Voracious Grasshoppers Cause Trouble

Press, Volume CIV, Issue 30822, 6 August 1965, Page 1

Voracious Grasshoppers Cause Trouble

The big appetites of mountain grasshoppers were making afforestation difficult above the natural timberlines of native beech forests, said Dr. Peter Wardle, of the Botany Division, Department of Scientific and Industrial Research, Lincoln, yesterday.

Dr. Wardle has been study- : ing the reasons for the upper ! limits of forests for the last i four years. He has been plant- 1 ing seeds and seedlings of both native and exotic species 1

above the timberline, but the grasshoppers have been eating the seedlings before they have had a chance to grow. To keep them away he has had to cover the little plants

with netting. Insecticides proved ineffective. “There are many practical problems in getting the seeds to survive long enough to make observations,” said Dr. Wardle, “and the large grasshoppers that inhabit the tussock country above the timberline have been the biggest problem of all.” To achieve comparable conditions at different sites, Dr. Wardle plants his seeds and seedlings in standard garden soil which he has to take with him up the mountainside. Fortunately, all of his seedbeds are accessible by vehicle. He has planted seeds and seedlings at altitudes between 3000 feet and 5400 feet, and in different degrees of shade. He has had results from one good season so far. “With native species,” he said, “it seems that the very young seedling is critical, and I have found that if you start with larger seedlings they will survive at least four years. Mine have been growing for four years and are still alive.” He has also experimented with exotic species, and some have germinated at the upper level, 5400 feet. “They are under snow at the moment,” he said. Similar work has been done in Australia, and this month Dr. Wardle will visit Tasmania and the high eucalyptus forests near Canberra to make comparative observations and collect specimens. The main purpose of his trip, however, will be to attend a conference of the Australia and New Zealand Association for the Advancement of Science in Hobart from August 16 to August 20.