CLASSIFICATION OF ANIMAL AGGREGATIONS 19 



birth to young parthenogenetically. This gynopaedium, consisting 

 of one female and her immediate offspring, may be designated a 

 monogyno paedium. The young also reproduce parthenogenetically, 

 and such a complex group may be called a polygyno paedium. These 

 colonies are homomorphic; but as winged forms appear, heteromor- 

 phic colonies are formed. In the autumn sexual generations appear 

 and produce a resistant over-wintering egg, which carries the colony 

 over the winter season. In this aggregation there are no benefits im- 

 mediately apparent. The brood is not cared for by the older mem- 

 bers or by each other. The individuals composing a crowd of aphids 

 are more easily cared for by ants of the myrmecocolous species when 

 together, but also are more easily preyed upon by their numerous 

 enemies. The massed aphids also tend to destroy the food plant on 

 which they cluster, to their own disadvantage. Deegener recognizes 

 no social advantage, and therefore regards the aggregation as ac- 

 cidental. 



c) Patrogynopaedia occur when both parents remain with their 

 offspring in groups. Those with no social benefits for their members 

 belong here, but this type of aggregation often carries with it some 

 social advantage, and so usually belongs in a later category. Necroph- 

 orus beetles live with their young in decaying animal bodies. This 

 association may confer social benefits under certain conditions, but 

 they are not recognizable in all cases. In these scavenger beetles, the 

 presence of a dead body seems to release a digging reaction whether 

 the individual is solitary or in company with others. Each individual 

 digs without reference to the others. The results may have no sig- 

 nificance for the assisting beetles, but only for the pair leaving their 

 eggs with the dead body. Obviously the whole has racial significance, 

 although without significance for many of the participating in- 

 dividuals. 



Combination family groups also occur in which the individuals 

 composing the aggregation come from more than one stem-mother. 



d) Synchoropaedia are formed when eggs laid by different females 

 in a favorable place hatch out and the larvae remain together from 

 the very first, not as separate families, but freely mixed into a com- 



