392 Mr. F. Smith on Wasps and their Habits. 



most important discovery was observed by myself and pub- 

 lished sixteen years ago. Among the Pompilidse there is a 

 section that have the anterior tarsi simple (that is, without 

 cilia) and their intermediate and posterior tibiae without spines : 

 such is the character of the division named Agenia ; but when 

 we examine a large number of exotic species, we find that, 

 although we call them smooth -legged, some species have a few 

 bristles on their tibiae — though in such cases they are rudimen- 

 tary or extremely fine. These insects are mud-daubers, con- 

 structing cells after the same fashion as the Pelopcei. Mr. Walsh 

 finds their cells usually under the loose bark of trees. The 

 species whose history I published had constructed its cells on 

 the top of a bee-hive that was covered with an old cloth and 

 a pan ; from these I bred both sexes of Agenia punctum. 



Such is the habit of Agenia, a builder of mud cells, and we 

 are led by Mr. Walsh to infer that such is the habit of the 

 entire genus, his conclusions being, of course, drawn from the 

 fact of the species being destitute of armature on the legs ; such 

 generalizations, however, will be found to have exceptional 

 cases : I have observed one myself. 



In the north of England, Agenia variegata is not an un- 

 common species ; and in the summer of 1852 I observed se- 

 veral females burrowing in a bank of light earth : I also once 

 took a pair running on a bank at Coomb Wood, in Surrey ; 

 and I am inclined to believe this to be the constant habit of 

 that species. 



I have noticed the fact that some species of sand-wasps 

 have never been observed to burrow, but avail themselves of 

 some ready-formed burrow or hole suitable to their require- 

 ments ; as instances of this habit, I may refer to Trypoxylon 

 fugaxy a Brazilian species that was found to have used empty 

 cells in a nest of a species of wasp (Polistes). Trypoxylon 

 stores up spiders, as it had done in this instance, and after- 

 wards had closed up the cells with clay. 



Mr, Home has noticed a similar habit in an Indian species 

 of Trypoxylon, which took possession of clay cells constructed 

 by a species of the genus Pison ; this insect attaches its cells 

 to twigs and stems of grass, and, as is the habit of Trypoxylon, 

 stores up spiders. Here a question may arise as to whether 

 in this instance the Trypoxylon appropriated the store as 

 well as the cell of Pison ; if such were the case, we should 

 have the anomaly of an insect being at one time a provident 

 creature and at another time a parasite : certainly until such 

 a fact is clearly established, we cannot assume it to be the 

 case ; I know of no circumstance that would justify such a 

 conclusion. 



