THE AMERICAN ENTOMOLOGIST. 



135 



vre found a single large cell divided by a i)arti- 

 titioii into two small cells, each of which con- 

 tained what was evidently the cocoon, not of a 

 Digger Wasp but of a True Wasp. Now, the 

 larva of this wasp had manifestly been provi- 

 sioned with caterpillars and not with sjiiders ; for 

 each cell contained eight or ten of the empty skins 

 of some moth-larva or other upon which the 

 wasp-larva had fed. Consequently, as the Mud- 

 dauber provisions its nest, not with caterpillars 

 but with spiders, the wasp that provisioned these 

 two cells must evidently have catered for its own 

 offspring. It was probably from some such case 

 as this that Palisot de Beauvois, as quoted by 

 Westwood. was deceived into stating that the 

 Mud-dauber sometimes provisions its nest with 

 spiders, sometimes with caterpillars.* We have 

 opened liundreds and hundreds of their nests, 

 and we are sure that they invariably use spiders 

 for this purpose. 



It may be added that, in all probability, the 

 two larv» of Tiuc Wasps, just now stated to 

 have been discovered by us in Mud-dauber cells, 

 would have developed into the Fraternal Wasp 

 {Eumenes J'ratcrna, Say) which will be found 

 tignred below (Fig. 1 10, «) ; forwehadlongbefore 

 this period bred from common '•mud-dabs" 

 three males of this very same species. We can- 

 not, however, speak positively' as to this ques- 

 tion ; for we had to strip the cocoon off one of 

 these two larvae in order to examine it, after 

 which it of course perished; and from the other 

 larva there subsequently hatched out on May 

 19tb, not the wasp itself, but a pretty blue para- 

 sitic fly (Chri/sis he/In. Cresson) common in 

 North Illinois, which had preyed upon the larva 

 of the Wasp. Not improbably, it was from same 

 such occurrence as the above, that Mr. Saunders 

 led ProfessorAVestwood into the erroneous belief, 

 that '• mud-dabs " were really made by the same 

 genus of True Wasps (Eitiiiciies) to which the 

 Fraternal Wasp actually bred by us from " mud- 

 dabs " appertains : and that the veritable Mud- 

 daubers (Pelopieus) were merely parasites, or 

 rather Guest-Wasps, sponging upon True Wasps 

 for food and lodging. f 



In illustration of the curious propensity of the 

 Black Wasp (Fig. 107), spoken of above, to habit- 

 ually build and provision its nest in the old de- 

 serted nests of the Mud-daubei-, we may quote 

 here a very similar case observed in South 

 America with regard to another species of the 

 very same genns {Triipoxijlon). For calling 

 our attention to this case we arc iiulebted to the 

 kindness of Baron Osten Sacken, of New York 



«,p/i'., II, 11. iOli. 

 «, etc., II , |i, 217. 



city: "Mr. Clark found in Brazil, that Trypox- 

 ylon fugax closed with clay the cells of a nest 

 of PoUsles, thus using them for its progeny." * 

 PoUstes, we may add here, is a genus of social 

 Tnie Wasps, which will be found figured below 

 along with its nest. (Fig. 112, «). Accord- 

 ing to Linn»us, whose assertions were subse- 

 (luently confirmed by the researches of West- 

 wood, the common practice in Europe of this ge- 

 nus of Digger Wasps (Tri/poxi/lon) — the name 

 of which is most unfortunately derived from 

 two Greek words signifying " timber-borer" — 

 is, not to bore into timber at all, but to take 

 possession of holes in wood that have been pre- 

 viously made by other insects, and occasionally 

 hollow straws, and therein to construct its 

 nests, t 



Seeing, therefore, that it seems to be a well- 

 established fact, that the habits of this ge- 

 nus of Digger Wasps are, neither to burrow 

 in the ground nor in wood, but to seek out 

 ready-made holes or the old nests of other Dig- 

 ger Wasps for its nest, linishing them ofl' with a 

 little mud that it fetches there itself; we might 

 naturally expect to find its legs either perfectly 

 smooth or very nearly so. Now, what are the 

 facts? They are actually quite smooth, and this 

 character has been duly recorded by St. Fargeau, 

 who, however, draws the erroneous inference 

 therefrom that the genus has the habits of a 

 (.iuest-wasp.J 



On the whole, therefore, as we have shown 

 that at least two distinct genera of wasps 

 ( Trypoxylon, and Eumenes,) sometimes use the 

 old second-hand cells of the Mud-dauber to 

 build their own nests in, under circumstances 

 which would mislead most naturalists into sup- 

 posing that they were true Guest-wasps; and as 

 all the recorded cases of so-called Guest-wasps 

 that we have met with, arc explainable upon 

 similar suppositions, we incline to believe that 

 no author has yet made out a clear and satisfac- 

 tory case of the existence of such a thing as a 

 true Guest-wasp, though undoubtedly there are 

 many true Guest-bees, Guest-gallflies, Guest- 

 sawflies, Guest-beetles and Guest-gallgnats. A 

 true Guest-insect — or " Inquiline," as it is tech- 

 nically termed — deposits its egg in the recent 

 nest of another insect, and appropriates for the 

 use of the larva, that afterwards hatches out 

 from that egg, the supply of nourishment pro- 

 vided by the mother-insect that makes the nest; 

 the egg or the very young larva of this last 

 mother-insect being afterwards often starved out 



• From .a pajjir bv Mr. Smitli in Proe. London Enlom Soc 

 IV. p. 77, 1838. 

 t Westwood, Iplrodnction etc., II, pp.IC4-5. 

 J St. Fnv^eitu, Hymenoptats . Ill, p. -ia.'j. 



