Eggs of arthropods and non-mammals vertebrates require a large amount of nutritional reserve to the embryo development. Vitellins are the most important yolk protein accumulated during oogenesis in organelles called yolk granules. In several arthropods, including insects, some lysosomal enzymes have been described being responsible for yolk mobilization like proteinases and acid phosphatases. These hydrolases could be activated by yolk granules acidification during embryogenesis. In this work we described two classes of proteinases during early embryogenesis of P. americana. We detemined the proteolytic profile of yolk proteins and activation by acidification. In parallel, we showed the acid phosphatase activity profile. Yolk granules were extracted from ootheca, collected from each day after oviposition, and prepared for hydrolase activity. Proteinase activity was detected by using a general fluorescent substrate (phe-arg-MCA) and phosphatase activity using a colorimetric assay with pNPP (synthetic substrate for general phosphatases). We showed the level changes in proteinase and acid phosphatase activities during early embryogenesis until the gastrulation time. Profiles were coincident, beginning at day 6 with a peak at the day 10 after oviposition. Analyses using different inhibitors suggest the presence of a serine proteinase inhibited by aprotinin and a cysteine proteinase, which was inhibited by E-64. We showed, in day 10 after oviposition, the pH curve for each proteinase, acid for cysteine proteinase and neutral for serine proteinase. Proteinase activity was not able to degradate arg-arg-MCA, suggesting a cathepsin-L proteinase. Incubation of samples from day 3 and day 6 after oviposition in acidic pH revealed an activation of proteinase activity. The phosphatase activity was due to the acid tyrosine phosphatase which could be inhibited by ammonium molibdate, sodium tartrate and NaF. A dependency relationship between both hydrolases is under investigation for our group.