HYMENOPTERA 965 



about but remain quiet clinging to the roof of a chamber of the nest. 

 When the season for obtaining honey-dew is passed, these Hving cells 

 disgorge their supply through their mouths, for the use of the colony. 

 There are several species and subspecies of Myrmecocysttts in some 

 of which the replete form has not been found. 



Family BETHYLID^ 

 The Bethylids 



This is a large family of parasitic wasps, including many genera 

 and species. The family is widely distributed, representatives of it 

 being found in all parts of the world. Our species are of small or 

 moderate size. Those whose habits are known prey upon either 

 coleopterous or lepidopterous larvae, and before pupating most of 

 them spin cocoons. 



In this family there are eight exposed segments in the abdomen, 

 the petiolar segment is ver^^ short and scarcely perceptible, and the 

 ovipositor is a true sting. The majority of genera comprise species 

 that are winged in both sexes; but in a few genera the males alone 

 are winged. Some of the wingless females are ant -like in appearance. 



Among those species that prey upon important insect pests are 

 Neoscleroderma tarsalis, which is parasitic on the beetle, Silvdnus 

 surinamensis, and an undescribed species of Goniozus, which is 

 parasitic on the codlin-moth in Kansas. A detailed account of the 

 life-history of LcbUhs trogodermatis, which is an external parasite of 

 dermestid larvae, is given by Howard ('oi). This family was mono- 

 graphed by Kieffer ('14). 



The family RHOPALOSOMID^ although widely distributed is 

 a very small family. It is represented in our fauna by Rhopalosoma 

 poeyi, the larva of which was found by Hood ('13) to be an external 

 parasite of a bush-cricket, Orochans saltdtor, in Maryland. The 

 adult is nocturnal; it has very large eyes and ocelli, and the petiole 

 of the abdomen is long and slender. 



Family VESPID^ 



The Typical Wasps or Diploptera 



The family Vespida^ includes our most familiar wasps, the hornets, 

 and the yellow -jackets, and their near allies. All members of this 

 family are winged and nearly all of them when at rest fold their wings 

 lengthwise like a fan ; for this reason they are often termed the Diplop- 

 tera or the diplopterous wasps. In the habit of folding their wings 

 when at rest, the typical wasps differ from all other Hymenoptera 

 except the Gasteruptiidae, the chalcid genus Leucospis and the 

 genus Galesus of the family Belytidae. In this family the lateral ex- 

 tensions of the pronotum are angular extensions behind and above the 



