_Vespoidea._--This section includes a number of families characterized by the backward extension of the prothorax to the tegulae and distinguished from the ants by the absence of "nodes" at the base of the abdomen. The true wasps have the fore-wings folded lengthwise when at rest and the fore-legs of normal build--not specialized for digging. The _Vespidae_ or social wasps have "queens" and "workers" like the ants, but both these forms of female are winged; the claws on their fret are simple. In the _Eumenidae_ or solitary wasps the female sex is undifferentiated, and the foot claws are toothed. (For the habits of these insects see WASP.) The _Chrysididae_ or ruby wasps are small insects with a very hard cuticle exhibiting brilliant metallic colours--blue, green and crimson. Only three or four abdominal segments are visible, the hinder segments being slender and retracted to form a telescope-like tube in which the ovipositor lies. When the ovipositor is brought into use this tube is thrust out. The eggs are laid in the nests of various bees and wasps, the chrysid larva living as a "cuckoo" parasite. The _Trigonalidae_, a small family whose larvae are parasitic in wasps' nests, also probably belong here. The other families of the _Vespoidea_ belong to the series of "Fossores" or digging-wasps. In two of the families--the _Mutillidae_ and _Thynnidae_--the females are wingless and the larvae live as parasites in the larvae of other insects; the female _Mutilla_ enters bumble-bees' nests and lays her eggs in the bee-grubs. In the other families both sexes are winged, and the instinct and industry of the females are among the most wonderful in the Hymenoptera. They make burrows wherein they place insects or spiders which they have caught and stung, laying their eggs beside the victim so that the young larvae find themselves in presence of an abundant and appropriate food-supply. Valuable observations on the habits of these insects are due to J. H. Fabre and G. W. and E. Peckham. The prey is sometimes stung in the neighbourhood of the nerve ganglia, so that it is paralysed but not killed, the grub of the fossorial wasp devouring its victim alive; but this instinct varies in perfection, and in many cases the larva flourishes equally whether its prey be killed or not. The females have a wonderful power of finding their burrows on returning from their hunting expeditions. Among the Vespoid families of fossorial wasps, the _Pompilidae_ are the most important. They are recognizable by their slender and elongate hind-legs; many of them provision their burrows with spiders. The _Sapygidae_ are parasitic on bees, while the _Scoliidae_ are large, robust and hairy insects, many of which prey upon the grubs of chafers.