IN TOUCH WITH NATURE

Otago Witness, Issue 4028, 26 May 1931, Page 24

IN TOUCH WITH NATURE

DETESTABLE INSECT. By J. Drummond, F.L.S., F.Z.S. Alany readers doubtless will regard the subject of this article, Cimex lectularis, as an unpleasant one, hardly fit for polite conversation. 'lt has been brought forward by an inquiry from Whangarei as to whether it is a native or a introduced insect. The correspondent gives it its popular name, the bed-bug. The answer to his question is that it came to New Zealand from the Old Country in the earliest days of colonisation, in vessels it infested. It is present in unpleasantly large numbers in parts of North Auckland. Decreasing in numbers further south, where the climate is cooler, it is lets plentiful in the South Island. “A blood-sucking parasite of mammals and birds, the detestable and all too common introduced bed-bug,” is Dr R. J. Tillyard’s description of it. While the bed-bug excites disgust, it belongs to a great order, the Hemiptera, which includes many remarkable and many beautiful forms. About 37.000 species of Hemiptera are known in the world. Of these, 1970 belong to Australia, some 300 to New Zealand Both countries have stilt-bugs, characterised by slender bodies, long legs, and elbowed feelers, burrower-bugs, shield-bugs, fungusbugs, assassin-bugs, lace-bugs, and leaf bugs, but no indigenous bed-bugs. All members of the order have "sucking beaks, designed only for imbibing fluids, either. the juices of plants, or the blood of animals. The beak is a long, jointed sheath, grooved. When not in use, it is folded out of the way on the underside of the body. Some members of the order, notably assassin-bugs, represented in New Zealand by four species, are beneficial to man. They prey on other insects, sucking their blood. A few species show the paternal instinct usually restricted to higher insects, such as ants, wasps, and bees. The Old Country has a species that lays between 3C and 40 ■P® B a time and mounts guard over them for several weeks, until they are batched. The female then covers them hke a hen covers her chickens. The shield-bugs—New Zealand has 10 species of them—sometimes are large and handsome, but most of them are noted for their horrid smell. The flat fungus-bugs live on fungi, and hide under bark or dead wood. . The Old Country seems to repudiate the atrocious bed-bug. “In this country at the present day,” Air E. Step, an English entomologist states, “it probably is only the poor that suffer from this pest, but in foriper times all classes knew it too well. Like some other insect annoyances, it is an introduction from abroad, but nobody can say which country is its proper home. It has been with us for about 400 years, probably entering our seaports in home-bound ships, and gradually extending from the circumference to the centre. Its wing s are not developed although there are vestiges of them. Possibly finding man with his ships and couches a good carrier to extend its distribution, it stopped developing wings, which were considered necessary no longer.”

Air Step states that in the Old Country many persons tolerate cockroaches in their houses, believing that the cockraches will protect them from the possibility of an invasion of bed-bugs. The belief, apparently, is well founded. There is a widely distributed bug, Reduvius per sonatus, one of the assassin-bugs, that flies into houses infested with bed-bugs and feeds on them. This may be a dangerous ally. . It is fond of human blood and sometimes finds people more attractive than bed-bugs. Its range extends from Australia to Europe, but it has not been reported from New Zealand. The bodbug’s greatest natural enemy in the Old Country is a little black ant. If it takes up its quarters in a house tormented by beg-bugs it soon clears them out. A somewhat peculiar feature of the bed-bug’s habits is that it has been found in only human habitations, perhaps on account of its taste for human blood. It is believed to be present only when the habitations have some degree of comfort and permanence, avoiding savage races. On the weather becoming too cold it is stupefied, reviving when warm weather returns again.

"* I note with interest your announcement that the smaller species of the cab-bage-butterfly bad been naturalised in Hawke’s Bay,” Mr W. W. Smith writes from New Plymouth. “In the first week of April, Alaster S. Aleyer, a young New Plymouth naturalist, visited Napier with his parents. During his stay there for two days he caught two specimens. Air Aleyer, sen., states that they saw at least 20 specimens in the district. The introduction of this insect adds another seriously destructive pest in New Zealand’s kitchen gardens. With the diamondback moth, it will increase the difficulty of growing good marketable and wholesome cabbages. In dry seasons in the North Island from New Year on, the diamond-back moth is very destructive to all the brassica and to the turnip crops and is difficult to cope with. The great annual expense of dealing with farm, garden, and forest pests—insects and mammals alike —is very serious to all engaged in the industries concerned.”

The diamond-back moth has distributed itself, by the unintentional agency of man, no doubt, over almost the whole world. It is very plentiful in gardens throughout the Dominion, its green caterpillars feeding on cabbages and other plants, and making small holes in the leaves. The Nelson province receives its particular attention. It is penetrated, even on to bleak Enderby Island, one of the Auckland group, in the Southern Ocean. In New Zealand the perfect moths appear from August to April. They are most plentiful in the late summer and in the autumn. They are more delicate in colour than handsome or showy. The expansion of their wings is only about half an inch. Their somewhat narrow fore-wings, as described by Air G. V. Hudson, are brown, often with

purple tinges. There is much variation in the depth of colouring of the forewings.

Entomologically, this insect is Plutella. cruciferarum. It has native New Zealand relatives, including a large, rare, handsome species, reported from the Hunter Mountains in Southland at between 3000 and 4000 feet above sea level, on the M'Kinnon Pass, and on Table Hill, Stewart Island. Another native member of the group lives in open country on mountain sides near the Otira River and on Ben Lomond, Lake Wakatipu, about 2000 feet above sea level. The native species, unlike the diamond-back, do no harm.

Air H. Cox, Tauwhare, Auckland Province, has described an incident at Pokeno to show how well shags can see. He saw a white-throated shag on a fence post. Its head was stretched up straight and it seemed to be watching something. Air Cox and bis sister strained their eyes but could see nothing. After about 15 minutes of absolute stillness —lie had not believed that it was possible for any living creature to stay so still—it suddenly left the post and swept upwards at a great speed. For some time the watchers failed to see anything in the air, but in a few minutes they saw another shag flying in the same direction in which the first had gone. Air Cox asks: — “ How long did the first shag see the second one? If the first one did not see the second one, how did it know that the second one was coming along? ” The first shag, he states, must have been on the post at least 20 minutes before be went towards it.

Air T. L. Alay wrote last month: “In a garden at the foot of Alount Wellington a month or two ago, song thrushes, blackbirds, skylarks, and chaffinches and occasionally goldfinches made life very cheerful. For the past six weeks not one has attempted to sing. It has been noted that the blackbird was singing for a shorter season than its song season m England. It seems that its companions in exile are following its example and at the time of writing not a single introduced songster is singing.”

The wild turnip, an introduced weed, often occurring in rich profusion in cultivated fields, and giving much trouble, is Sinapis arvensis officially, but it has no fewer than 56 popular names in the Old Country. In New Zealand it is sometimes called charlock, yellow weed, and wild mustard. A resident of Riccarton. near Christchurch, asks if, in New Zealand, it is ever called brasslock. He states that- in—the Isle of Man, of which he is a native, it is never called anything else. When he came to New Zealand many years ago he saw on a farm large quantities of this weed. “ You have plenty of brasslock in your cornfields,” he said to the farmer, who replied: “That’s not brasslock, it’s wild turnip.” Amongst its other names are chedlock, codlock, skellock, warlock, birdseed, popple, presha, and runch.