BUTTERFLY PEST
PARASITE GAINING ASCENDENCY ENCOURAGING REPORT By Telegraph- Presr Association PALMERSTON N., March 10. Farmers throughout the Dominion will be encouraged by the report of Mr C. J. Hamblyn, fields superintendent of the Department of Agriculture, that the parasite liberated to reduce the white butterfly is showing definite signs of victory over its host which has multiplied so rapidly this summer. About three weeks ago in the Mount Stewart district it was possible to collect large quantities of butterfly chrysalids, and if the parasite had not been present these would, within a few days, have hatched out as adult butterflies ready to play their part in multiplying the pest. The parasite was present and could be seen at work laying eggs in these chrysalids, but considerably more than 50 per cent, of the chrysalids had not been attacked and therefore would produce butterflies. However, an inspection made a few days ago revealed a vastly different state of affairs. Thr parasite had apparently increased remarkably in numbers and it was estimated that up to 90 per cent, of the chrysalids had been parasitised. This was demonstrated by the collection of some 500 chrysalids which were removed and confined under glass. After three days only five butterflies emerged, whereas hundreds of parasites made their appearance. “It is more than probable,” said Mr Hamblyn, "that throughout the Southern half of the North Island where the white butterfly is continually reported to be doing considerable damage to crops of the turnip family, the parasite is present and the same state of affairs as found in the Feilding district applies. This being so. it is not likely that further liberations of relatively small numbers of parasites will do any good at this stage. Farmers interested will be well advised to make a small collection of chrysalids, place them under glass and watch for the proportion of parasites hatching out to butterflies. The failure of the parasite to overtake the butterfly in the early part of the season has not yet been accounted for. The possibility of this parasite actually being reduced by a parasite of its own has not been overlooked by Mr J. Muggeridge, entomologist to the Cawthron Institute, where the work of breeding the parasite is being done, but up to the present nothing of this nature has been found.” It would appear that the exceptional weather conditions last summer and autumn gave the parasite a greater check than the butterfly, and from very small numbers at the beginning of the season it had taken some time to increase to the extent of overtaking the butterfly which had everything in its favour for some months. In all cases where control of an insect pest was maintained by a parasite there was a fluctuation in the efficiency of control to an extent that occasionally the pest increased enough to do considerable damage.
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Bibliographic details
Timaru Herald, Volume CXLIV, Issue 20983, 11 March 1938, Page 5
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479BUTTERFLY PEST Timaru Herald, Volume CXLIV, Issue 20983, 11 March 1938, Page 5
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