Diplolepis rosae

(Linnaeus, 1758)

Mossy Rose Gall Wasp, Rose Bedeguar Gall Wasp, Robin's Pincushion Gall Wasp

A gall-inducing in the Diplolepididae that forms distinctive mossy, pincushion-like galls on wild roses, primarily Rosa canina and Rosa arvensis. The is notable for its predominantly parthenogenetic , with fewer than 5% males in most . Females lay up to 60 in developing rose buds, inducing chemically-driven plant tissue distortion that creates the characteristic bedeguar gall. The wasp has been introduced to North America alongside cultivated roses.

Diplolepis rosae by (c) mister_bumble, some rights reserved (CC BY), uploaded by mister_bumble. Used under a CC-BY license.

Diplolepis rosae by (c) Piotr Lukasik, some rights reserved (CC BY), uploaded by Piotr Lukasik. Used under a CC-BY license.

Diplolepis-rosae by wikipedia. Used under a CC BY-SA 3.0 license.

Pronunciation

How to pronounce Diplolepis rosae: /ˌdɪpləˈlɛpɪs ˈroʊzae/

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

Identification

The can be distinguished from other Diplolepis by the female's yellow-red abdominal and leg markings on a black body, and the presence of a hypopygium. The gall is diagnostic: D. rosae produces the densely filamentous, moss-covered 'bedeguar' or 'Robin's pincushion' gall, whereas the related D. mayri induces galls with sparse, short, unbranched filaments typically on twigs rather than buds. Gall location also differs: D. rosae galls form predominantly on leaf axils (85.1%) and shoot sides (63.5%), with fewer on flowers/fruits and shoot tips.

Images

Habitat

Heathland, scrubland, and hedgerows supporting wild rose shrubs; in North America also found in parks and gardens with cultivated roses. Galls occur more frequently on plants under stress from drought, waterlogging, or damage, and on younger or damaged plants rather than vigorous, intact specimens. Laboratory rearing successful on multiple Rosa under controlled conditions.

Distribution

Native to Europe; introduced to North America. Recorded from Belgium, Canada, Czech Republic (Brno region), France, Hungary, Romania, and other European countries. GBIF records confirm presence in Belgium and Canada.

Seasonality

emerge from galls primarily in May, with emergences continuing through August in some . laid May-July; first instar larvae June-August; second instar July-October or March depending on climate; pupae present mid-March to mid-July. Gall growth most rapid June-July, completing by October.

Host Associations

Rosa canina - primary dog rose
Rosa arvensis - primary field rose
Rosa rubiginosa - secondary sweet briar rose
Rosa dumalis - secondary
Rosa rubrifolia - secondary
Rosa gallica - laboratory
Rosa spinosissima - laboratory
Periclistus brandtii - found in 10% of galls, 3.6% of ; harmless co-occupant
Eurytoma rosae - attacks both D. rosae and P. brandtii larvae
Glyphomerus stigma - attacks both D. rosae and P. brandtii larvae
Orthopelma mediator - ichneumon that lays directly into D. rosae larvae
Caenacis inflexa - hyperparasitoid
Pteromalus bedeguaris - hyperparasitoid

Life Cycle

Females lay singly on epidermal within developing rose buds using a specialized ovipositor inserted between leaflets. Larval feeding stimulates plant to produce enlarged 'nutritive' cells that are continually replaced and consumed. Five larval instars; development rate and hibernation stage climate-dependent. In warm/dry conditions, 70% overwinter as and 30% as second instar larvae; in milder conditions, 47% prepupae and 53% larvae. Prepupa undergoes final moult to pupa in February-March. emerge May-July. No ; primarily parthenogenetic year-round in laboratory conditions.

Behavior

Females use modified ovipositor to deposit between developing leaflets of expanding buds. Gall formation involves rapid tissue proliferation June-July, with concentric layers developing around a nutritive core. Galls positioned closer to ground produce higher success. Larger galls show reduced rates relative to gall volume. Vertebrate occasionally break open mature galls to access larvae/pupae.

Ecological Role

Gall formation creates complex microhabitat supporting diverse of , , and hyperparasitoids. Acts as natural control on wild roses by redirecting plant resources into gall tissue. Nutrient cycling through approximately 50% preimaginal mortality. Associated parasitic fungus Phragmidium subcorticum frequently attacks gall tissues.

Human Relevance

Subject of extensive folklore; names 'bedeguar' and 'Robin's pincushion' reflect cultural significance. No economic damage to roses despite gall formation; galls cause only cosmetic effects. Used in laboratory studies of gall induction, - interactions, and evolution of . Potential biocontrol interest for related pest .

Similar Taxa

Diplolepis mayriAlso induces galls on roses, but produces sparsely filamented, twig-based galls with short unbranched filaments rather than dense mossy structures; historically less common and more suited to laboratory rearing
Other Cynipidae/DiplolepididaeNumerous gall wasps induce rose galls, but D. rosae is distinguished by the unique bedeguar and specific associations

More Details

Reproductive biology

Two distinct genetic lineages identified in French , differing 13.2-fold in rate and 1.6-fold in heterozygosity. The higher-recombination lineage shows purifying selection on male trait genes, suggesting maintenance of capacity despite predominant thelytoky. endosymbiont implicated in female-biased sex ratios through manipulation.

Gall architecture

Galls consist of 1-20 intergrown parts (mean 7) containing 1-225 (mean 54). Cell size varies by inhabitant: largest cells (3.9×3.1 mm) contain successfully developing gall wasps. Optimal clutch size appears to be 25-30 chambers based on success, with secondary peak around 60 chambers.

Historical notes

First described by Linnaeus in 1758 as Cynips rosae. Subject of early biological study by Alfred C. Kinsey, who began his scientific career with two decades of cynipid research before his famous human sexuality work.