GOLDEN SCALE

Nelson Evening Mail, Volume LVI, 14 November 1922, Page 7

GOLDEN SCALE

ITr i the Editor!

Sir, —I am glad to see that Dr. Tillyard has replied to my letter, and, as far as he was able> given an answer to my questions. Still it appears to me that We are both receiving from Christchurch statements that when placed side by side, appear to be very contradictory. As tin old Christchurch boy, I am perfectly familiar with both the town and (lie surrounding district, besides having many friends from whom I can seek information when 1 require it; yet strange to say I have yet to hear of any trees that have been killed by the scale. Perhaps Dr. Tillyard would be so kind as to inform mo whether it is the large trees belonging to the Domains Board 'that are being killed, or the young trees under the control of the Selwyn Plantations Board ; if it should be the latter, I hen their death might easily he due o other means. I was certainly quite unaware that Dr. Tillyard was only called in after every other expert had failed. There was certainly no mention made of this at the Domains Board meeting when the question of scale infested oaks came up. for discussion. It was Mi Stead who stated that he had been corresponding with Dr. Tillyard on the subject, and at the meeting he moved a resolution that three sacks of infected oaks he forwarded to <l,c ri^ wL ’ 3 , nrl stitute, in order that Dr Tillyard might experiment with the scale and hud out if there was any natural parasite. Ibis meeting took place somewhere about, i believe, March or April of the present year, and it certainly seema strange that’Mr Stead should move such a resolution after a correspondence with Dr. Tillyard, unless the Dr. was at the tim.. quite unaware that the scale was present in the Nelson district, and had been for the last 50 years. Moreover, it was not till some months later that Di. id • yard wrote to say that ho had sent specimens both to England and America and bad them identified. It seems strange that ho should have wasted so much lime, in writing so far, whet, a letter to tiie Department of Agriculture at Wellington, or myself at Riwaka, could have .riven him all the necessary information, besides, when 1 saw the Dr. last Maub, I offered to identify any scale insects for the Cawtbron Institute when required, for the more love of the work 1 'yd certainly give Dr. Tillyard credit for doing his best to save the trees, but be lias still to convince me that the trees require saving, as I have slated hcfmo, the information received by me is very different from that winch Dr. Tillyard Stales he has received, and until be can convince me that I am wrong, it is only reasonable to think that I should he guided by the knowledge gamed m my 14 years’' study of the scale insects-a study in which I have at least 12 years advantage of Dr. Tillyard. As regards the pvogoiiv of parasitised scales being lessened in' number, will Dr. Tillyard (ell mo whv the scale insects in New Zealand and elsewhere, which are the most heavily parasitised, arc also the most plentiful? Surely Dr. tillyard is joking when he makes a comparison between the rose scale on the blackberry and the San Jose on the apple. Any fruitgrower of intelligence, would tell him that the apple tree is living under forced conditions, and therefore tho slightest thing is likely to upset its balance; whereas the blackberry is living in a state of nature, and can stand many a hard knock without suffering ill effects. I am quite aware that the Indian cochineal insect (dactylopius indicus) is said, many years ago, to have killed down all the wild cactus plants in the Jaflnn Peninsula. These plants wore doubtless opuntia monacantha, which is the natural food plants of this species. Why is it that the same scale insect is still found badly infesting the same species of plant in'the same district at the present time? That the Australian entomologists have been unable to rear it in any number on opuntia iutorniis is not duo to the action of parasites, but simply to the fact that this species is rarely found on any species of opuntia other than monacantha. The same thing may ho said of tho golden scale: it will infect no other plant except the oak, even though other plants may be growing immediately beneath the spreading branches of the infested oak. This is not an isolated example, but the same thing may he found among many species of scale insects, and (his fact goes far to make the study of this family so interesting. As to why I mentioned the tit family in my first letter. I may say that it was because it was the only reference I could find of anything that destroyed the scale, and at least t\») authorities of the Coccidae in England were of opinion that it went a long way towards keeping down tho scale in that country. We have in this country the “White Eye” or “Blight bird” so common in this district; is it responsible for keep'mg down the scale in Nelson? In conclusion, I would say to Dr. Tillyard, go ahead with your parasites, hut .don’t let it blind your eyes to other means. There are other ways of attacking scab; insoefs than parasites, birds, spraying, or fumigation : there arc also fungoid diseases which attack scale insects in a similar manner in which certain catterniliars are attacked. Trusting that this letter will not he found too long.—l am, etc., G. BRITTTN. Riwaka, 10/1.1/22. A