136 



THE AMERICAN ENTOMOLOGIST. 



or otherwise destroyed by the intruder, liut 

 this is a very different thing — as will be seen at 

 oiioe — from making use of au old second-hand 

 abandoned and unprovisioned nest, constructed 

 years ago bj- some other insect, and provision- 

 ing it afresh. Our American Cowbird always 

 deposits its eggs in the recent nests of other 

 birds, leaving its future offspring to be cared for 

 by another. But it would be a very different 

 thing, if it merely took the old abandoned last 

 year's nests of those birds, and provided its own 

 self for its own family therein. 



But, although we do not believe that any of 

 the genera of Digger Wasjjs ( Trypoxylon, Pelo- 

 poeus, Ayenid, and Sapyga), hitherto inferred 

 by certain authors to liave the habits of Guest- 

 wasps, do really have those habits, yet there is 

 one remarkable genus {Ceropalex) , belonging 

 to the Spider-wasp {Pompihts) family among 

 the Digger "Wasps, which most certainly has. 

 Hitherto nothing whatever has been positively 

 known as to the habits of this genus, although 

 St. Fargeau long ago asserted with regard to it, 

 that he had often observed females enter back- 

 wards into nests constructed by true Digger 

 Wasps, whence he inferred that it had the habits 

 of a Guest-wasp.* But St. Fargeau is so flighty 

 and fanciful an author, and he has told so many 

 similar tales about other Digger Wasps, f which 

 we now know to be not Guest-wasps, but to 

 build nests of their own, that his evidence would 

 not amount to much, if there were any reliable 

 facts to controvert his opinion. And indeed, 

 even if the facts that he fancied that he witness- 

 ed were just as he represented them to have 

 been, they scarcely justify^his inference. Luck- 

 ily, however, for the scientific reputation of the 

 French entomologist, we have a fact to bring 

 forward whicli demonstrates that — in this in- 

 stance, at all events — he was a good guesser. 

 The fact is this : We have already mentioned 

 having bred four specimens of a little Mud- 

 dauber {AgcTiia bombycina, Cresson), sketched 

 in Figure 106, b, from clay cells obtained in South 

 Illinois. Of these clay-eells we obtained inNov- 

 ember, 1867, tive specimens, all alike, and all of 

 them found in company under the bark of the 

 same tree, near South Pass in South Illinois. 

 From these five cells there hatched out, about 

 the end of .June, 1868, the four little Mud-daubers 

 just now referred to, and a single male specimen 

 of a beautiful and hitherto undescribed species 

 of the remarkable genus of Spider-wasps (C'ero- 



•St.Fargt'an.Bi.W. Meth. X, n, 183, (luoteilby Wi'sUvooil, 

 j7ilrocl. etc , H , p."2a9. 



t For example, aliout the penns Age7ua, or as he names ii, 

 Anoplius, Ilymenopt. III., \i\). HI-'J; ahniit the genus T ij- 

 poxyton^ ibid p. 22.'); etc. 



pales), already asserted by us to have the habit^ 

 of a Guest-wasp. The inference is unavoidable 

 — more especially as we had previously bred 

 very numerous specimens of the same little 

 Mud-dauber from the same kind of mud-cells 

 obtained in North Illinois — that this gaily 

 dressed Spider wasp (Cerojiales) had, some time 

 in the summer of 1867, laid an egg in one of the 

 five mud-cells found in South Illinois, and thus 

 appropriated to the uve of its future larva the sup- 

 ply of food laid up by the providentcare of the un- 

 fortunate, dingy-looking little Mud-dauber forits 

 own offspring. Otherwise it is impossible to ac- 

 count for two distinct kinds of Wasp hatching out 

 from the same lot of mud-cells. Several years be- 

 fore this, we had captured at large, in North Illi- 

 nois three females of this very same Spider Wasp, 

 which are if possible still more beautiful than 

 the male. From one of these the annexed highly 

 magnified sketch (Fig. 108), has been drawn, 

 in {(reference to drawing from the male; for the 



[FiK. 1('8.] 



.-■^ 



Colors-Jtlack, red auU yellow. 



females of the Digger Wasps, as stated before, 

 always have their legs more bristly and spinous 

 than the males of the same species, and it is 

 desirable that f lie reader should see with his own 

 eyes the armature of these important organs, in 

 the sex where it is most highly developed. This 

 genus, we may add, is especially remarkable 

 — as may be seen in the engraving — for having 

 hind legs of the most extravagant and dispropor- 

 tionate length. Ill the Appendix will be found 

 a full description of our new species — which 

 we have named the Iled-bellied Spider Wasp 

 ( Ceropalvs nijirentris)--a.nd a few other scientific 

 details in regard to this interesting group, the 

 true habits of which may now be considered as 

 for the first time definitively settled. 



Some authors have supposed that certain spe- 

 cies of Digger Wasps open their nests from time 

 to time, to furnish their young larv;f with fresh 

 supplies of the appropriate food. But both St. 

 Fargeau and Westwood discredit such state- 



