PHYLUM ARTHROPODA — CLASS INSECTA 335 



ress. Despite this, Wheeler, the great authority on insect societies, 

 pointed out that at least twenty-four different times communism 

 or societies have appeared in the class Arthropoda. He reports that 

 social life occurs in six families of Coleoptera, fifteen families of 

 Hymenoptera, and in the Dermaptera, Embiidina, and Isoptera. 

 Let us look at some of the ways social life has manifested itself. 



In the beetle family, Scarabaeidae, we find a number of species in 

 which there is a cooperation between the male and female for the 

 perpetuation of their offspring. A common species, Canthon sim- 

 plex var. corvinus Harold, which the writer has ofttimes observed, 

 rolls up small spheres of fresh cow manure, and then excavates be- 

 neath the roll, letting it gradually down into a hole in the ground. 

 The male helps to dig and cover over the sphere of manure upon 

 which the female has deposited an egg. The French naturalist and 

 entomologist, J. H. Fabre, reported many interesting observations re- 

 lating to the preparation of manure pellets for the deposition of eggs 

 by several different scarabaeids. 



Another beetle, Passalus cornutus, in the family Passalidae, lives 

 in rotten logs. The developing larvae feed upon wood that has been 

 prepared by the adult beetles. The colony is kept together by audible 

 noises made by the mature beetles. 



The ambrosia beetles of the families Scolytidae and Platypodidae 

 form colonies by making their burrows into the wood of both living 

 and dead trees. Each species of beetle grows a species of fungus 

 which is fed to the developing larvae by the adult beetles. 



The beetles are probably the least social of all the orders listed. 

 No castes have been developed, and the males take but little part 

 in colony life. 



In the Hymenoptera are found varying stages of social life. In 

 the solitary wasps, the female digs a burrow in the ground which is 

 provisioned and then an egg is sealed in the cell. No other atten- 

 tion is given to the developing young and the new generation never 

 knows the old. 



The following excerpt from a study of the nesting habits of 

 Odynerus dorsalis Fabr. made by Mr. Edwin Vest gives a good pic- 

 ture of the activities of this solitary wasp. 



'' Odynerus dorsalis is a solitary wasp in that each female builds 

 a separate nest, yet there are often several nesting individuals in 

 the same vicinity forming a kind of community. The labor of dig- 



