that fueled further debate in the field of evolution and development was the proposal that the hemimetabolan nymphal stages are equivalent to the holometabolan pupal stage. Critics of this theory (most notably H. E. Hinton) argue that post-embryonic development in hemimetabolans and holometabolans are equivalent, and rather the last nymphal instar stage of hemimetabolans would be homologous to the holometabolan pupae. More modern opinions still oscillate between these two conceptions of the hemi- to holometabolan evolutionary trend. J.W. Truman and L.M. Riddiford, in 1999, revitalized the precocious eclosion theory with a focus on endocrine control of metamorphosis. They postulated that hemimetabolan species hatch after three embryonic "moults" into a nymphal form similar to the adult, whereas holometabolan species hatch after only two embryonic 'moults' into vermiform larvae that are very different from the adult. In 2005, however, B. Konopová and J. Zrzavý reported ultrastructural studies across a wide range of hemimetabolan and holometabolan species and showed that the embryo of all species in both groups produce three cuticular depositions. The only exception was the Diptera Cyclorrhapha (unranked taxon of "high" Dipterans, within the infraorder Muscomorpha, which includes the highly studied Drosophila melanogaster) which has two embryonic cuticles, most likely due to secondary loss of the third. Critics of the precocious eclosion theory also argue that the larval forms of holometabolans are very often more specialized than those of hemimetabolans. X. Belles illustrates that the maggot of a fruitfly "cannot be envisaged as a vermiform and apodous (legless) creature that hatched in an early embryonic stage." It is in fact extremely specialized: for example, the cardiostipes and dististipes of the mouth are fused, as in some mosquitoes, and these parts are also fused to the mandibles and thus form the typical mouth hooks of fly larvae. Maggots are also secondarily, and not primitively, apodous. They are more derived and specialized than the cockroach nymph, a comparable and characteristic hemimetabolan example. More recently, an increased focus on the hormonal control of insect metamorphosis has helped resolve some of the evolutionary links between hemi- and holometabolan groups. In particular, the orchestration of the juvenile hormone (JH) and ecdysteroids in molting and metamorphosis processes has received much attention. The molecular pathway for metamorphosis is now well described: periodic pulses of ecdysteroids induce molting to another immature instar (nymphal in hemimetabolan and larval in holometabolan species) in the presence of JH, but the programmed cessation