HYMENOPTERA PETIOLATA. 



761 



the second posterior by one cell only. This family is closely allied to the 

 preceding one, and is separated from it almost wholly by the presence of 

 the single cell on the fore-wing just mentioned. The parasitic habits of 

 the larvae are similar in the two families. The distribution of the two 

 families is alike. The Braconidae contains a very large number of species 

 many hundreds of which occur in this country. 



Fam. 10. Stephanidae. Many segments (thirty to seventy) in the 

 antennae ; head spherical ; wings with a costal cell ; posterior femora 

 usually toothed. An ill-defined family comprising two rare but widely- 

 distributed forms Stephanus and Stenophasmus. 



Fam. 11. Megalyridae. The abdomen is short and broad and the 

 waist is wanting ; female with a long ovipositor ; antennae fourteen- 

 segmented. This family includes only the rare, anomalous, Australian 

 Megalyra. 



Fam. 12. Evaniidae. The waist or second abdominal segment is 

 inserted on the dorsal aspect of the first or propodeum ; antennae 

 straight, with thirteen or fourteen segments ; larvae parasitic. Another 

 small family of three genera : Evania (whose larvae live in cockroach egg- 

 cases), Gasteruption and Aulacus (whose larvae devour other Hymenop- 

 terous insects). The genera have a large number of species a few of 

 which are British. 



Fam. 13. Pelecinidae. Trochanter not divided ; marked sexual 

 dimor phism; the 

 female has a very 

 long abdomen, but 

 no ovipositor. Again 

 &, family of three 

 genera, Ophionellus, 

 Monomachus and 

 Pelecinus, the last 

 named common in 

 the warmer parts of 

 America. The larvae 

 are said to be para- 

 sitic in other insects. 



Fam. 14. TrigO- 

 nalidae. The oval 

 abdomen of five 

 visible segments has FIG. 492. Chrysis ignita ? . England. From Sharp, 



no waist ; antennae 



twenty-five segmented ; trochanter partly divided ; wings with many 

 nervures. Another small family, whose chief genus Trigonalys is repre- 

 sented in Britain by one species. 



Series 2. TUBULIFERA. 



Trochanter not divided ; abdomen shows only three, four, or five segments ; 

 ovipositor transversely segmented and usually withdrawn into the body. 



Fam. 15. Chrysididae. Bright, metallic insects with hard exoskeleton ; 

 antennae elbowed, with usually thirteen segments ; the abdomen is con- 

 cave below and can be bent forward under the thorax. This family is some- 

 what aberrant and may come near the Proctotrypidae. It contains the 

 Ruby-wasps, which lay their eggs in bees' and wasps' nests, the Ruby- wasp 



