Makch 1, 1886.] 



♦ KNOV/LEDGE ♦ 



153 



of a coarser texture, and incliues to a yellowish brown, 

 instead of the delicate grey of the smaller species. As 

 an instance of the rapidity with which these insects 

 work, the following particulars, given by Mr. B. S. 

 Standen, concerning a hornet's nest found, in the summer 

 of 1881, in a shed in Norfolk, may be quoted. It was 

 constructed in a thin shell of mortar about the size of a 

 lemon, and open at one end. It was commenced on 

 June i4, and the wi-iter goes on to say: — "Although 

 when I first observed her (the queen hornet), the shell 

 was perfectly empty, by the morning of the 128th — less 

 than five days — she had constructed twenty-six cells ; 

 two were empty, seventeen contained eggs, five had good- 

 sized larva\ and the remaining two were ali'eady sealed 

 up for the pupa stage.'' Prudential considerations at this 

 moment suggested the advisability of putting a stop to 

 the further development of this interestiug colotiy, lest 

 battle might have to be done against scores of winged 

 warriors, in.stead of one solitary heroine ; and the whole 

 colony, together with its foundress, were accordingly 

 massacred. Many other instances are on record of the 

 occurrence of hornets' nests in sheds, lofts, and thatched 

 roofs. 



The Si rex mentioned above may now come in for a 

 somewhat more detailed notice. It occasionally occurs 

 in houses in the same way as the large longicorn beetles 

 referred to in a previous paper ; it is a wood-borer, and 

 attacks fir-wood chiefly, and its larvte and pupas are 

 therefore sometimes present in the timber used in the 

 construction of houses ; and, enclosed in this, the imma- 

 ture insect maj- be introduced into the edifice, the com- 

 pletion of its metamorphosis being delayed till after the 

 timber has been placed in position, when it emerges, to 

 find itself, not amidst its native pine.^, but an uninvited 

 guest in. society to which, on account of its size, its 

 appearance, and its loud buzzing, it is often an object of 

 unnecessary terror. Sometimes it does not issue from 

 the wood for a con.siderable time, which may occasionally 

 amount to years ; amongst other instances, there is a 

 record of the emergence of several specimens from the 

 floor of a nursery in a house that had been built for three 

 yejrs, and where, very naturally, they caused quite a 

 fright to the children who were its occupants. Usually 

 they occur in houses either sing!}', or at most in twos or 

 threes, but sometimes considerable numbers have been 

 met with ; for instance, in the summer of 1878, no less 

 than a dozen specimens were captured in an ironmonger's 

 shop in Chichester. It is obvious that in man)- cases 

 these household specimens may not really be British at 

 all, but, if the timber be foreign, may have been imported 

 with it. 



The female of Sirex ijigas (Fig. 2) has a black head and 

 thorax, and a long cylindrical yellow abdomen, with a 

 liroad black band, like a mourning band, across the 

 middle. Behind the eyes, which are not situated on the 

 bend of the head, as they are in wasps, are also two 

 yellow patches, which are so conspicuous and shining, 

 that they might very probibly at first sight be mistaken 

 for the eyes themselves. Tlie antennfe and legs are long 

 and yellow, and the f.irmer are proportionately much 

 longer than in the wasps, since they consist usually of 

 about twice as man j- joints. The four large membrandus 

 wings are shining and transparent, though strongly 

 tinged with yellow, and are withotit the minute hairs 

 that cover those of wasps. When the wings are fully 

 spread, the insect may measure as much as two inches 

 across, but specimens are often found much smaller 

 than this ; like all wood-feeding insects, they vary 

 gi-eatly in size. The abdomen is attached to the thorax 



by the whole of its base, instead of the slender peduncle 

 that constitutes the familiar and proverbial wasps waist. 



But the most interesting part of the insect is the 

 ovipositor, which consists of three parts, two yellow side- 

 sheaths, which are toothed outwardly towards the extre- 

 mity, and a black central borer, which is notched at the 

 end, and is therefore able to act something like a gimlet. 

 This instrument runs up underneath the abdomen, and 

 has its origin more than half way up the latter ; it also 

 projects beyond the abdomen to about the same extent, 

 and measures almost an inch in total length. In addition 

 to this, the last segment of the abdomen is produced 

 above into a long and stout spine, which is nearly half as 

 long as the free part of the ovipositor. "With the ovi- 

 positor the mother pierces the bark of the tree she has 

 chosen for the stipport of her progeny, in order that she 

 may deposit her eggs in such positions as shall place the 

 young grubs in circumstances of comfort and opulence 

 from the moment they first see the light. 



Her consort is altogether a slenderer, smaller insect, 

 and has a reddish body, without the mourning band — and, 

 of course, without the formidable boring apparatus ; all 

 he can show in the way of offensive or defensive weapons 

 is a very sharp point at the end of the last segment of 

 his abdomen, in the same position as the much larger 

 sjiine of his spouse. 



Fig. 2. — Sirex gigas (female), natural size. 



Sirez gigas is sufficiently large to show with tolerable 

 ease a certain structure in the wings which is eminently 

 characteristic of the Hymenoptera, though often too 

 small to be readily seen. When spread out, the fore and 

 hind wing on each side will be found to be in .some 

 mysterious way connected, so as to move in concert, and 

 to offer, over the greater part of their area, one unbroken 

 resisting surface to the air. If, however, they are waved 

 about in various directions, they may at length be caused 

 to spring apart, and then, if the front edge of the hind 

 wing be held towards the light, the explanation of the 

 mysterious union will be found. Here will be seen, 

 running ]>art of the way along the margin, a row of 

 between fifty and sixty tiny hooks, bent upwards and 

 backwards in sach a way that when the wing is brought 

 into position behind its fellow, they clasj) from under- 

 neath th^ stout nervure which bounds the forewiug on 

 its hinder edge, and thus hook the two wings together. 

 In the centre they are placed much more thickly than at 

 the ends, and show a tendency to form two distinct rows. 

 It is obvious that this arrangement greatly increases the 

 power of the wings, and no doubt largely contributes 

 towards that vigour of flight which is so prominent a 

 feature in the Hymenoptera. 



The larv» are fat, whitish maggots, with six very tiny 



