THE INSECT CATCHER.

Dominion, Volume 1, Issue 137, 4 March 1908, Page 2

THE INSECT CATCHER.

HOW HE WORKS. GOOD WORK ON THE CANTERBURY PLAINS. / The South Island has a monopoly cf' an insect treasure ' that preys., upon too blue gum, blighting it, olid causing it to die a prematuro death;, It is a scale inscct of exceeding minuteness,, but - it possesses this very largo name—eriococcus coriaceous. Under that title it deposits it-self upon .the. twigs of the blue gum treey—Nciv Zealand's most common eucalyptus— and, surrounded by a legion of its relatives, it sucks and sucks tilll the big treo' has been subdued and humbled and slam.' It is often the small things,of this world that possess 'tho'greatest'' power.' . -V Now, (the Canterbury Plains, before the advent; of tho white man, 'grew .no trees. And the early settlers, desiring shelter for tneir crops and timber for their many uses, planted largo areas of bluo gums.'; These throve and; gladdened the hearts of the men of the Plains, till one day eriococcus came round the corner; and with an 'irresistible onslaught changed tho landscape. Tho bluo gums of Canterbury were doomed. An appeal was in diio timo mado to that useful' officer, the Government biologist, Mr. T. W. Kirk, who sent his trusty lieutenant, Mr.- Cockayne,' to attack the devastating insect with an army of. ladybirds. What - a treasure is'the ladybirdl The particular regiment of ladybird used for this little war possesses a name almost as formidable as that of its foe. It is the: rhizobius veritralis.' It is a small black ladybird, without spots. We got it- from New South. Wales, its nativo home. Note, the opportunity for a" little lesson : about Nature' arid her beautiful methods! How rarely do we find a plant badly ,iiijured by pests', in its nativ-o'haunts !> The' gum. trees' aro natives of Australia. The ancestors of little eriococcus doubtless attempted, ages ago,- to 'get:afooting upon tho Australian gum trees, but,: as it developed, Nature also nurtured tho little- rhizobius to keep the. voracious crea-ture-down to reasonable limits.- It was a .master stroke, -and it preserved the.'balance of 'power. But when wo brought the gum treo to Now Zealand; wo brought, the scale insect with it, but left tho parasito behind.Wo thus upset the" balance of power; and eriococcus marched; forward to . undisputed Conquest;- ', heedless - of the despair of the treo .owners of-Canterbury and Otago. The biologist was appealed to, ■■ and .no doubt, according to the methods of the entomoloho .asked, himself two, or three simple questions.. What is the native,.land of the blue gum?. Does tho. pest.destroy;it there? If not, why not? From "Why not?" was evolved tho rhiiobius ladybird.. It was imported and liberated in,, the infected trees; Somo ladybirds seem ~to take life fairly easily,'-but tj(is ono was - apparently of: the pushful kind, for he has cleaned and saved the- trees of .the.- South. Island; ,Cockayne, assistant biologist, fl'ho went ; south last week to report progress, has declared the bluo gum blight, as a troublesome pest, to bo a thing of .the. past. . Rhizobius is, expected to include in his diet the scale insects of any of the-natural c-rder to which the blue gum belongs, as well as tho scale, insects-of 'some other plants.' ' Unfortunately Mr.-Cockayne has found that it does not inconvenience, to any. extent, tho mealy 'bug nor the. mussel 1 scale of tho apple, nor, indeed, any of those which cover themselves with. sufficient' completeness ;by a,.protective envelope. Tho mussel scale, for; instarico,: covers itself with, a 'coat which ,is impervious-to tho'Gvertures of the ladybirds', • but. tho scale of . the blue gum (has one ;vulrierablo spot in; his armour coat-,'--'and, -tho ladybird .finds. ;it; every, tinie.V. Entomologists, talk .of: scalo insects in two groups]- armoured and naked. , The;.'amour is' facturcd from the :old ' skins thrown off at moulting "times;', cemented together-;'.by ' matter excreted, from tho body. It-needs, somer thing with tho- strength of a beetle tb tear tiirni open. -•_ ' y." •'• :It is a - great .business,; this -eternal fight-' between. insect and ;in&cct.'.' "