132 



THE AMERICAN ENTOMOLOGIST. 



iie female of the wasp {Agenia hombijcina, 

 ifssoii). Figure lOfi, 6, that constructs it. From 



[Fig. lOG.] 



( ciliirs— (a) clay-yellow; (b) dingy black , 



these four diflferent kinds of mud-cells, we have 

 bred specimens of the four different species of 

 Spider "Wasp (Ar/enia) that build them, three of 

 which are described species, and oue (Ag. siib- 

 corticalix), a new and hitherto undescribcd 

 species. This last is considerably the smallest 

 of the four, and its nest, which we have always 

 found exclusively under the loose bark of 

 standing trees, is shown in Figure 105, c. The 

 next largest species is one which was described 

 thirty-two years ago by Thos. Say (Agenia 

 Ipompiliis] architect Hs)\ and it is very remark- 

 able that, although he gives a very elaborate 

 description of the mud-cells from which he bred 

 it, he says not a single word about the smooth- 

 ness of its legs, and refers it to the same genus 

 (Pompiliis), to which belong the closely allied 

 species with strongly-armed legs. We may 

 add that Say found the mud-cells, from which 

 he bred his specimens of this insect, " under 

 prostrate logs and stones," while we found 

 our two mud-cells under the loose bark of 

 standing trees. The largest species but one 

 (Ag. meUipex), was described by Say at the 

 same time as the other one, merely from cap- 

 tured specimens, and without any knowledge 

 of its habits, or any notice of its legs being 

 smooth. This species we have also bred from 

 mud-cells found exclusively under the bark of 

 standing trees. Finally, the largest species of 

 the four {Ag. bombycina), Figure 106, 6, was de- 

 scribed only two years ago by Mr. Cresson, 

 without any knowledge whatever of its habits. 

 This last we have bred iu large numbers 

 from mud-cells found under prostrate logs in 

 North Illinois, and four specimens from similar 

 mud-cells found under the bark of a standing 

 tree in South Illinois. Unlike the other three, 

 il has very small rudimental spines — scarcely 

 perceptible except under the lens— on its legs. 

 In the Appendix will be found a full descrip- 

 tion of the new species of smooth-legged Dig- 

 ger Wasps referred to above, and a few other 



dc'ails relative to this singular genus {Agenia), 

 which would not interest the general reader. 



It may be objected perhaps by the entomologi- 

 cal purist that, as all these builders of mu-dcells, 

 including the common Mud-dauber (Fig. 104) 

 never dig at all, either in the ground or in de- 

 cayed timber, or anj^ where else, it is incorrect 

 to call them " Digger AVasps." But a general 

 name must not be changed because it is inap- 

 plicable to particular species. Many Bark-lice, 

 for example, do not inhabit the bark but the 

 leaves of plants ; for instance the Scale-insect 

 of the Oleander {Asjiidiottis nen'i, Bouche). 

 Yet this last is none the less a true Bark-louse 

 {Coccus family). Again, we have seen with 

 our own eyes the common Bed-bug {Acanthia 

 lectularin, Linn) actually swanning, not in beds 

 frequented by Christians, but in a chicken- 

 house. Yet any precisian Avho should insist 

 that, when it infested a cliicken-house, it ceased 

 to be a "bed-bug"' and became a "chicken- 

 bug," would be simply ridiculous. Upon the 

 same principle, a smooth-legged Spider Wasp 

 does not cease to be a true Digger Wasp, because 

 it never digs. 



Not being aware of the habits of these small 

 smooth-legged Digger Wasps, any more than 

 anybody else, and being misled by certain mis- 

 statements as to the origin of our common 

 American "mud-dabs," Westwood has advanced 

 the erroneous opinion, that "it is only among the 

 Bees and (True) Wasps that we find the habit 

 of constructing nests with materials brought 

 from a distance."* This habit, it is true, is the 

 exception and not the rule among the Digger 

 Wasps. AYe find it more common among such 

 of the True Wasps as are solitary in their hab- 

 its. But when we come to the most intelligent 

 and highly-developed of the whole group — 

 namely, such of the True Wasps as arc social 

 and live in largo communities — we find it uni- 

 versal. Undoubtedly this practice displays 

 great intelligence, and is as wonderful as the 

 proceedings of most birds in building their 

 nests with materials fetched from a distance. 

 It is interesting, therefore, to observe here and 

 there the first developments of this curious in- 

 stinct among the lower Wasps — its gradually 

 becoming moi-e common among such Wasps as 

 approximate in their organization to the Social 

 WaspS — and its full and complete culmination 

 among the latter, which are universally con- 

 sidered as the highest and most intelligent of all 

 the Wasps. 



The mud-daubing Spider Wasps {Agenia) are 

 not exempt from the attacks of p.arnsites any 



•Intn.diu-linii, II I) 2UT, 



