Results of the tests where a further improvement of our current in vitro rearing system for the hymenopteran (Pteromalidae) ectoparasitoid Catolaccus grandis (Burks) was attempted indicated that: 1) Frequent recurring bacterial and fungal contamination of the standard parasitoid larval diet was greatly diminished by replacing the antibiotic gentamicin with a wide spectrum antibiotic mixture containing penicillin, streptomycin and amphotericin plus a mixture of propionic and phosphoric acids. 2) The costly Parafilm® membrane used to cover the rearing chambers (Multiwell® tissue culture plates), and to collect parasitoid ovipositions was replaced by a commercially available polyethylene plastic membrane. The membrane is transparent, more efficient (collects higher numbers of eggs) and ca. 55 x cheaper than Parafilm®. 3) Dislodging parasitoid eggs deposited by C. grandis at the inner surface of the membrane covers onto the diet by tapping firmly the rearing chambers on the palm of a hand, reduced adult yield. The percentage of C. grandis completing development to the adult stage increased when the membrane covers with eggs were left in place for 48 h. 4) Volatiles emanating from our basic parasitoid larval diet induced C. grandis females to lay eggs, but some smears of the short chain alkane, n-hexane, on rearing plate covers stimulated stronger ovipositional responses. However, greater egg depositions were induced when the diet and n-hexane were combined than with either of those stimulants alone.