LEAF MINER

Hauraki Plains Gazette, Volume 58, Issue 4108, 4 March 1949, Page 9

LEAF MINER

DESTROYS RAGWORT HAS STRONGER PARASITE The leaf miner, which has been known to mine ragwort leaves for some time, is definitely useful in reducing th,e vitality of the plant but owing to the high percentage of parasitism it can never be regarded as being a vital factor in the control of ragwort. This advice was given the Ohinemuri County Council by the Plant Diseases Division of the Department of Scientific and Industrial Affairs after some ragwort leaves on which there were several grubs had been sent to the division.

The parasite is * slightly smaller insect than the leaf miner itself and more active. It can be easily distinguished. from the miper by the fact that it has four wings, while the miner, being a true fly, has only two; the parasite has relatively long antennae which are constantly vibrating up and down as the insect is walking and its body is jet black. The county clerk, Mr A. A. Jenkinson, stated that when he sent the specimens to Auckland he had no idea there were parasites on the leaves. Council employees at Tirohia had noticed that hundreds of ragwort plants had been affected by this fly, most of the leaves turning brown and appearing to die. The small grub, which was hardly half an inch long, had gone into the chrysalis stage. Samples had been sent to Auckland and the foregoing reply received.

** ft does not look as if it is going to eradicate ragwort,” commented Mr Jenkinson.