Oviposition and development of Evania appendigaster and Tetrastichus hagenowii in live P. americana oothecae ranging in age from 0–44 days was investigated. E. appendigaster oviposited in oothecae of all ages but developed only in 0–28 days old oothecae. T. hagenowii oviposited only in oothecae 0–34 days old, but developed only in 0–28 days old oothecae. Oothecae parasitized by E. appendigaster were superparasitized only during the first 4 days after the initial parasitization. A single parasite emerged from each such oothecae, indicating that only one of the two ovipositions was successful. Oothecae superparasitized by T. hagenowii during the first 8 days of the initial parasitization, resulted in ca. 90 parasites from both ovipositions. Oothecae parasitized by each species of parasite were subjected to multiple parasitism by the other species. Oviposition of E. appendigaster in 0–25 days old oothecae, parasitized by T. hagenowii was ineffective as it resulted in the emergence of T. hagenowii only. Reparasitization of 0–36 days old E. appendigaster-parasitized oothecae by T. hagenowii within 0–32 days resulted in the development of T. hagenowii, but reparasitization thereafter was ineffective as only E. appendigaster emerged. Even though T. hagenowii is more efficient than E. appendigaster, in parasitizing and developing in different types of P. americana oothecae, under field conditions the two species of parasites contribute equally towards the natural control of P. americana.