George Vernon Hudson

“ Leaving its tunnel the insect rises to the surface, the thorax is lifted above the water which retreats from it on all sides, the skin cracks open at the back and the insect slowly extricates itself in a similar manner to the mosquito. In about ten minutes' time the wings are sufficiently hardened for use and the insect then flies ashore, but we may occasionally notice, beside their old pupa-skins, drowned individuals which have failed to effect a successful emergence. ”

“ The pupa (Fig. 2b) , is a most beautiful object, its anterior extremity being obtusely thickened and the limbs of the future insect quite discernible. On each side of the thorax the gills form a set of graceful plumes, a much smaller group being also situated at the extremity of its abdomen. In this state the insect remains almost entirely concealed in the burrows previously constructed by the larva, its gills imbibing sufficient air from the surrounding medium, and thus rendering ascension to the surface unnecessary. ”

“ The females hover over meat and other suitable substances, depositing a number of minute wriggling maggots thereon, not infrequently to the great disgust of some hungry individual, who perhaps is making his dinner off a mutton chop which the fly has selected as a home for her offspring. These larvæ are all produced from distinct ova, which hatch before being laid, as I have often proved, by removing them from the insect's abdomen, and watching the young larva emerge from a minute elliptical white egg, covered with a thin leathery skin. ”

“ The pupa (Fig. 5b) is very elongate, reposing in one of the burrows, previously constructed by the larva. It probably breathes by means of its spiracles, as no special organs of respiration are visible. The perfect insect appears in a short time, flying sluggishly in the sunshine, the female possessing an enormous abdomen, which almost incapacitates her for aerial locomotion; in other respects she resembles the male, which is the sex figured (Fig. 5) . ”

“ Among bees this is a most destructive insect, its larva being parasitic in their grubs, and thus greatly reducing the population of the hive, which is finally ruined by the wholesale destruction of its honey when the flies emerge. Driving the bees into a fresh box would, no doubt, be frequently beneficial in these cases, but it is to be feared that bee-keepers will have much difficulty in contending with this insect. Its sexes are readily distinguished by their size, the female being considerably the larger. ”

“ This opinion, however, is manifestly erroneous; the pupæ of the nemocerous Diptera are on precisely the same footing as those of the Lepidoptera, and it would be almost as reasonable to call one of these active, because it wriggles out of its cocoon in the earth before the emergence of the moth. The perfect mosquito emerges from a rent in the thoracic shield of the pupa, drawing each pair of legs out separately, and placing them in front of it on the water; the wings and abdomen are then extracted and in a few moments it flies away. ”

“ Every one who has walked in the forest at night has no doubt noticed, in many damp and precipitous situations, numerous brilliant points of greenish white light shining out from amongst the dense undergrowth. The animal which causes this light may be seen at Fig. 1a on the Frontispiece, and is probably one of the most interesting insects we have in New Zealand. ”

“ The perfect insects may be found everywhere, the males sucking honey from the flowers and performing many antics in the air, often clinging hold of one another and whirling about together. The female seldom flies, but is usually observed crawling about fences or the trunks of trees. She may be at once recognized by her heavy body which is very large when distended with eggs. Her general colour is dull red, thus differing widely from the male insect represented in the illustration (Fig. 5) .
Family Tipulidæ.
Simulia australiensis (Plate VI., fig. 1, 1a larva, 1b pupa) . ”

“ The water is periodically circulated in the tunnels by violent movements on the part of the pupa. About a day before emergence the insect assumes a peculiar silvery appearance, which is occasioned by the presence of a large quantity of air between the imago and its pupa skin. This air has been first imbibed by the gills and afterwards expelled through the spiracles of the enclosed gnat, thus inflating the skin of the pupa, and helping to buoy it up during its last and most important transformation. ”

“ Before emergence the anterior segments are projected nearly out of the cocoon from which the perfect sandfly makes its escape, and floating to the surface of the water ascends the stem of an aquatic plant to expand its wings. I should here remark that as with the mosquitoes, the bloodthirsty propensities of the present species have no doubt been acquired since the arrival of man and other warm-blooded animals. ”

“ A curious species, occurring occasionally in damp situations in the forest where it may be noticed leisurely walking over the leaves of various shrubs. It is very sluggish and may often be captured between the fingers without the aid of a net. Its life-history is at present unknown, but the larva probably feeds on fungi. The pretty little insect depicted at Fig. 11 may be found in similar situations but is not so common. ”

“ These larvæ are generally seen suspended from the surface of the water by the curious air-tube which takes its rise from the penultimate segment of the abdomen, which is of considerable length. Its apex is armed with a row of stiff bristles, which effectually prevent the water from entering the spiracle there situated, so that the insect is enabled to respire when hanging from the surface, independently of any muscular action. It is also worthy of note that the intestine discharges itself into this tube, an arrangement which does not exist among the British species. ”

“ When, however, the numbers of individuals of the same species are considered, it is probable that this Order includes a greater proportion of the insect-world than all the others put together. The preponderance of these insects over the rest holds good with greater force in New Zealand than in many other countries, and this fact may be almost inferred from the large number of spiders present here, which are chiefly dependent on Diptera for their support. ”

“ It is often mistaken by ignorant people for the mosquito and at once destroyed, but quite unfairly, as the species is in reality perfectly harmless, frequently benefiting mankind by the removal of considerable quantities of effete matter, which if allowed to remain could not fail to be injurious. ”

“ Coelopa littoralis (Plate VII., fig. 13) .
Extremely abundant on the sea-beach. Its larva feeds on decaying seaweed, burying itself in the sand before changing. The perfect insects often congregate in such vast numbers on some of the rocks that it is necessary to run past them in order to avoid being positively suffocated by the countless multitudes which fly up into one's face. This insect must be regarded as the New Zealand representative of the well-known dungfly of England (S. stercoraria) , which many of my readers will recollect has a similar habit of assembling in great numbers. ”

“ The air-tubes connected with these are distinctly visible in the abdomen of the insect, where they may be seen branching in all directions. When about to emerge this pupa works its way to the surface of the log, the head and thorax are thrust outside, and the perfect insect escapes in the ordinary way. The illustration (Fig. 2) is taken from a female; the male differs in being less robust, and in being provided with longer legs. ”

“ The perfect Rhyphus may be almost regarded as one of our domestic insects, and is seldom found in the open country, but frequents cowhouses and other farm buildings in great numbers, the larvæ feeding on the manure in these situations. ”

“ These take their rise from the mud at the bottom, and, extending upwards to a distance of three or four inches, afford the larva a convenient retreat from all enemies. These insects are occasionally seen swimming laboriously through the water with a peculiar zigzag motion. When out of their burrows they have considerable difficulty in keeping beneath the surface, and may be often observed floating helplessly with their exposed portions quite dry; in fact the whole integment of the insect appears to have a peculiar power of resisting the water. ”

“ When full-grown it slowly shrinks up and changes into the pupa shown at Fig. 3b. In this state it is not protected by any kind of cocoon, but lies amongst the refuse of the aphides, near the stem of the plant. The fly emerges in a fortnight or three weeks' time, and is very fond of hovering over and sucking honey from the flowers, but the females may be often noticed running about plants, probably in search of a suitable place to oviposit. [6] For an account of Scolobates varipes, a species parasitic on the present insect, I refer to page 39. ”

“ Its habits are, therefore, very varied. When parasitic in the Lepidoptera it usually selects the noctuæ, destroying a great number of many of the commoner species [9] . The infected caterpillars usually turn into chrysalides some time before the little maggots emerge, but this is not invariably the case, the parasite often destroying the larva at a comparatively early stage. The pupæ are buried in the earth, near the remains of their host, and are light brown in colour, with the segments much more distinct than is usual (Fig. 15a) . ”

“ The illustration represents the male insect, the female having a much stouter body, with short thick legs; she also differs in her antennæ, which are much less branched than those of the male.
Family Tipulidæ.
Rhyphus neozealandicus (Plate V., fig. 4, 4a larva, 4b pupa) .
A most abundant species occurring in most damp situations throughout the year. Its larva (Fig. 4a) closely resembles a small worm, being of an elongate form attenuated at each end. The skin is very hard and of a dull yellow colour, with black markings. ”

“ In some cases, where an unusually large gathering has occurred, a number arrange themselves into an outer row, their heads being immediately behind the extremities of the inner group, the whole thus bearing a rough likeness to the radiations of a star-fish. ”

“ The bites of these insects appear to distress some people much more than others, probably owing to constitutional differences. I should mention that the females alone engage in these attacks, the males being quite harmless and subsisting entirely on honey, which is doubtless the natural food of both sexes. ”

“ These flies are rather variable in colour, some specimens being dark brown, whilst others are more or less covered with greyish-white hairs; individuals are also often met with quite black and shining, their hirsute covering having been completely rubbed off. ”