Disholcaspis prehensa

Weld, 1957

clasping twig gall wasp

Disholcaspis prehensa is a gall-inducing cynipid native to California that induces distinctive galls on scrub oak and leather oak. The exhibits heterogony, alternating between sexual and that produce two morphologically different gall types. The asexual generation forms conspicuous mushroom-shaped twig galls with clasping bases, while the sexual generation produces small, hidden bud galls.

Disholcaspis prehensa by (c) joergmlpts, some rights reserved (CC BY), uploaded by joergmlpts. Used under a CC-BY license.Disholcaspis prehensa by the Smithsonian. Used under a CC0 license.Disholcaspis prehensa by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Disholcaspis prehensa: /dɪs.hɒl.kæs.pɪs prɪˈhɛn.sə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

The is identified by its distinctive galls rather than . The produces mushroom-shaped twig galls 7–10 mm high and ~10 mm wide at the base, with sharp-edged bases that broadly wrap around the twig (the 'clasping' feature). These galls are red on sun-facing surfaces and yellow on shaded sides, browning with age. The sexual generation produces small (2.2–3.5 mm), oblong, light brown galls hidden within leaf buds.

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Habitat

California oak woodlands and chaparral; specifically associated with scrub oak (Quercus berberidifolia) and leather oak (Quercus durata).

Distribution

Native to California, USA.

Seasonality

emerge from twig galls in late winter to early spring and oviposit into leaf buds. Sexual adults emerge from bud galls in late spring, mate, and produce the next of twig galls that mature by early summer.

Host Associations

  • Quercus berberidifolia - scrub oak; for both
  • Quercus durata - leather oak; for both

Life Cycle

Heterogonic (). The sexual produces small, hidden bud galls on leaf buds; emerge in late spring and mate. Females oviposit into young twig tissue, forming the larger, conspicuous mushroom-shaped galls that mature by early summer. Larvae develop in elliptical chambers at the gall base and emerge as wingless, parthenogenetic females in late winter or early spring. These females reproduce without mating, completing the cycle.

Behavior

Young agamic galls induce the tree to exude honeydew-like phloem sap that attracts ants, yellowjackets, and bees. Ants are believed to protect developing larvae from .

Ecological Role

Gall inducer; modifies plant tissue to create protected feeding chambers. The galls serve as a food source and attract additional insects, potentially facilitating indirect defensive mutualisms with ants.

Similar Taxa

  • Disholcaspis quercusglobulusBoth are twig-galling Disholcaspis , but D. quercusglobulus forms round, detachable bullet galls on white oak and related species, not the clasping mushroom-shaped galls of D. prehensa
  • Disholcaspis quercusmammaAnother twig-galling with rough bullet galls; distinguished by gall and association
  • Disholcaspis plumbellaForms beaked twig galls on scrub, leather, and blue oaks; gall has different shape and color pattern

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Sources and further reading