ORDER HYMENOPTERA 305 



The egg parasites (Prodotnqndoe) are extremely small, most 

 of the species being parasitic in the eggs of insects. Eggs of 

 web worms are parasitized and the whole development of 

 the Proctotrujnd is contained within the egg. One species 

 is described as one-nintieth of an inch in length, another one 

 one-hundred-and-fiftieth of an inch and the body very slender. 

 These serve a most important function in the destruction of 

 other insects, those that would otherwise hatch from the 

 eggs. When the parasites feed on the caterpillars the damage 

 is only partly checked, but when the parasite feeds on the 

 eggs the damage is all prevented. One of the important lines 

 of economic entomology is to study such forms and their 

 life histories with regard to other species, as primary para- 

 sites, secondary parasites, tertiary parasites, etc., since 

 their value depends on whether they directly control a pest 

 or whether as a secondary parasite they reduce the niunbers 

 of a primary parasite which is useful. 



Ants (Formicina) are one of the most interesting groups 

 of insects. They are sometimes given the rank of a superior 

 family, but the principal family is that called Formicidce. 

 The name is associated with the secretion of formic acid. 

 The name of the group probably gave the name to the 

 chemical. The secretion is one of the characteristics of the 

 Hymenoptera. Ants present striking habits of family life; 

 the formation of different classes among the individuals 

 of a colony. This separation into classes is paralleled in 

 other groups, as the bee family and among wasps, and 

 expecially the termites. The result of community life is 

 that it presents certain relations in the community in the 

 way of division of labor. The primary forms are males 

 and females, and then a class which are not sexual but are 

 derived from a modification or suppression of the reproduc- 

 tive factor in one of the sexes. Occurring with this is the 

 reduction or complete absence of wings. These constitute 

 the so-called workers or soldiers of a colony. They have no 

 wings whatever. This feature reaches far back into the 

 ancestry of the group, or else shows parallel evolution. 

 Sexual individuals have wings primarily but in the case of 

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