Oak Marble Gall Wasp - Andricus kollari

Alternative names
Oak Marble Gall
Description

Length 1.5 to 2mm. The male wasp is very dark brown to black on the head has a hunched thorax, with a black abdomen. The legs are yellowy brown and the antennae are a translucent yellow/brown colour. The female has a dark brown appearance overall.

The gall is seen more often than the adult wasp.  The agamic galls are the very common and familiar marble galls, large spherical  galls that start green and become brown and very hard, persisting for years in some cases.  There is a single larval chamber inside, although inquilines are also common in the gall tissue. They form on the buds of native Pedunculate and Sessile Oaks (Quercus robur and Q petraea).

The small sexual gall is found on the buds of the Turkey Oak.  It is ovoid with a pointed tip, but rarely recorded.

Similar Species

Recently, Andricus infectorius galls have been found on two sites in the Charnwood Forest.  (see Leach,C. 2020 Andricus infectorius (Hartig,1843): Biology, History & its occurrence in Britain. Cecidology 35 (1): 22-26.)

It is very similar to A kollari, described in the above as 'when young, the galls are green with raised pale yellowish bumps . . as they mature they become reddish brown and although the outer surface becomes crinkled and slightly pliable, the galls beneath are extremely hard and woody.'

Sam J Buckton (Cecidology 37 (1): p.13) describes it as having 'a narrowing by the attachment point, and a slight raised ridge connecting the pimples’.

Several other species cause small sexual galls in Turkey Oak buds.

 

Identification difficulty

Agamic gall Sexual gall Adult

Habitat

Anywhere that the host oak is found.

When to see it

Adult females exit Oak Marble Galls from August to October.

UK Status

Common throughout Britain.

VC55 Status

Common in Leicestershire and Rutland.

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map

Species profile

Common names
Marble Gall
Species group:
Bees, Wasps, Ants
Kingdom:
Animalia
Order:
Hymenoptera
Family:
Cynipidae
Records on NatureSpot:
249
First record:
24/05/2006 (Calow, Graham)
Last record:
23/02/2024 (Smith, Peter)

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