ARMY OF INSECTS

Manawatu Standard, Volume LIII, Issue 23, 23 December 1932, Page 8

ARMY OF INSECTS

STEADILY BEING LIBERATED. TO PREY ON WHITE BUTTERFLY PEST. Numbering over 100,000, an army of insects which has been kept in cold storage and developed at Palmerston North during the winter is now ready for release to combat the steadily growing white butterfly pest. For months they have been under the care of Mr J. Muggeridge, B.Sc., at the Plant Research Station, and their home for the major portion of the period has been a small ice chest, in which they have, remarkably enough, thriven. The insects, whose proper name is Apanteles glomeratis, are members of the ichneumin family, and are an enemv of the white butterfly. LETHAL CHAMBER. Many are just now emerging from the cocoon stage and they have all been removed to the insectary which is located on the fields experimental area at Massey College. They have been under strict observation lor the detection of hyper-parasites which may have invaded their sanctuary anil which would, if left to survive, destroy the useful little colony on which scientific hope has been built. Two of the unwanteds keenly sought from among the insect parasites of the white butterfly are a particular species of ichneumin and also the clralcid, but so far only the former has been found. They have immediately been isolated and placed in special tubes, small size lethal chambers in which they are gassed or chloroformed. This is the scientific method of killing them.

Liberation of the parasites which are to attack the white butterfly has this season commenced, and they are being concentrated on an area at Maraekakalio, in the Hawke’s Bay district. This location lias been chosen because cruciferous crops, on which the white butterfly feeds are grown extensively there. Others are being liberated at places in a circle, so that they may converge on this central point. It has been stated that the white butterfly are not so noticeable in Hawke’s Bay' this year, hut scientific opinion inclines to the view that they are making their appearance later this year, and will he an invading host at the end of January, jeopardising particularly the survival of chou moellier crops. It was reported that during a recent hot spell there were literally millions of them round a crop at ono locality. However, this week 400 of their enemies have been placed among them and others are being reared as fast as possible to support the first division. ANOTHER BATCH RECEIVED. Kept m cold storage throughout the journey of the Kunguune, anoiner contingent of 44,000 or tlie Apantales insects came to hand at Palmerston North on Thursday from Faniham Royal, a centre m England where insects are developed for tlie Entomological Institute of tlie Empire, to be distributed throughout tlie world to combat pests. Tlie insects are reared under the supervision of one of the world’s leading authorities on the biological control of insects, and from there the Plant Research Station at this centre has from time to time received valuable consignments.

There is, however, to be a double attack launched on tho rapidly multiplying white butterfly; lor Teromalus puparum, a species of pupil parasite, will shortly arrive in scientific custody at Palmerston North. These will be used to attack the pupae of the butterfly while the Apanteles form themselves into the larval parasites. The new importation will not attack Tyria jacobaeae, tiie ragwort moth, which is dealing with the growth of ragwort. It is expected that they will be received in large numbers, as they breed readily under insectary conditions. WASPS NOT IMPORTED. Quite a lot of comment has been made about the importation of wasps. Two of the worst of this family have their home in Britain. They are Vesper vulgaris and Vesper sylvestris, while Vesper Germanica, Vesper llufa and Vesper Norwegica are also injurious, but the two fust named are slated to do quite a considerable amount of damage to fruit in Britain. “No one with the slightest knowledge of the subject or who had any responsibility in the matter wouid think of introducing these,” stated Mr Muggeridge. “The reports circulated to the effect that they are being brought into the country are entirely erroneous.”