IMPORTED INSECTS.

Poverty Bay Herald, Volume LII, Issue 17008, 15 April 1926, Page 8

IMPORTED INSECTS.

DAMAGE WORKED 15V PARASITES THODSANDN OF POI NDS LOSS.

The influence of insects on progress formed the subject of ;m address to the members of the Palmerston North Lunch Club on Tuesday by Mr. 1). Miller. Government entomologist. Mr. ..I. Murray presyded over a good attendance. In his opening remarks the speaker went hack to the early days of New Zealand. when the vegetation and animal inhabitants of the country were unique and very unlike anything in (lie Old World. However, with both introduced plants and flowers, many of the parasitic animals (worms and insects) naturally infesting them were also established so that to-day we had to contend with numerous destructive parasites, most of which were foreign to New Zealand, though a few of lho native insects, at the same"time, had become destructive. The significance of the attacks ot these parasites on domestic animals and plants was not fully realised, since most of the parasites were obscure, but their presence was a constant drain on the vitality of their hosts, the productivity of which was consequently' inhibited. Farmers had. therefore, to contend with parasitic insects which attacked their stock and vegetation. IMPOSSIBLE TO’ EXTERMINATE. Ju a state of nature no parasite was injurious; each has its use in checking the abnormal development of the animals or plants infested, all of which naturally supported a. certain population of parasites which had to-become abnormally abundant to impair the health of their hosts. A parasite became injurious only when its activities reduced the market value of man’s products, it was impossible to etxcrminate these parasites, and it only remained to keep them on the defensive and so keep them, as much as possible, from spreading, the damage caused stock and vegetation amohnted to millions of pounds, the speaker giving instances of the effect of flies on sheep. The cost of keeping animals under constant- observation and treating them when affected worked out at about Is 6d a. head, he said, while if all the sheep in New Zealand were attacked by this fly the cost would amount to lj millions sterling annually. Actually the control, of these Hies throughout the country amounted to £11)0,(XX) annually. THE. CATTLE TICK.

The cattle tick was another menace, and while there were no figures available, its ravages were appreciable. The tick was mainly confined, to the North Auckland peninsula, and it had been ascertained that one tick sucked a teaspoonful of blood , during its lifetime (one year), so that when a thousand or so of these ticks attacked an animal the extent of its depredations could be imagined. Then there were parasites which attacked agricultural crops, the culprits in this connection being beetles, which caused an annual loss in •Southland alone of £5(1,000. Another species was a midge, which caused a loss over an area of 500 or 400 acres of £6OOO annually. ■HUM TREES SCALE. In passing on to deal with the gumtree scale, the speaker said its method was similar to that of the mosquito, and that it punctured the hark of the tree, sucking the sap, and causing the tree to turn black and die. The scale was a native of Australia and was introduced into New Zealand through ironhark poles which were imported from Australia to Timaru in the year J9CO. From there the scale rapidly went through the Canterbury district, and then to the North Island—in the latter connection it was thought by Way of the southwesterly winds. The value of the gumtree plantations in New Zealand was approximately one million sterling, and thousands of pounds worth of damage was being caused throughout the country by the work of the scale. At the present time, owing to the introduction of poles from Australia for power reticulation purposes in New Zealand, various kinds of insects were being given every opportunity to spread owing to the fact that they attached themselves to these poles. However, a remedy had been found in the black ladybird, winch had so controlled scale" that the .gum-trees in Haivke's Bay were now just as healthy as they were before the scale found its wav to these shores.