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The size of the extracellular spaces revealed by Evans' blue penetration into the follicular epithelium of Rhodnius prolixus increases with the stage of vitellogenesis. This was found to be true of follicles incubated in control media, as well as those whose spaces had been stimulated to expand by incubation in juvenile hormone (JH) or the analogue ZR515. An improved method of estimating hormonal effects in vitro utilizes a regression analysis of patency index relative to follicle length; with control follicles the slope was 0.44, whereas hormone- and analogue-treated follicles yielded slopes of 0.86 and 1.09, respectively. Some pitfalls of the dye penetration test are outlined.

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Exogenous juvenile hormone (JH) application to Schistocerca gregaria eggs interfered with normal embryogenesis in a dose- and age-dependent manner. Embryos treated between 3 to 9 days postoviposition were inhibited at (1) blastokinesis; (2) postblastokinesis; (3) as vermiform larvae; or (4) as first-instar hoppers unable to shed their provisional entitle completely. The development of 3- to 5-day-old embryos was inhibited at blastokinesis when the embryos were treated with 1 μg JH but not with 0.1 μg JH. However, sensitivity increased with age, so that 8-to 9-day-old embryos were unable to shed the provisional cuticle when treated with as low as 0.01 μg JH. Treatment of embryos later than 10 days after oviposition did not disrupt embryogenesis and did not result in postembryonic aberrations at any stage in the life cycle. Furthermore, exogenous JH treatment of developing embryos did not enhance solitarization of S. gregaria.Disruption of embryogenesis was accompanied by an increase in brown coloration of the embryos. Microscopic examination revealed an interference with the normal development of the provisional cuticle.