Diadegma semiclausum was reared in the laboratory on 2nd and 3rd instar larvae of Plutella xylostella . At 25 degree C, the incubation period of the parasite's egg was 38 h; the following stages lasted 5.4 days (5 instars), 33 h (pre-pupa), and 5.9 days (pupa). Superparasitism occurred but only one parasite developed from one host larva. Sex ratio in D. semiclausum was found to be 1:1 in nature as well as in laboratory. The daily and total rate of eggs deposited per female were 13.6 and 164.2, respectively. The parasite male and female, fed on honey, lived for 11.2 and 14.6 days, respectively. Laboratory trials failed to rear D. semiclausum on certain lepidopterous larvae other than P. xylostella . Percentages of parasitism by D. semiclausum in P. xylostella larvae collected from cabbage fields during 1982 ranged between 0 and 66%. none