Morph-determination
Guides
Adelges laricis
Larch Woolly Aphid
Adelges laricis is a holocyclic adelgid with a complex life cycle involving two host genera: Picea (spruce) as primary host where galls form, and Larix (larch) as secondary host. The species exhibits extensive morphological polymorphism across five generations (Fundatrix, Migrans alata, Hiemosistens, Sexupara, Sexualis). First-instar nymphs are the only mobile stage; subsequent instars remain sessile with stylets permanently inserted. The species is a significant forest pest causing reduced tree vigor, needle damage, and mortality under chronic infestation.
Melittobia
Melittobia is a genus of tiny parasitoid wasps in the family Eulophidae, notable for extreme polymorphism, complex social behaviors, and highly female-biased sex ratios. Females exhibit three distinct morphs—winged 'fliers,' short-winged 'jumpers,' and wingless 'crawlers'—determined by larval density rather than genetics. Males are blind, flightless, and comprise only about 5% of offspring, produced asexually through arrhenotokous parthenogenesis. The genus attacks prepupae and pupae of solitary bees, wasps, and other insects in their hosts' nests, with some species also parasitizing fruit flies and flesh flies. Several species are well-studied model organisms for genetics, developmental biology, and behavioral ecology, though taxonomic confusion persists due to extreme morphological plasticity.