Summary..Studies of the biology of two species ofEmpriaLep.,E. abdominalisF. andE. tridensKon., reveal thatE. abdominalisis a multivoltine species with thelytokous parthenogenesis andE. tridensis a univoltine species with arrhenotokous parthenogenesis.E. abdominalisis associated withAnagallisandLysimachia,and lays large conspicuous eggs in the under sides of the leaves.E. tridensfeeds onRubusspp., and inserts small inconspicuous eggs into stems, leaves, and bud scales of the host plant.Larvae of both species are closely and evenly annulated. A typical abdominal segment has six annulets; inE. abdominalisthe second and fourth annulets are setiferous, while inE. tridensthe first, second, and fourth annulets are setiferous. Prolegs occur on segments 5–11 and 13 in both species and pseudocerci are absent. Larvae ofE. abdominalishave the back and sides covered with a fine flaky or powdery substance which is absent in larvae ofE. tridens.Females ofE. abdominalishave six larval stages, in the last of which no feeding takes place. Males ofE. tridenshave five larval stages, in all of which feeding occurs.InE. tridenshibernation and pupation take place within bark, dead wood, and pithy stems, while inE. abdominalispupation takes place in the soil. Neither species constructs a cocoon.The differences in biology and habits seem to justify the subdivision of the genus by Enslin into subgenera–MonostegiaCosta, which includesE. abdominalis,andTriempriaEnslin, which includesE. trid