CLASSIFICATION OF THE SPECIES. 27 
and pointed, crossing each other when at rest, and 
armed, as the microscope shews us, with five teeth. 
The tongue is longer and more deeply cleft than in 
the Vespee. The arrangement of the nervures of the 
wings is very lke what there will be occasion to 
trace further on as displayed in the social group. 
The technical character by which social and solitary 
wasps are most readily distinguished is found in the 
tarsal hooks, which are simple in the social and 
denticulated in the solitary group, and, by the aid of 
the microscope determining this point, the Odyneri 
may at once be referred to their proper place as 
solitary: wasps. 
In a social and physiological pomt of view the 
differences between these groups are very obvious. 
Still taking the Odyneri as the most familiar type of 
solitary wasps, we find among them only perfect 
‘females and males, the latter much smaller than their 
partners. There are no imperfect females. Both 
sexes appear at the same time, early in the summer, 
and shortly set about the work of their lives. The 
mother-wasp makes cells of sand, or any other ma- 
terial, agglutinated with mucus. She deposits any~ 
egg in each cell, and with it a store of small cater- 
pillars as food for the larva against the time when it 
shall be hatched. These caterpillars she stings, not 
so as to kill them outright, for in that case they 
would dry up or putrefy, but just enough to paralyze 
them. As some exotic species seal up small insects 
and spiders in this way it is necessary to keep them 
quiet, otherwise the tables might be turned on the 
larva, and it might be eaten up itself instead. 
When the mother-wasp has built and provisioned 
