White-butterfly Parasite.

New Zealand Journal of Agriculture, Volume 56, Issue 5, 20 May 1938, Page 344

White-butterfly Parasite.

SOME' concern has been expressed this autumn that the parasite Pteromalus, introduced to combat the white butterfly, has been responsible for biting human beings and causing swellings and discomfort in the region of attack. Fears on this score are groundless, according to the following statement which has been issued by the Entomology Division of the Plant Research Bureau : “ The white butterfly parasite does not come within the category - of a bloodsucking insect. It has mandibulate mouth-parts which, by their flexible attachment to the head, are adapted for feeding on a liquid. A blood-sucking insect has the mouth-parts modified into elongated organs that can be driven through the skin. Pteromalus only uses its mandibles for chewing its way out of the pupal shell of the butterfly. ' The parasite cannot bite anything as tough as the human skin. Also, it does

not sting, for its ovipositor is used for egg-laying. The. only members of the” Hymenoptera that sting are the ants, wasps, and bees, and these do not require the ovipositor as an instrument for placing the egg in a suitable position for the development of the larva. “ There is no evidence that'the insect attacks human beings in Europe, Britain, or America, where it has existed for many years. “We do not know of an instance of where' Pteromalus has been responsible' for biting any. person. None of the workers in this Division has received bites from it, even when allowed to crawl over the hands. When these parasites are being handled many of them would be in a very irritable state. ‘‘As a suggestion, it is possibly a Dipterous insect inflicting the bites. “ It is generally recognized, however, that insects of other species, particularly

sand-flies, which bear a certain general resemblance in the eyes of non-ento-mologists to the parasite of the white butterfly, can inflict stings and bites which may result in blood poisoning through injection into the human blood system of germs carried by the sand-flies or mosquitoes from some other source of infection.”

Spartina grass is to be found growing quite vigorously where it has been established by a neighbouring farmer on the. mud-flats of the Kaipara Harbour between Glorit and Kaukapakapa. Its growth is by far the best when planted on the softer mud areas. Where planted on the harder flats its growth is much slower. In the latter places it, however, is tending to build up to a height of about 6 in. a layer of soft mud and debris.