DESTRUCTION OF GRUBS

Grey River Argus, 25 August 1939, Page 10

DESTRUCTION OF GRUBS

MAJOR PROBLEMS. DUNEDIN, August 22. Dr. D. Miller, assistant director of the Cawthron Institute, and director of the division of entomology of the Research Department at Nelson, who is at present in Dunedin during his survey of the grass grub and grass caterpillar problems in Canterbury and Otago, made the following statement concerning his work to-night:— “The Government and the Cawthron Inst.tute are fully awake to the importance of the grass grub and grass caterpillar problem, and my southern visit is a preliminary to a conference with the Director-General I of Agriculture and the acting-secre-j tary of the Research Department m> Wellington on Thursday next. I consider that grass grubs and grass caterpillars constitute what can be looked upon as the major entomological problem of this country, since the foundations of our primary industries, that is pastures in jeopardy in that many thousands of acres of pasture land (at least 80,000 acres in the Ashburton County alone) have been re-1 duced to so much rubbish by these two insects this season, and most especially at a critical period of the year. . , “By this I do not wish to belittle in the least the almost equal influence I of the diamond-back moth and white; butterfly upon crops supplementary to the fattening of sheep. The latter insect, through the outstanding work of Mr J. Muggeridge, is under control from the farmers’ point of view, while his current researches hold considerI able hope of the former being eventuI ally subjugated. “The grass grub and the grass cat-, erpillar problems are not for the en-j tomologlst alone. They involve many, factors beyond his province, and con-l stitute one that demands team work; the association with entomologists of the fields staff of the Department of Agriculture the staff of the grass-; lands division’of the Plant Research Bureau, the field staff of the fertihsei industries, and the staff of those concerned with irrigation, where that is being developed. All of these I imd are deeply interested in the matter. From data al present available I think that control, or at least a sufficient measure of relief to the unfortunate farmer, will be found eventually in la practicable modification of faim practice combined with the introduc--1 tion and establishment of suitable I parasites. On the first I cannot offer lan opinion at the moment, as that I lies within the field of pasture and I farm ecologists, and not in that of enI t.oinologists; but in regard to the latI ter 1 might be permitted to offer an opinion, though I do not want to be swamped with letters from farmers asking the Cawthron Institute to send i a supply of parasites for an immediate solution of the problem. We cannot wave a magic wand. The work is a big job, and a long-range problem. “Both grass grubs and grass caterpillars are insects native to New Zealand. Consequently one looks first to what parasites attack these insects in (his country, and finding none, looks overseas to regions that are biotically most closely related, and where similar pests occur. With grass grubs we find that they have a free hand in New Zealand in that they are in no way subjugated by any insect parasite. In the case of grass caterpillars we find one or two native parasites which obviously have but little controlling influence. By looking fuithcr afield, we find that certain channels of profitable inquiry open up to us in Tasmania, as well as in other Pacific biotic relative the Chile-Pata-gonian region. In Tasmania there exists similar grass grub insects, and a, population of parasitic forms un-| known in New Zealand that jprey| upon grass grubs, but we in New Zea-| land know little at present of them. A somewhat similar insect to the grass caterpillar occurs in Tasmania: but like the caterpillar in New Zealand it. has a natural parasite that is ineffective. Indeed, we have sent our parasites to the Commonwealth, and, I fear, with little effect. I have had word, however, from Dr. J. Evans, the Tasmanian Government entomologist that he expects to visit New Zealand in November to discuss several insect problems of interest to both countries. “In the Chile-Patagonian region one finds both grass grubs and grass caterpillars strangely similar to those of New Zealand. During my expeditions to South America I naturally gave some attention to the subjects, and found that parasites existed there in the case of both types of insects. Being engaged at the time on piri piri (Bidi Bidi) insects, however, I was not able to devote detailed attention to a study of the problem, but nevertheless secured sufficient data to show the possibilities of the situation in so far as New Zealand is concerned. These are matters that will be dealt with at the Wellington conference on Thursday.”