130 



THE AMEEICAN ENTOMOLOGIST. 



colored genus to which both insects belong 

 (Stizus), but three species have hitherto been 

 discovered in North America. "We give in the 

 Apiaendix a description of a fourth species of 

 tliis same genus, the " Short-winged Digger 

 Wasp" {Stizus brevipennis, u. sp.), of which 

 but a single specimen exists in the cabinet of 

 the Senior Editor, and none at all, so far as is 

 known, in any other collection of insects. 



The holes or nests dug in the earth by Digger 

 Was^js are, for the most part — especially in 

 loose, sandy soils— dug in the same manner as 

 Mr. Smith's Blue Wasp effaced all traces of its 

 nest, namely, by scratching with their front 

 legs, and scrabbling tlie loose dirt backward 

 with their four hind legs, the motions being 

 performed with the rapidity of lightning But, 

 as we saw above in the case of Dr. Packard's 

 and Mr. Holcomb's wasps, certain species occa- 

 sionally use their jaws in digging, and more 

 especially, perhaps, when the soil is hard and 

 solid; but, as a rule, they dig with their front 

 legs, and not with their jaws, and scrabble the 

 loosened dirt backward Avith their liind legs. 

 Hence, we can see at once, why most species of 

 Digger Wasps, and more particularly the 

 females, which have the actual work to do, have 

 their legs garnished plentifull}' — as has been 

 already stated, and as will be seen at once in 

 the wasps that are figured above — with long, 

 stiff bristles, or slender thorns. On the 

 other hand, the True Wasps, which, when 

 they dig at all, dig with their powerful jaws, 

 and not with their legs, have perfectly smootli 

 legs, as may be seen from the species figured 

 below (Figures 110, 111, 112) . A European Dig- 

 ger Wasp, however, {Ammophila sabulosa) — 

 belonging to the same genus as our Painted- 

 wiug Digger Wasp, (Fig. 100), which as we saw, 

 digs with its jaws and not with its legs — 

 although it has very bristly legs, is recorded as 

 using the long, sickle-shaped jaws, which are 

 characteristic of the genus, both in burrowing 

 and in carrying the sand out of its burrow; 

 thus approximating the habits of the Digger 

 Wasps to those of the True Wasps.* So true 

 is it, that in Entomology there is scarcely a 

 single general rule without its exception, and 

 that, wherever we open the great Book of 

 Nature, and whether we study the structure of 

 insects, or their habits, we find almost every- 

 where intermediate grades, and connecting- 

 links. 



The comparatively few Digger Wasps that 

 make their nests in timber, also have legs more 

 or less densely armed with the usual bristles and 



thorns, because it is necessary for them to be 

 able to scrabble the minute fragments of wood 

 out of the holes, which they gnaw in the sub- 

 stance of the wood to serve as nests for their 

 larvfe. In a single stick of partially decayed 

 firewood, we once found in the winter several 

 dozen of the nests of a small species of Wood 

 Wasp (Cmbro), from which in the ensuing sum- 

 mer wo bred about a dozen of the perfect 

 wasps. 



And now wc approach a great mysterj'. The 

 genus of Digger Wasps known as Pelopmus 

 (in English "mud-maker"'), to which appertains 

 the common Mud-dauber {Pelopceus lunatus, 

 Fabr.) shown in Figure 104, and well known to 

 make the so-called " mud-dabs" so often found in 

 out buildings, does not dig atall eitherin earthor 

 in wood.* On the contrary, it constructs its 

 nests of tempered clay, affixing them to the in- 

 terior of any buildings to which it has fi-ee 

 access, or to overhanging clifl's. In search of 

 moist clay for this i)urpose, it may often be seen, 

 during a long dr>" spell of summer weather, 

 perched on the ground 

 in the neighborhood of 

 wells and other places 

 where water is habit- 

 ually slopped upon 

 clayey ground. We 

 ^ should naturally ex- 

 pect, therefore, that, 

 as it has the same hab- 

 its as many of the 



Colors-Kl.ick .and dull yellow. True Wasps, it AVOllld 



have the smooth legs of a True Wasp and not 

 those of a Digger Wasp. No such thing. The 

 legs of the female Mud-dauber are obviouslj' 

 bristly, though not so stronglv as in the two 

 most nearly allied genera {Spliex and Ammoph- 

 ila), both of which are known to burrow iu the 

 earth. But Avhy should they be so, Avhen the 

 bristles are of no manner of use to her, an}' 

 more than the>' Avould be to a True Wasp? One 

 school of philosophers will reply, that its legs 

 are bristly, because ages and ages ago, in the 

 dim far-away vista of bygone geological years, 

 the genus took its gradual origin from some 

 species that did really dig holes in the ground, 

 and had bristly legs to enable it to do so ; and 

 that, in consequence of the disuse of its bristles 

 for generation after genei-ation through myriads 

 of geological ages, the bristles themselves have 



♦Sec Westwood, Trans. Enlom. Soc. London,!, ji, 200. 



a Blue Mud-diUiber (Ptf/o/ja*('uS ca'rulctis, hinn.). 



ci-Ttiiin Norllu'vn states but veiT rave in >iOi-tll 

 Illinois wliieh stroimiv resenililes at lirst sight the nine Dig- 

 ger Wasp llgiirecl above, (Fig. :I7) . If may be readily distin- 

 gnishcd, liowever from the latter, hy the different veining o( 

 Its IVont \ving3 and by its smooth legs . Kespecting the intei'- 

 miuable couinsion among our different ^^ A, Blue Wasps, 

 see the Appendix. 



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