spiny rose stem gall wasp

(Diplolepis spinosa)

Conservation Status
spiny rose stem gall wasp
  IUCN Red List

not listed

     
  NatureServe

not listed

     
  Minnesota

not listed

     
           
           
           
 
Description
 
 

Spiny rose stem gall wasp is a cynipid gall wasp. It is usually identified by the gall it produces. The gall is spherical or irregularly spherical and about in diameter, about the size of a golf ball. When found in prairies on Wood’s rose, they are weakly spined or have no spines at all. When found in woodlands on smooth rose they are densely covered with spines. When young they are green and the spines are soft. When mature they are reddish-brown or purple, hard, and woody. The gall is firmly attached to the plant and cannot be removed without snips.

Adults are to ¼ long. The males are black, the females are reddish-brown. The front segment (mesosoma) is short and strongly arched, giving a hunchback appearance.

 
     
 

Size

 
 

Gall: about in diameter

Adult: to ¼ long

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

In prairies on Wood’s rose and in woodlands on smooth rose

 
     
 
Biology
 
 

Season

 
 

One generation per year

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

In the spring the female deposits up to 16 or more eggs in a leaf bud at the base of the apical meristem. The eggs hatch after 10 to 15 days and the larvae begin feeding on stem tissue. The plant responds by producing a thick layer of stem cells around the larvae. The gall is first noticeable when it is about twice as wide as the shoot. At this phase each larva is small and eats little.

In mid-June the larva enters the maturation phase and grows rapidly, consuming all of the nutritive cells in its chamber. The gall reaches its maximum size in late June.

In mid-August the larva stops eating and enters a pre-pupa stage. It overwinters in this stage. The gall is often above the level of the snow and the insect inside is subjected to extremes of temperature. It avoids freezing by producing and accumulating glycerol.

In early spring the insect enters the white pupa stage. When the temperature reaches 54° the pupa darkens. In the spring or summer, when the buds of the host plant are growing, the adult chews an exit tunnel from its chamber and flies off in search of a mate.

The adult lives just 5 to 12 days.

 
     
 

Larva Hosts

 
 

Smooth rose (Rosa blanda var. blanda), Wood’s rose (Rosa woodsii var. woodsii), and rugose rose (Rosa rugosa) cultivars.

 
     
 

Adult Food

 
 

Adults do not feed.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 30.

 
  9/13/2019      
         
 

Occurrence

 
 

Common

 
         
 
Taxonomy
 
 

Order

Hymenoptera (ants, bees, wasps, and sawflies)  
 

Suborder

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

Superfamily

Cynipoidea (gall wasps)  
 

Family

Cynipidae (gall wasps)  
 

Subfamily

Cynipinae  
  Tribe Diplolepidini  
 

Genus

Diplolepis  
       
 

Synonyms

 
 

Diplolepis multispinosus

Rhodites multispinosus

 
       
 

Common Names

 
 

spiny rose stem gall wasp

 
       

 

 

 

 

 

Glossary

Apical meristem

Embryonic tissue at the tip of a root or the bud of a stem where cell division occurs causing growth in length.

 

Mesosoma

In Hymenoptera: the front part of the body, consisting of all three segments of the thorax and the first segment of the abdomen, to which the wings are attached.

 
 
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  Nancy
Rosemeier

7/7/2018

Location: New Prague, MN

I just cut down a rose bush full of the gall balls 

   
  Raevensong
8/15/2017

Location: Pennington County, MN

   
           
 
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