Psylla

Geoffroy, 1762

jumping plant lice, psyllids

Species Guides

Psylla is the type of the Psyllidae, comprising small sap-sucking insects commonly known as jumping plant lice or psyllids. The genus contains at least 110 described , each typically associated with specific plants. Psylla species are phloem-feeders that use to extract plant sap. While some species in related genera such as Cacopsylla are significant agricultural pests, Psylla itself includes species with more restricted host ranges, including Psylla alni on alders, Psylla betulae on birches, and Psylla buxi on boxwood. The genus is distinguished from similar by morphological features and host associations.

Psylla carpinicola by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.

Psylla viridescens by (c) christine123, some rights reserved (CC BY), uploaded by christine123. Used under a CC-BY license.

Pronunciation

How to pronounce Psylla: /ˈsɪlə/

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Identification

Distinguished from barklice (Psocodea) by rather than chewing mouthparts. Separated from aphids (Aphididae) by more robust body form, jumping ability, and different wing venation. Distinguished from whiteflies (Aleyrodidae) by wing posture (roof-like vs. flat) and body shape. Differentiated from the closely related and economically important Cacopsylla by subtle morphological features of the , genitalia, and wing characters requiring microscopic examination; Cacopsylla are generally more significant fruit tree pests.

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Habitat

Associated with woody plants including alders (Alnus), birches (Betula), boxwood (Buxus), limes (Tilia), and kōwhai (Sophora). Inhabits foliage of host plants where nymphal development occurs. may disperse to non-host plants during seasonal movements but require specific host plants for .

Distribution

Widespread across temperate regions of the Northern Hemisphere including Europe, Asia, and North America. Specific distribution varies by ; for example, Psylla alni occurs on alders across Europe, while Psylla frodobagginis is restricted to New Zealand on kōwhai trees. GBIF records indicate presence in Norway and Sweden.

Seasonality

Seasonal activity tied to plant . typically emerge in late summer to fall. strategies vary; some overwinter as adults seeking shelter in protected locations. -laying synchronized with host plant bud break in spring; precise timing critical for offspring survival.

Diet

Phloem sap extracted from plants using . Feeding restricted to specific host plant or closely related within a plant .

Host Associations

Alnus (alders) - obligatePsylla alni, the type
Betula (birches) - obligatePsylla betulae
Buxus (boxwood) - obligatePsylla buxi
Tilia (limes/lindens) - obligatePsylla cordata
Sophora (kōwhai) - obligatePsylla apicalis and Psylla frodobagginis
Albizia odoratissima - obligatePsylla oblonga

Life Cycle

Development occurs through , five nymphal instars, and stages. Eggs deposited on plant foliage, typically on developing leaves. Nymphs feed on host plant phloem, completing five instars on the foliage. Some induce gall formation on host leaves; nymphs develop within protective galls. Adults emerge from galls or from final nymphal skins, disperse, mate, and seek sites or continue depending on species and climate.

Behavior

are strong fliers and capable of jumping to escape . Seasonal between reproductive and transitory hosts observed in some ; feeding on transitory hosts sustains survival but does not support . Precise timing of -laying synchronized with host plant critical for offspring success. Some species form on host plants; others more solitary.

Ecological Role

Herbivores that extract phloem sap from plants, potentially causing direct damage through feeding and indirect effects through honeydew production. Serve as prey for various natural enemies including predatory (Anthocoris spp.), lacewings, and (Psyllaephagus spp., Torymus spp.). Some induce plant gall formation, creating microhabitats that support complex including parasitoids and .

Human Relevance

Generally less economically significant than related such as Cacopsylla, which includes major fruit tree pests. Some Psylla may cause minor damage to ornamental plants including boxwood and linden. Psylla alni and related species occasionally reach nuisance levels when aggregate on building exteriors seeking shelter. Subject of taxonomic and ecological research due to -specificity patterns and role in understanding evolution.

Similar Taxa

CacopsyllaClosely related containing most harmful to fruit trees; distinguished by subtle morphological differences in structure, genitalia, and wing characters
TriozaRelated in Triozidae; distinguished by different wing venation and associations
AcizziaRelated including such as Acizzia jamatonica (Albizia fly); distinguished by associations and morphological features
Pachypsylla of hackberry psyllids that induce distinctive nipple galls on Celtis leaves; distinguished by gall-forming and specificity to hackberry

Misconceptions

The 'jumping plant lice' sometimes leads to confusion with true (), which are unrelated parasitic insects. Psyllids are sometimes mistakenly called 'flies' in agricultural contexts, though they belong to order Hemiptera, not Diptera. Many economically damaging 'psyllas' have been reclassified from Psylla to Cacopsylla or other , leading to outdated in older literature.

More Details

Etymology

The name Psylla derives from the Greek psulla, meaning , referring to the jumping ability of these insects.

Taxonomic history

Psylla was established as the type of Psyllidae. The type Psylla alni was originally described as Chermes alni by Linnaeus in 1758. Modern has moved many economically important species formerly placed in Psylla to related genera, particularly Cacopsylla.

Research significance

Psylla serve as model organisms for studying -specificity in phytophagous insects, with each species typically restricted to one or a few closely related host plants. This pattern has made psyllids valuable for studies of and ecological specialization.