A LUCERNE SEED PEST.

Wanganui Chronicle, Volume LXVI, Issue 7567, 10 May 1919, Page 8

A LUCERNE SEED PEST.

In a recent number oi the Agricultural Gazette of JNew boivth Wains'' is a report on chalcid wasps jn Jucerno seed, und as this pest was introduced into Sew South Wales from the (jniter] !State« in imported lucerne seed there is naturally a danger of its introduction j into Ntv. Zealand. Mr. VV. VV. Frogi gatt, the Government entomologist, ( states that it lias for some years past gfeatjy reduced the yield of lucerne seed j in the Tamworth district. It was first noticed at Pailamallawa about threo years ago; and lor tlie last two years lias increased very rapidly, doing a great deal of damage. The tiny black wasp punctures the immature seed and deposits her eggs beneath the skin, under the protection of which the. baby larvae wasp feeds, grows, and finally pupates. The perfect wasp emerges from the pupa by cutting a hole through the skin of tiie lucerne seed. At the time of his visit no wasps could be found about the lucerne flowers, but any waste seed in the thresher or sheds contained a percentage of parasitised seeds in the pupal form, from which the perfect oarasits were at any tinio read}' to emerge. Experiments carried out by the lucerne growers have shown that if the first .summer cuit is burnt, the next cut <:an bs allowed to rippn lor seed. Mr. Froggsitt is of opinion that if the first cut i-i made before the seed is more than half grown, and allowed to dry for lucerne hay, it will not be necessary lo burn it, as the immature wasp larvae will die as the seed withers in the hay. making. A misapprehension which has arisen is that the chalcid wasp attacking lucerne is identical with that vhich is hi-mr distributed by the Department to sheopowners in the campaign against sheep-niasgot flies. Except that both wasps belong to the family of Chalcididae, of the order Hymenoptera, they are quit'? distinct species. They are f"rtlip** clistinr-t from tb» fact that while the plant-eating chalcid wasp never touches animal matter, the sheep-mag-got eKalcid wasp never touches vegetable matter, the latter confining her attention to the pupae of blow-flies.