oak rough bulletgall wasp

(Disholcaspis quercusmamma)

Conservation Status
IUCN Red List

not listed

NatureServe

not listed

Minnesota

not listed

 
oak rough bulletgall wasp
 
Description

Oak rough bulletgall wasp is a cynipid gall wasp. It is usually identified by the gall it produces. In Minnesota, galls are found in clusters on the twigs and branches of bur oak and swamp white oak. They first appear as green bumps on the twig. The bumps later turn bright red. As they grow into round galls, they turn light brown and are soft. Eventually, they turn dark brown and harden. Mature galls are 5 16 to in diameter, woody, and spherical, with a nipple-like, obscure point at the top. They produce honeydew that attracts bees, and wasps, and ants, which protect the gall wasp from other parasitic wasps. Each gall contains only a single wasp, though they may be shared by other species (inquilines). A small, circular hole in the side of a gall indicates where the wasp has emerged.

The galls remain on the tree up to five years after the wasp has left the gall. They do not kill the host stem but will reduce the growth of the infested tree.

 

Size

Galls: 5 16 to in diameter

 

Similar Species

 
Habitat

Anywhere the host species are found

Biology

Season

One generation per year, late October to early November

 

Behavior

 

 

Life Cycle

The life cycle of this wasp involves alternation of generations, one generation with only asexual females and one generation with both sexual males and sexual females. Information is only available for the asexual generation. The sexual generation has not been described in entomological literature.

The female lays eggs in a dormant, terminal bud at the tip of a twig. In the late spring of the following year, the larva stimulates the growing stem to produce a gall in which the wasp develops. The larva pupates within a small cell in the center of the gall. In Minnesota, adults emerge in September. In the asexual generation, both winged and wingless females are produced. Males are unknown.

 

Larva Hosts

bur oak, swamp white oak

 

Adult Food

Adult wasps do not feed

Distribution

Distribution Map

 

Sources

7, 24, 27, 29, 30, 82, 83.

3/23/2025    
     

Occurrence

Common

Taxonomy

Order

Hymenoptera (ants, bees, wasps, and sawflies)

Suborder

Apocrita (narrow-waisted wasps, ants, and bees)

Infraorder

Proctotrupomorpha

Superfamily

Cynipoidea (gall wasps and allies)

Family

Cynipidae (gall wasps)

Subfamily

Cynipinae

Tribe

Cynipini (oak gall wasps)

Genus

Disholcaspis

   

Subordinate Taxa

 

   

Synonyms

Disholcaspis mamma

   

Common Names

oak rough bulletgall wasp

 

 

 

 

 

 

 

 

Glossary

Inquiline

An animal that lives in the nest of an animal of another species.

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Alfredo Colon

oak rough bulletgall wasp    
     
eastern black carpenter ant   eastern black carpenter ant

Babette Kis

oak rough bulletgall wasp

Oak rough bulletgall wasp

Many galls on this particular bur oak, which was sapling size.

MinnesotaSeasons.com Photos
oak rough bulletgall wasp    
     
oak rough bulletgall wasp   oak rough bulletgall wasp
     
oak rough bulletgall wasp   oak rough bulletgall wasp
     
oak rough bulletgall wasp   oak rough bulletgall wasp
     
oak rough bulletgall wasp   oak rough bulletgall wasp

 

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Other Videos

Oak bullet galls & ants
Waterman's STNY Nature

About

Aug 14, 2022

Oak rough bullet galls are formed on Swamp oak branches by the cynipid wasp Disholcaspis quercusmamma. The specific epithet referring to the "mammal-like" (breast-like) look. They also remind me of peaches, both by their red blush and the "fuzz". The gall tweaks the oak's programming to cause nectar production, which attracts Carpenter ants, who then patrol and feed. The enemies of the little larva inside each gall are then kept at bay by the ant guards. Potentially, the oak also benefits from the reduction of herbivory the ant's stewardship provides. Ants, cynipid wasps, and oak trees. (Apalachin Marsh, Apalachin, NY. August 2022, jcs.)

 

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Alfredo Colon
8/7/2022

Location: Albany, NY

eastern black carpenter ant

Alfredo Colon
8/6/2022

Location: Albany, NY

oak rough bulletgall wasp
Babette Kis
10/13/2020

Location: hedgerow at Barnes Prairie, Racine Co., WI

Many galls on this particular bur oak, which was sapling size.

oak rough bulletgall wasp
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Created 3/18/2019

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