Oct. 9, 1885.] 



♦ KNOAAALEDGE 



309 



from tlie crowds of other yellow-banded insects. All 

 wasps have four wings, and this will serve to distinguish 

 them from certain two-winged flies of the order Diptera, 

 with which they are sometimes confounded, but will not 

 distinguish them from other Hymenoptera, as four is the 

 natural number of wings in this group. But the anterior 

 wings are folded longitudinally in repose, i.e., when a 

 wasp closes its wings it not merely lays them along its 

 back, as a bee would do, but also folds each fore-wing 

 along a line running from its attachment to the thorax to 

 the middle of the outermost or rounded edge of the wing 

 (Fig. 1), the lower and more flexible part being bent 



under the rest, so that the wing becomes only half as 

 broad as before. 



In consequence of this peculiarity, the name Diplop- 

 tera, or " doubled- wings," is given to that section of the 

 order which contains all the wasps, and by this pecu- 

 liarity they may at once be distinguished from all other 

 Hymenoptera. One would naturally suppose that there 

 must be some connection between this curious habit and 

 the economy of the insects — something to account for so 

 strange a departure from the general practice of the 

 order ; but if there be, it has yet to be discovered. 



Our British wasps are of two totally distinct kinds. 

 Those that usually obtrude themselves upon our notice 

 are the social wasps, of the family Vespiclw, and, like the 

 ants and other social insects, they exhibit the peculiarities 

 of the three so-called sexes, the common abode, and the 

 common labour for the common welfare. But besides 

 these there are the solitary wasps, of the family Eumt tudir, 

 which, from their habits of burrowing ia sandy banks, 

 are often called Saud "Wasps and Mason Wasps. These 

 have but two sexes, do not form large communities, and, 

 after having provisioned their nest with food sufficient 

 to last the whole lifetime of the larva;, leave their young 

 to take care of themselves. They are less robiist than 

 the Vespidoe, and though still yellow-banded, have a 

 much larger proportion of black about their bodies. 



It is only very occasionally that we find solitary wasps 

 in our houses ; their young feed upon small caterpillars 

 and other insects, and the chief business of the parents' 

 life is to provide a stock of these, so that they have not 

 the temptation to intrude on our privacy which the 

 Vesindiv have, for the latter are almost omnivorous, and 

 there arc plenty of things in our houses which suit their 

 taste admirably. The solitary wasps of the genus 

 Odijnerus do, however, sometimes construct their small 

 nests in the most outlandish places. The nests consist 

 of separate cells, each closed in and complete in itself, 

 and devoted to the use of a .single grub. Each contains 

 an egg and a store of little caterpillars, each stung by 

 the mother wasp sufficiently to prevent it from being at 

 all lively, but not sufficiently to cause it to die and 

 •shrivel up. 



T1m-> litil.- .lu-iri's of cells have been f.m 

 otlu 1 1 !> . i5i IS, inside the lock of a k 

 will r- , 1 . , I ', I iiMling the noise and ilislm-l 

 by (til- p;i: Mil-- ;iihI r(>passing of persons cdiiti 

 in and out of the kitchen, the mother built ( 

 brood, provisioned them, and sealed them 



young went through all their motamoi 1 1 . f Jl\ , 



appearing in the' kitchen ^^h(n the} i i'. 



perfect form, to the no small surprise > I i 



In the keyhole of an eight-day cl < no 



family was brought up, appearing to be in no way dis- 

 turbed by the ticking or periodical winding-up of the 

 clock. They have also been found in the drawer of an 

 old-fashioned looking-glass, in the folds of a piece of 

 paper that had fallen behind some books, in hollow 

 reeds used as thatch, and in the barrels of a pistol that 

 was hanging invitingly on a post. In all these cases, 

 accident furnished the insects with cavities ready made, 

 and saved them the trouble of excavating their own 

 burrows. These wasps are also sometimes seen in win- 

 dows, buzzing about, apparently endeavouring to discover 

 why a medium so transparent as glass should yet be able 

 so successfully to bar their exit into the outer world. 



The abdomen of an Odyncr-us is of a very curious shape. 

 In all the wasps, the first segment seems more or less like 

 a cap on the succeeding ones, but this is much more 

 markedly the case in the solitary than in the social 

 species. In the genus Odynerus the abdomen bears a 

 ludicrous resemblance to a peg-top surmounted by a polo 

 cap which is rather too small for it (Fig. 2). The second 

 segment is of enormous size compa 

 with the succeeding ones, and being very 

 convex above, forms the head of the top. 

 This segment is black, except the hind 

 border, which is yellow, and the s 

 ceeding segments are more or less deeply [' 

 margined with the same colour. The ^ 

 basal segment, i.e., the cap, is also fur- 

 nished with a yellow marginal band, 

 the shape of which is an important aid in 

 the identification of the species. The 

 folded wings and the top-shaped abdomen Fig. 2. — Abdomen 

 are quite sufficient to enable any one to "f Odynerus. 

 recognise a sand -wasp. 



The Vespida; or social wasps, which are much more 

 frequently seen in our houses, we must reserve for the 

 nest paper. 



(To he continued.) 



THE YOUNG ELECTRICIAN. 



By W. Slixoo. 



(Cmiii7ived from p. 219). 



EX. CIX.— Before leaving tlic i,"' - > ' ' ' ■"- 

 scopes there are one or t«" j" n ' 



do to overlook. Nothing was sail in t' 

 about a base for the iustrununt (.U.-c:.:.. . -.- -- it 

 essential to have one, as it can he simply ^tu^d on the 

 table, or any other dry substance. IIowiviv, there 13 



onie danger of damaging the leaves when canning the 

 iistrument from place to place if there is nothing to ex- 

 lude currents of air. Fig. 64 gives a general idea of a 



