660 THE STUDY OF INSECTS. 



keyholes in our house, including those in the bureaus ; thus 

 constructing for us locks that required a good deal of time 

 and industry on our part to open. Some species of Odyne- 

 rus are masons constructing nests entirely of mud. One of 

 our species makes a nest about the size of a hen's egg. This 

 is composed of hard clay, fastened to a twig of a bush, and 

 contains many cells. 



Probably the most skilful of architects among our soli- 

 tary wasps is Monobia quadridens (Mo-no'bi-a quad'ri-dens), 

 a species common in most of the states east of the Missis- 

 sippi (Fig. 787). This insect bores a tunnel in solid wood. 

 Figure 788 represents a nest in our collection which was 

 made in a board in the side of a barn. The partitions are 

 made of mud. Each cell contained a pupa when the nest 

 was opened ; so we do not know with what the nest was 

 provisioned. 



Family Vespid^E (Ves'pi-dae). 

 The Social Wasps. 



Here again, as with the ants, we find colonies consisting of 

 three forms of individuals, males, females, and workers. The 

 colonies exist for only one season ; the males and workers 

 die in the autumn ; the females hibernate and each starts a 

 new colony in the spring. In the early part of the season 

 only workers are produced ; later the males and females ap- 

 pear. The three forms are similar in coloring. They are all 

 winged, and the queens and workers are provided with ven- 

 omous stings. The queens are larger than the workers, and 

 the males have seven segments in the abdomen, while the 

 others have only six. The male wasps do not sting, but they 

 bear such a close resemblance to the belligerent, well-armed 

 workers that this interesting bit of knowledge is entirely 

 useless. When we see a hornet our interest in its sex hardly 

 leads us to test it to see whether it will sting, or to examine 

 it closely to ascertain if it has seven abdominal segments. 

 If male wasps wish to get any credit for their amiability, 



