Next to Polistes, Vespa is the most numerous in species, about 150 being known, and it is to this genus that all our British social wasps belong. No Insects are better known in our islands than these wasps, owing to the great numbers of individuals that occur in certain seasons, as well as to their frequently entering our habitations and partaking of our food, and to the terror that is occasioned by their supposed ferocity and desire to sting. This last feature is a complete mistake; wasps never sting unless they are roused to do so by attacks, or by considerable interference with their work. The only real danger arises from the fact that a wasp may be occasionally taken into the mouth with fruit, or may be handled unawares. When they are flying about they are perfectly harmless unless attacked or irritated, and even if they settle on the person no danger of their stinging exists unless movement is made. Sichel correctly states that a person may station himself close to a wasp's nest and remain there without any risk at all, provided that he makes no movement; indeed, it is more than probable that if no movement, or if only gentle movement, be made, the wasps are unaware of the presence of an intruder. It is, however, well ascertained that if they are molested at their work, more especially when they are actually engaged in the duties of the nest, they are then extremely vindictive, and follow for a considerable distance those who have irritated them. The East Indian V. velutina is specially fierce when aroused, and is said by Horne to have followed a party through dense jungle for miles, and on some occasions to have stung animals, and even human beings, to death.
Fig. 34—Ischnogaster mellyi. Java. A, Female imago (the line at the side shows its length); B, nest, C, maxilla; D, labium; E, mandible (tip downwards). The nest is probably upside down, although shown here as by de Saussure.
This vindictiveness is, however, only an exceptional mood due to some interference with the colony. Even the hornet, notwithstanding its threatening appearance, is harmless unless unduly provoked; its nests and their inhabitants can be kept in domesticity, exhibited to strangers, even moved from place to place, yet the hornets will not take offence if due gentleness be observed. It is said that wasps will rear the progeny of a neighbour in circumstances where this assistance is necessary. Hess has related a case in which a queen-hornet had commenced a nest, and was killed by an accident, leaving young brood in the comb unprovided for: as a result many of the helpless grubs died, and others were in a state of starvation, when a strange queen-hornet appeared, associated itself with the comb, and, adopting the orphan brood, nourished them and brought them to their full size.
We have already alluded to the fact that, so far as external structure is concerned, there is no great difference between the social and the solitary wasps. Both, too, run through analogous series of forms and colours, and the genus Ischnogaster (Fig. 34) seems to connect the two groups by both its structure and mode of life. The social habits are in many species only inferred, and with greater knowledge will probably prove fallacious as a guide to classification; indeed we have already said that in the genus Vespa—perhaps the most perfectly social of all the wasps—there is one species that has no worker, and that lives, it is supposed, as a parasite, in the nests of its congeners. For this species, V. austriaca, it has been proposed to create a separate genus, Pseudovespa, on account of this peculiarity of habit, although no structural character has been detected that could distinguish it. De Saussure has stated his conviction that workers do not exist in some of the exotic genera, so that it appears highly probable that with the progress of knowledge the present division between social and solitary wasps will prove untenable.
Remains of Insects referred to the genera Polistes and Vespa have been found in tertiary strata in various parts of Europe and in North America.
Fig. 35—Masaris vespiformis. A, male; B, female. Egypt. (After Schaum.)
Fam. 3. Masaridae.
Anterior wing with two complete sub-marginal cells. Antennae usually incrassate or clubbed at the extremity. Claws distinctly or obsoletely dentate.