WAYS OF THE WILD.

Auckland Star, Volume LXIV, Issue 147, 24 June 1933, Page 1 (Supplement)

WAYS OF THE WILD.

AN INTRODUCED WASP. THE ORCHABJDIST'S FRIEND.

(By A. T. PYCROFT.)

Mr. L. Weber, of Woodliill, Kaipara, writes as follows: "Will you let me know through your nature notes column the usefulness, or otherwise of a wasp called paper nest wasp. I find tlieni in large colonies in some big camellia trees, and I think that they are killing scale insects and spiders which are on the trees." The wasp referred to is an Australian, which was accidentally introduced into New Zealand nearly forty years ago, being first recorded from Hokianga. It is known to science as Polistes tasmaniansis, and is _ the orchardist's friend, as it is especially destructive to the pear leech, or sawfly, an insect which is now abundant all over New Zealand. The larvae or leech feed on the leaves of pear, cherry, hawthorn, plum, peach and other trees of the rosaceae. This wasp is now extremely common throughout the north, it is also to be met with on nearly all of the outlying islands north of Auckland, and it will no doubt increase in all localities where it is not checked by climatic conditions. It is known that other species of living wasps have been accidentally introduced into New Zealand, but they have not established themselves here. It has not, as far as I can ascertain, been proved that polistes has established itself south of Auckland, neither lias it been recorded as having reached the city, as the species is sub-tropical. Tauranga will probably be its southern This wasp tolerates no interference with its nest, its sting is most painful. I was stung twice on the neck when passing near a nest on one of the Chicken Islands. I was then forcing my way through a tall and thick growth of flax; my progress was considerably accelerated over scru'b covered boulders. The pain lasted for several hours, but there was no swelling or other after effects. Nests Built of a Papery Substance. The nests are built of a papery substance, and are beautifully designed. They are oval in outline and are built downwards from a slender stalk, the cells being arranged as in a honeycomb. The nests vary greatly in size, dependent on the number in the colony, and may be found as much as six inches or more in diameter. The old nests are, I believe, not used a second time, but the young brood are to be seen frequenting the roof of their nursery for some time after they are capable of flight. This wasp belongs to the family of social wasps vespidae (Latin vespa, a wasp). The well-known English wasp and hornet are also members of this family, which aro distinguished by the longitudinally folded wings, the highly developed social habit, and the presence of males, females (queens) and workers in each nest. Wasps are medium to large stinging hymenoptera, which are neither ants nor bees. The word hymenoptera is from two Greek words meaning membrane winged. This is one of the most distinct of all orders of insects, easily recognised by the stiff membranous wings, coupled together in flight by means of a series of minute hooks. Sawflies, ichneumon flies, ants, and bees also belong to this order. In most of the species the tongue is converted into an order for sucking honey, or other liquid food, and the mandibles are adapted for biting or cutting. In one large division including the bees, wasps and ants, the females and workers usually have a sting which is only a modified ovipositor, that is the organ with which many insects deposit their eggs. Dr. Tillyard, Australian Commonwealth entomologist, states: "Apart from the sawflies, of which there arc none in New Zealand, and a few obnoxious ants and wasps having a taste for fruit and household stores, this order must Ibo considered the most highly beneficial of all orders of insects. The unceasing work of the thousands of hymenoptera is the principal factor in the maintenance of the balance of jnsect life, whereby hosts of injurious species of beetles, flies and moths are prevented from over-running the world. The studies of the life histories of such forms, and the utilisation of their aid in checking introduced pests, is one of the cliief hopes of the future for economic biology.

Digging or Burrowing Wasps. New Zealand possesses thirteen species of these wasps. They are easily recognised by their long hind legs, by the smooth shiny body, and by their active predatory habits. They are also known as spider-hunters, on account of their habit of hunting about on the ground, tree trunks, etc., searching for

spiders, which they attack with great ferocity, and paralyse by stinging them in the nerve centre. They are then carried off to their burrows in the ground. The females have a very powerful sting, but I have not heard of any of these wasps attacking intruders as polistes does. Australia possesses over 400 species of flower wasps. None of this species occurs in New Zealand, but one species, it is hoped, will be acclimatised in New Zealand, where it will be of value in destroying strawberry grubs. This family of flower wasps is ono of the principal checks upon grass grubs in Australia. Male flower wasps fly rapidly in the sunshine. -The females, which arc entirely wingless, watch for them and catch hold of them with their long mandibles, and are carried off for a swift nuptial flight. When the females drop off on to the ground, they procecd to burrow in search of the scarab beetle grubs, on which tlicy lay their eggs. This is effected by stinging their prey into insensibility, and then laying the egg on the body of the grub, which is devoured at leisure by the wasp grub. Fourteen species arc known in NewZealand. Their habits are very diverse. Some make burrows in the ground, others build nests of clay. Some store their nests with spiders, others with flies, caterpillars, or even grasshoppers and cicadas. A common New Zealand name for those which construct nests in cracks ana crannies is mason wasp, or quite incorrectly "mason bee." A number of species are attracted to houses, where they will make nests in all sorts of places, key holes, behind bookshelves, and frequently in the folds of oilskin coats hanging up during the summer months, or in any suitable or concealed place. Pison sinolae is (lie commonest of the New Zealand species. It is black and may be seen during the summer months, when it is nest building, carrying a little ball of damp mud, all the time making a loud buzzing noise. Building operations last several weeks. Tlie nest consists of a single row of cells, in which the spiders «rc pla-.ed ;j> food for the grubs. Tlic.sc nests are sometimes sixteen inches long.