NATURE NOTES

New Zealand Herald, Volume LXXII, Issue 22030, 9 February 1935, Page 1 (Supplement)

NATURE NOTES

BY J. DRUMMOND, F.L.S., F.Z.S

,THE COMMON FLEA

When, the Adventure, on Captain Cook's second voyage, 161 years ago, put in at Queen Charlotte Sound, a party of sailors, wandering into a deserted pa, found the place swarming with fleas. This was accepted as evidence that Maoris had abandoned the whares not long previously. As most people who have spent a night in an old deserted Maori whare know fleas' presence in great force was evidence in the opposite direction. The incident is explained by fleas' life-history and habits. They begin life's pilgrimage as an embryo in a white, waxy, oval egg. The next stage is a wormlike, eyeless, bristly, legless, whitish, wriggling grub. It breaks its shell with a sort of tooth on top of its head. Coming out, it lives in dust, and searches actively for food among refuse. The activity soon ceases. The grub makes a cocoon of spun silk and dust. It rests inertly inside and becomes a chrysalis. A perfect flea, emerging from the cocoon, demonstrates the complete .metamorphosis that characterises the higher groups of insects. This strange process is highly developed in the flies, the Diptera, and fleas, although wingless, are fairly closely connected with the flies.

The association between the common flea's life-history and deserted whares lies in the fact that while fleas ar« resting in their cocoons beneath floors or in cracks, waiting to be called to the final stage, they are extraordinarily sensitive to vibrations. Many observers, have noted this peculiarity. The best account is given by Mr. J. Waterston, a member of the Entomological Department of the British Museum, in " Fleas," an informative and useful little museum publication that can be placed on the bookshelf of any home for fourpence, value in relation to price that few other publications equal. Mr. Waterston draws attention to the experiences of people who enter houses left empty for a long time. These people sometimes complain that hordes of fleas appear suddenly. Fleas in cocoons have responded to vibrations caused by the people moving about. The moisture and the quietness of empty houses induce an increase of fleas, but check their distribution, which breaks out in force at every opportunity.

The same thing, observed with the bird flea, a different species from the common flea, may occur in most other species of fleas, which are many, numbering about five hundred. Mr. Waterston, to prove his conclusions, picked up cocoons that showed dark against the light, and placed them gently on a card, which he- tapped sharply. In most cases the fleas immediately came out of the cocoons. Dr. David Sharp, whose work on insects in " The Cambridge Natural History " delights students, wrote: " Enormous numbers of fleas sometimes are found in uninhabited apartments to which animals previously had access. These fleas, in numbers and with great eagerness, will attack any unfortunate person who enters one of the apartments."

I„ y - A female of the common flea may lay, at intervals, as many as 450 eggs. The numbers of individuals at times are countless and appalling. A steady stream of grubs and adults was seen falling from a cracked ceiling in a house in England. The eggs had been laid on the upper surface of the ceiling. Charles Darwin spent Christmas, 1835, at the Bay of Islands. There he saw the brown rat, which he confessed in his journal he was forced to own as a countryman. He did not complain of fleas, but earlier in the same year at Valdivia, in Chile: " Our restinghouse was so dirty that I preferred sleeping outside. On these journeys the first night is generally very uncomfortable, because one*is not accustomed to the tickling and biting of the fleas. I am sure that in the morning there was not a space on my legs of the size of a shilling that had not its little red mark where a flea had feasted."

The common flea, Pulex irritans, is almost cosmopolitan. Arid deserts are among the few places it does not favour. There is not complete supportfor a theory that it was first brought to New Zealand in Captain Cook's vessels on his first voyage in 1769, and that before his arrival New Zealand was devoid of fleas. The theory may be sound, or it may not. If it is, New Zealand was an exception and is a shocking example of the common flea's capacity to increase in a new country. It soon filled pas {tnd villages and found suitable breeding-places in warm sandy places in the North Island. About seventy-five years after Captain Cook's first voyage a distinguished visitor pitched his tent in the open on the bank of the Waikato River. Dread of fleas deterred him from camping in the pa. The Maoris, who called them pakeha, said that they were introduced by Europeans, a statement made at an earlier date by J. L. Nicholas, who accompanied Samuel Marsden.

California's reputation as one of the worst places for fleas was given probably more in jest than in earnest. It dates back to the Spanish occupation. Indian homes were alive with fleas before Spanish people settled there. Further than this, the flea's Californian history is unknown. Fleas entered into the Indians' lives and legends. Nobody troubled to collect this information, which disappeared with the tribes. As miners surged over the Great Desert and the Rockies in "the forty-nine," a clergyman produced a drawing of a lively flea-liunt in a Californian lodginghouse. and warned every man not flea-proof to shun Indian villages and old Spanish towns. The species was the sames species as occupies New Zealand. It is still the dominant species in California outside of the thickly populated San xFrancisco Bay district. The latest report, in "A History of Ejntomology," by Professor E. O. Essig, of the University of California, is that fleas are not in the least troublesome in that State now wherever proper measures are taken against thein. During twelve years' residence in Berkeley, Professor Essig seldom had a flea in his house. Of 10,972 fleas examnined from San Francisco, only 5.57 per cent were Pulex irritans.

The European rat flea, one of the carriers of bubonic plague, but not the most neii.nous, may be common on rats in New Zealand, the late Hon. G. M. Ihomson discovered in his inquiries. Twelve years ago he was told tliat it was found on many rats examined in Wellington Hospital. The dog flea and the cat flea are present in largo numbers. The mouse flea occurs on New Zealand mice, black rats and brown rats. The bird flea is present on fowls. The rabbit flea has not beeft recorded in New Zealand. The common flea has been found on all sorts of animals. Species that favour lower animals bite human beings. Cats in England, after hunting rabbits, returned homo swarming with rabbit fleas. Diverse in spec:es, multitudinous in numbers, fleas no longer are despised. Sir J. Arthur Thomson admired them. He declined to call them parasites, preferring the term beasts of prey. The safest plan is to dread them as a menace.