Polyphenism
Guides
Acyrthosiphon pisum
Pea aphid, green dolphin, pea louse, clover louse
Acyrthosiphon pisum, the pea aphid, is a sap-sucking hemipteran and major agricultural pest of legume crops worldwide. It is notable as the first hemimetabolous insect with a fully sequenced genome and serves as a model organism for studying aphid biology, endosymbiosis, polyphenism, and asexual reproduction. The species exhibits complex polyphenism with multiple morphs including winged and wingless parthenogenetic females, sexual males and females, and green or red/pink color morphs. Its survival depends entirely on the obligate endosymbiont Buchnera aphidicola, which provides essential amino acids lacking in its phloem sap diet.
Aphis rubicola
Aphis rubicola is a species of aphid in the family Aphididae, described by Oestlund in 1887. The species exhibits holocyclic life cycle with seasonal polyphenism, producing sexual morphs (males and oviparae) in response to short-day photoperiods. Laboratory studies demonstrate that temperature significantly modifies sexual morph production, with lower temperatures enhancing the transition to sexual reproduction. The specific epithet suggests association with Rubus (raspberry/blackberry) as a host plant, though this has not been explicitly confirmed in available sources.
Prociphilus
Woolly Aphids
Prociphilus is a genus of woolly aphids in the family Aphididae, subfamily Eriosomatinae, comprising approximately 50 species. These aphids are notable for inducing gall formation on host plants, within which they reside and feed. The genus exhibits complex life cycles including host alternation and polyphenism, with multiple distinct morphs adapted to different hosts and conditions. Several species have documented mutualistic relationships with ants, and some display remarkable seasonal phenomena such as the mass emergence of Prociphilus oriens in Japan, which is culturally associated with the first snowfall.
Schistocerca americana
American grasshopper, American bird grasshopper
Schistocerca americana is a large grasshopper native to eastern North America, Mexico, and the Bahamas. Adults reach 4.5–5.5 cm in length, with yellow-brown bodies and pale wings marked with large brown spots. The species exhibits temperature-dependent color polyphenism in nymphs, producing green, yellow, or red forms with black patterning influenced by thermal conditions. Two generations occur annually, with adults overwintering rather than eggs. Though occasionally called a 'locust' during localized outbreaks, it lacks the true swarming morph of its congener S. gregaria.
Sphecophaga vesparum
Sphecophaga vesparum is an ichneumonid ectoparasitoid of vespid wasps, primarily targeting Vespula vulgaris and Vespula germanica. The species exhibits remarkable developmental plasticity with two adult female morphs: large winged females and small brachypterous females, each emerging from distinct cocoon types. It has been introduced to New Zealand and Australia as a biological control agent for invasive social wasps. The species is facultatively deuterotokous, producing mostly parthenogenetic females with occasional males.