (ground beetles) and 

 the Staphylinidae (rove beetles)). They are very active in movement 

 and often predaceous, with well-developed antennae and mouth 

 parts, and chitinized exoskeleton. In the eruciform type (Fig. 318 B), 

 found among plant-eating forms like the lamellicorn beetles, the legs 

 are shorter, and the animal much less active in its search for food, 

 the body bulkier and cylindrical. Finally there is the apodous type 

 which is found in the Curculionidae (the weevils), in which not only 

 are the thoracic legs lost but the antennae and mouth parts are reduced 

 (Fig. 318 C). The apodous and eruciform larvae usually live inside 

 the soft tissues of plants or beneath the soil attached to roots. 



The relation which these larval forms bear to one another is indicated 

 by the larval stages passed through in the life history of the oil beetle, 

 Meloe, the larvae of which are parasitic on solitary bees of the genus 

 Andrena. The first instar is known as the triiingulin. This is an active 

 campodeiform larva which attaches itself to its host after searching 

 actively for it. The second instar which is enclosed with an abundance 

 of honey in the cell of the bee is intermediate in form between the 

 campodeiform and the eruciform types, legs being present, but very 

 small. The third stage is a legless maggot. From this series it may be 

 inferred that the form of larva in Coleoptera is related to the ease or 

 difficulty with which food is obtained. 



