The effect of multiple immersions on Haemagogus janthinomys Dyar, 1921 eggs and the development of its immature forms were studied. Eggs of Hg. janthinomys from Linhares (state of Espírito Santo) were submitted to multiple immersions, counting the number of hatched eggs and observing the periods for development until adult. The egg-hatching proportion attained 42–88% (mean=68.2%), after 16 immersions, in three trials. After 8–9 immersions, the effect of additional immersions was negligible. The periods for development of immature forms were 3.67±0.89, 1.2±0.66, 1.12±0.63, 4.86±1.77, 2.25±0.67 and 12.40±0.82 days, respectively for 1st-4th instar larvae, pupae and the total. The postponement of the egg-hatching can be important for the production of mosquitoes, from one egg batch, during several months. The total period of larval development is very similar to previous indirect field calculations in the Brazilian state of Para and to mosquitoes from Panama studied in the laboratory.