none Encapsulation of some or all of Cotesia glomerata (L.) eggs was observed in 16.7% of 779 parasitized Pieris rapae (L.) larvae in a field population. All parasitoid eggs were encapsulated in 9.8% of these larvae. Encapsulation occurred in all host instars but was rare in the first instar and became increasingly more likely with greater larval age. Second clutches of parasitoid eggs occurred in 8.0% of parasitized larvae and were most common in second instars.