The interior of a bedeguar gall is formed from the bud, and is composed of edible nutritious and structural tissues.

This structure gives the appearance of a ball of moss, and its filaments are often brightly colored, being at their best around September; starting off green and then passing through pink and crimson to reddish brown.

This activity stimulates (in a way not yet understood) the development by the host plant of enlarged 'nutritive' cells in the area around the growing larva.

Through the thin, transparent skin of the pupa, it is possible to see the fully formed antennae, legs, wings and body segments of the adult wasp.

The large size of the emergence holes of the individual cells sometimes suggests predation by birds or small mammals has taken place.

[15][16][17] The cynipid wasp Periclistus brandtii is an inquiline that lives harmlessly within the bedeguar gall and like Diplolepis rosae itself, is often parasitised by insects referred to as parasitoids or even by hyperparasitoids in some cases.

[18] The gall-wasp Periclistus brandtii causes no gall itself, but deposits its eggs in the bedeguar tissues on which the larvae feed.

The mossy and sticky filaments of the gall are clearly ineffective in preventing the entry of inquilines, predators, parasitoids and hyperparasitoids.

[19] The tissues of the bedeguar gall are frequently attacked by the parasitic fungus Phragmidium subcorticum, more so than the other parts of the host rose plant.

Whether the vigorous plant suppresses gall formation or is avoided by the wasp in favor of easier targets is unknown.

Thus, it seems more effective for a female D. rosae to induce larger galls on lower branches of the shrubs to increase the survival probability of the offspring.

Dried and powdered, the gall was used to treat colic,[6] as a diuretic, and as a remedy against toothache; the ashes mixed with honey and applied to the scalp were thought to prevent baldness.

[21] It was also valued as an astringent and for its ability to control fluid loss; placed beneath a pillow, it was thought to induce sleep.