164 The Orders of Insects 



Order 15. Hymenoptera (Sawflies, Gallflies, Ichneumon-flies, 

 Ants, Wasi's, Bees). — Insects with four similar membranous 

 wings, of which the front pair are the larger. Mandibles 

 present. The first abdominal segment joined to the thorax. 

 Kidney-tubes many. Complete metamorphosis ; larva; eruci- 

 form. 



Various groupings of these orders into larger 

 divisions ("super-orders" or "sub-classes") have 

 been proposed. All insects with biting jaws — such 

 as Orthoptera, Coleoptera, Hymenoptera — are some- 

 times united together as Mandibulata, while those 

 with sucking or piercing mouth-organs — such as 

 Hemiptera, Lepidoptera, Diptera — are classed as 

 Haustellata. In other arrangements greater stress 

 is laid on the nature of the life-history, those insects 

 hatched in a state like their parents being styled 

 Ametabola, those with a distinct larval, but no rest- 

 ing pupal stage Hemimetabola, and those with such 

 a pupal stage Holometabola. In the synopsis just 

 given, orders l-J are Ametabola, 8 and 9 Hemimeta- 

 bola, 10-15 Holometabola. Another system of nomen- 

 clature indicates the nature of the jaws both in the 

 nymphal or larval and in the perfect stage. Insects 

 which have biting jaws throughout life (e.g. Coleoptera) 

 are Menognatha, those with sucking jaws throughout 

 life (Hemiptera) are Menorhyncha, while those with 

 biting jaws as larvje and sucking jaws as imagos (e.g. 

 Lepidoptera) are Metagnatha. It has also been pro- 

 posed to lay stress on the kidney-tubes, whether they 

 be many (Polynephria) or few (Oligonephria). The 

 first two orders — Collembola and Thysanura — have 

 been separated, as Apterygogenea, from all the rest 

 (Pterygogenea), their wingless condition being re- 

 garded as an ancestral character, whereas wingless 

 insects in other orders are evidently degraded forms 

 (96). These various divisions are merely mentioned 

 for the present. They raise questions of high interest 



