Dominion Museum Notes UNPLEASANT INSECTS

Dominion, Volume 30, Issue 190, 8 May 1937, Page 2 (Supplement)

Dominion Museum Notes UNPLEASANT INSECTS

Parasites that Menace Public Health Of all insects which attack man, lice are the most common and the most repugnant. Infection of human beings by lice, though not unknown in New Zealand, is fortunately not common; but in the densely-populated slum areas of Old World cities the occurrence and spread of these insects constitutes a definite menace to the public health. The insects known as lice are small, flattened creatures, more or less oval in shape, and without wings, they all are parasitic on the bodies of warm-blooded animals, and fall into two distinct groups —the Mallophaga or biting lice, the_ majority of which occur on birds, and the Siphunculata, or sucking lice, which infest mammals, including man. There are now known to science about 1700 species of biting lice, and about 120 species of sucking lice.

Among sucking lice there are three species which affect mankind. All three forms may be present together on the same individual, and any form, when present, causes considerable discomfort to its host. The actual number of lice that may he harboured by a single individual is not known, though in all ordinary cases of infestation it must run into many hundreds. As many as 10,000 adult lice have been counted from a single shirt of an unfortunate soldier on active service!

The louse is entirely dependent on its host for its existence. Even the eggs must be laid in close proximity to his skin in order to secure a suitable incubation temperature. The female body-louse lays about 300 eggs at the rate of 8-12 per day. The eggs are encased in a chitinous shell and firmly fixed down by a sticky substance which quickly hardens. When eggs are laid in the hair this cement causes a matting together of hairs, forming what are known as “nits.” The formation of nits is characteristic of louse infestation, and is a dangersign calling for immediate attention

on the part of the infected person. In about seven-eight days’ time, under normal conditions, the egg hatches. The young louse does not differ markedly from the adult insect, and commences to feed immediately after hatching. The whole life cycle from egg to adult insect is complete, under favourable conditions, in about 16-1/ days. The adult lice live from threefive weeks, depending on the conditions under which they live. Head, and body lice are responsible for the transmission of more human diseases than any other insects. Typhus fever is the most deadly of these maladies. It is carried by lice, and lice only. A louse imbibing blood from a typhus patient can in 7-11 days transmit the disease to a healthy person. Au epidemic of typhus may reach appalling proportions. In Serbia, during February, 1915, the population declined at the rate of 500 deaths a day, due directly to typhus, or indirectly to lice. Relapsing fever also is transmitted by lice; and many skin troubles are spread by the same means. Lice, unlike fleas, do not infest buildings or haunte; they are spread only from one person to another by contact. Hence the importance of clean-liness-of body and clothing is at once apparent as the most effective means of combating the spread of these insects. Lice may be destroyed from clothing by heat or by chemicals; but dry heat, when applicable, is the simplest, easiest and most efficient means to employ. In the case of an infected person the

skin should be smeared' thickly with undiluted paraffin emulsion. This should be rubbed well into the hair. A hot bath and clean clothing should follow. In the entomological section of the Dominion Museum there may be seen illustrations and a brief discussion of lice. Filming - Eels. In connection with a recent series of educational lectures on Maori subjects at the Dominion Museum, the lack of suitable films illustrating Maori life was made evident. Through the good offices of Mr. R. R. Harris, of Hokio. arrangements were made for a film of eel fishing to be made in that locality, where the old methods of taking eels still obtain. Accordingly, two museum officers equipped with the necessary outfit visited tte locality recently and filmed the process of taking eels by trapping. Possibly this is the first time this Jias been attempted; and museum officials are alive to the possibility of capturing films of all activities of olden times before it is too late. From the start the

venture was a complete success, and an excellent series of pictures was taken. In the autumn months eels migrate to the sea to spawn. It is then that Maoris trap them in largest numbers. A converging fence of brushwood is built in the stream with the apex at which a trap is set pointing downstream. This trap consists of two parts, a lead oi poha, which directs the eels into a basket trap or hinaki. Eels are released by openiug a lid at the end of the basket trap. Rare Minerals. ( Mayor Island, in the Bay of Plenty, being an extinct volcano, has for long been regarded as an object of scientific interest, but recently it has been found to be a veritable treasure house of rare minerals. The Dominion Museum has been fortunate in receiving samples from the discoverer, Dr. P. Marshall, of the minerals Tuhualite, Reikeckite, and Aegirine. Of these, Tuhualite is a very rare and absolutely new mineral, found only on Mayor Island. The minerals Reibeckite and Aegirine, though comparatively common constituents of the earth’s crust, occur at Mayor Island in crystal forms which are found nowhere else on the face of the earth. Other objects of interest from Mayor Island, which also may be seen at the Dominion Museum, are pieces of larvas and obsidian or volcanic glass. Obsidian in reality is a larva which has cooled so quickly that crystallisation has not occurred, and the resulting product is a substance resembling glass in texture.