THE SPIDER FLY.

Otago Witness, Issue 1942, 7 February 1889, Page 35

THE SPIDER FLY.

During the last three weeks I have continued my investigations into the habits of . the spider, of, as it is sometimes called, mason fly, and am forwarding specimens for the benefit of those interested. • j There is I am informed, another fly of somewhaf ffce same habits, but of a red colour. This member of the species preys not upon the^garden spider, but upon the large black one that lives in holes, commonly ! called the wood spider, It may be seen chasing these spiders along the ground or on fallen trees, and to use the words of one of my informants, " hunting them as a dog would a pig, evidently following its prey by scent Both the species are furnished with long and apparently remarkably sensitive antennae. As far as I have yet ascertained the red fly does not build a clay nesfc like its black relative. The strength of these flies must), in proportion Tto their "size, be immense, as I have frequently seen one of them carrying a spider fully three times its [own weight. The egg of the mason fly when first laid is a little larger than a pins head, and is generally attached to the body of the first spider placed in the nest. In a few days it will have attained the size of a grain of rice, and' then begins to show signs of vitality, presenting the appearance of a small caterpillar. Each spider in the nest has now in succession to afford nourishment to the young grub, which leaves the skeletons in the bottom of the nest as it goes onward in search of a fresh victim. By the time the door of the cell is reached, the chrysalitic state is passed, and the young fly emerges to do battle on its own account. I have generally found that when several nests are built together by our fly, out of eight or nine eggs only two or, three reach maturity. This, I think, is owing to those flies that are first hatched poaching upon the preserves of their younger brothers and sisters, thus depriving them of the nourishment necessary for their support. The red fly spoken of above has been known in this district for many years, but all residents agree in placing the time of the mason fly's arrival at .two years ago. This, to irie, is a complete puzzle. It does not appear to be known' elsewhere. Whence then its origin.?. Has Noah's selection" of stock for the Aik proved inadequate, and does the [Great Creator still continues his labours as time'develops wants hitherto unf elt or unknown. Is this the grand solution of the rabbit question? I do not write irreverently, but if the mason fly is not an importation but a recent creation, why should it be appointed to prey upon that interesting and harmless insect the garden spider,? During my childhood in DuneduTl spent hours 'studying ths" marvellous ingenuity of this member of the spider family, and would willingly have exchanged Mr G. M. Thomson's botanical lesson for any more interesting subject in natural history. There may still be many points connected with the mason fly that have escaped my notice, but Sunday is the only day I have leisure to continue my studies, as my occupation debars me from close attention to such a subject during the week. The specimens I have forwarded are — one live adult fly enclosed nninjured in a bottle and one dead fly. Box No. 1 contains 20 or 30 spiders and four or five grubs taken from the nest of one fly ; also one nest (with contents) built in a piece of bark. Box No. 2 contains three spiders, each with new-laid egg attached to body. Box No. 3 (packed with sawdust) contains pieces of nest showing clay kneaded by fly, also unfruitful eggs or chrysales containing dead fly. I do not know how the live fly will stand the journey, but if defunct when it reaches you, there will still be sufficient left for a naturalist to determine the species to which it belongs. I have placed two spiders in bottle with it to serve as food. One or two of the grubs in box No. 2 ought to have hatched out into fly by the time it reaches you, as they are in an advanced state, and the period of incubation is, I should think, about a fortnight. If the subject is of sufficient interest to your readers, I may at some future time describe any new features that may come under my notice. Fossickek. [We have forwarded the specimens to the Museum, and Professor Parker writes :— " As stated by " Fossicker," the insect is a wasp, not a fly. The habit of many of the Hymenoptera (bee and wasp group) of paralysing living insects to serve as a store of food for the lame is well known, and is described in the works of Darwin, Packard, and others. The habits of the New Zealand species do not appear to have been described, and any further' observation would be lof interest, especially if accompanied by

well-preserved specimens. Lavse, spiders, &c, should be sent in methylated spirit. Uninjured nests should also be sent."]