170 ENTOMOLOGY. 



Family Chrysididae. — In the species of this interesting group, there 



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Fig. 216.— Pelecinus, male and female. 



Natural size. 



Fig. 217.— Chrysis hilaris. 



are only from three to five complete abdominal segments, the 



remainder forming a telescopic, retractile 

 tube, containing a sting-like ovipositor. 



The Chrysis flies are blue, green, and 

 ruby-red, with rich metallic reflections. 

 The females, cuckoo-like, lay their eggs 

 in the already provisioned nests usually 

 of solitary wasps and bees, the larvae eat- 

 ing the food stored up, causing starvation 

 and death to the young of their hosts. 

 Typical genera are Cleptes, Elampus, 

 Hedychrum, Chrysis and Paruopes. 



The ants, formerly all included in the old family Formi- 



cidse, are now regarded as forming a section or super-family 



Heterogyna, which is characterized by the petiole of the 



abdomen having one or more scales or nodes; while the 



antennae are elbowed. Ants live in societies consisting, 



besides males and females, of workers. There are five 



families, characterized as follows: 



Family Formicidse. — In this (and the three following families) the 

 petiole has but a single joint; the abdomen proper (not including 

 the petiole) is not constricted between the first and second segments", 

 while the mandibles are inserted wide apart. The elypeus is always 

 distinct and often very large; the frontal crest is more or less long, 

 not surrounding the insertion of the antennae, and the petiole is 

 almost always surmounted by an erect scale. Most of our ants be- 

 long to this group; their larva' usually spin a thin but tough cocoon. 

 Ants are fossorial, digging mines and galleries underground, or 

 excavating them in old stumps and trees. A complicated society or 

 nest of ants is called a " formicarium;" the work of which is carried 

 on by the wingless individuals, called workers. 



Certain ants enslave other species; have herds of cattle, the 

 aphides; tunnel broad rivers, lay up seeds for use in the winter- 

 time, are patterns of industry, and exhibit a readiness in overcoming 

 extraordinary emergencies which shows that they have sufficient 



