Host-alternating
Guides
Brachycaudus cardui
thistle aphid, plum-thistle aphid
Brachycaudus cardui is a heteroecious aphid species with a complex life cycle alternating between primary woody hosts (Prunus spp.) and secondary herbaceous hosts, primarily thistles and other Asteraceae. Wingless viviparous females are small (1.8–2.5 mm), oval to pear-shaped, and variable in color. The species is notable for causing leaf roll on Prunus and for transmitting plum pox virus, a serious agricultural pathogen. Colony establishment depends heavily on ant attendance.
Colopha graminis
Colopha graminis is a gall-forming aphid in the family Aphididae, closely related to the well-studied elm cockscomb gall aphid Colopha ulmicola. Like other members of the genus Colopha, this species exhibits a complex life cycle involving host alternation and gall formation on its primary host, followed by migration to grass roots for summer feeding. The species was described by Monell in 1882 and belongs to the subfamily Eriosomatinae, a group characterized by their tendency to induce plant galls and their often elaborate seasonal host-switching behaviors.
Grylloprociphilus
woolly beech aphid, boogie-woogie aphid, beech blight aphid
Grylloprociphilus is a genus of woolly aphids in the family Aphididae, established by Smith & Pepper in 1968. The genus contains at least one described species, G. imbricator, commonly known as the woolly beech aphid or boogie-woogie aphid. These aphids are notable for producing dense white waxy secretions that cloak host tree branches, and for their distinctive defensive behavior of synchronized posterior swaying when disturbed. The genus exhibits heteroecious holocyclic life cycles with host alternation between primary and secondary hosts.
Hyalopterus pruni
Mealy Plum Aphid
Hyalopterus pruni, the mealy plum aphid, is a sap-feeding aphid in the family Aphididae with a cosmopolitan distribution. It exhibits a complex life cycle involving multiple generations of wingless adults followed by the production of winged migrants that disperse to secondary hosts. The species is notable for its waxy covering and seasonal host alternation between Prunus species and grasses or reeds.
Hyperomyzus lactucae
Sowthistle Aphid, Blackcurrant-sowthistle Aphid
Hyperomyzus lactucae is a European aphid species in the family Aphididae, commonly known as the sowthistle aphid or blackcurrant-sowthistle aphid. The species exhibits a host-alternating life cycle, utilizing Sonchus species (sowthistles) as primary hosts and Ribes nigrum (blackcurrant) as a secondary host. It is a known vector of lettuce necrotic yellows virus and has been introduced to Australia as a pest of lettuce crops. Development, survival, and reproduction are strongly influenced by temperature and photoperiod, with faster development at higher temperatures within a range of approximately 12.5–24°C.
Hyperomyzus pallidus
Gooseberry-Sowthistle Aphid
Hyperomyzus pallidus is a species of aphid in the family Aphididae, first described by Hille Ris Lambers in 1935. It is commonly known as the Gooseberry-Sowthistle Aphid, reflecting its association with host plants in the genera Ribes (gooseberries and currants) and Sonchus (sowthistles). The species exhibits the typical aphid life cycle with alternating hosts, though specific details remain incompletely documented. It has been recorded from parts of Europe and North America.
Macrosiphum euphorbiae
potato aphid
Macrosiphum euphorbiae, commonly known as the potato aphid, is a polyphagous sap-sucking insect in the family Aphididae. It is a globally significant agricultural pest, particularly of potato (Solanum tuberosum), tomato, lettuce, and numerous other crops across more than 20 plant families. The species exhibits complex life cycle strategies including host alternation between primary (Rosa spp.) and secondary hosts, cyclical parthenogenesis in North America, and obligate asexual reproduction in UK populations. It vectors multiple plant viruses including potato leaf roll virus, potato virus Y, and tomato yellow top virus. The aphid demonstrates notable phenotypic plasticity with green and pink color morphs, and possesses distinctive antipredator behaviors including dropping from host plants followed by tonic immobility.
Pachypappa
Pachypappa is a genus of aphids in the family Aphididae, first described by Koch in 1856. The genus is currently considered valid, though some sources list it as a synonym of Cornaphis. Species are distributed across Europe and North America, with confirmed records from Denmark, Norway, and Sweden.
Pemphigus bursarius
lettuce root aphid, poplar gall aphid
Pemphigus bursarius is a host-alternating aphid with a heteroecious life cycle involving Populus species as primary hosts and Asteraceae (particularly lettuce) as secondary hosts. On poplars, it forms flask-shaped leaf-stalk galls in spring; on secondary hosts, it lives subterraneanly feeding on roots. The species exhibits unusual flexibility in its life cycle, with some populations capable of asexual overwintering in soil without returning to the primary host. It is an economically significant pest of lettuce crops and shows genetically distinct host-associated populations.
Pemphigus populitransversus
poplar petiole gall aphid, cabbage root aphid
Pemphigus populitransversus is a gall-forming aphid that induces distinctive fleshy galls on the petioles of poplar leaves. The species exhibits a complex life cycle involving alternation between primary hosts (Populus species) and secondary hosts in the Brassicaceae family. On poplars, females induce green or red galls up to 14 mm in diameter at leaf bases, where they lay eggs; a slit in the gall allows aphid exit. On Brassica hosts, the aphid forms root galls. Adults are small (1.6–2.6 mm) and morphologically distinct from other aphids in lacking abdominal cornicles and having relatively short antennae and legs.
Rhopalosiphum nymphaeae
waterlily aphid, water lily aphid
Rhopalosiphum nymphaeae, the waterlily aphid, is a cosmopolitan, host-alternating aphid species with a unique ability to thrive in both aquatic and terrestrial environments. It is a significant agricultural pest that damages crops through direct herbivory and as a vector for plant viruses, particularly affecting Prunus spp. fruits and various aquatic plants. The species exhibits complex life history traits including rapid population growth (intrinsic rate of increase 0.315 day⁻¹, doubling time 2.2 days) and strong host preferences among aquatic vegetation.
Tetraneura ulmi
elm sack gall aphid, fig gall aphid
Tetraneura ulmi, commonly known as the elm sack gall aphid or fig gall aphid, is a gall-forming aphid in the family Aphididae. First described by Linnaeus in 1758, this species induces distinctive club-like pouch galls on elm leaves. The aphid exhibits a complex life cycle involving alternation between primary elm hosts and secondary grass hosts. Founding mothers stimulate gall formation through sap-sucking behavior, creating a protected environment for their offspring. The species is distributed across Asia, Europe, and North America, with particular dominance in northwestern Europe.
Trioza
psyllids, jumping plant-lice
Trioza is the type genus of psyllids in the family Triozidae, comprising sap-sucking insects with worldwide distribution. Species in this genus exhibit diverse host associations, ranging from agricultural crops to native trees. Several species are economically significant: Trioza erytreae transmits citrus greening disease (Huanglongbing), T. apicalis is a major pest of carrot in northern Europe, and T. brevigenae is an invasive pest of ornamental Ficus in California. The genus is characterized by distinct morphological features and complex life cycles involving seasonal migration between summer hosts and overwintering sites.