Rose bedeguar gall

Appearance

The female insects are about 4 mm long; parts of their abdomens and legs are yellow-red, while the rest of their bodies are black. The male is black and lacks the hypopygium structure which clearly identifies the species in the female. Its legs are bicoloured yellow and has a body length of about 3 mm.

The bedeguar gall is surrounded by a dense mass of sticky branched filaments. This structure gives the appearance of a ball of moss, and its filaments are often brightly coloured, being at their best around September; starting off green and then passing through pink and crimson to reddish-brown.

A large specimen can be up to 10 cm in width. The larvae develop and then over winter as pupae in the now brown and dry-looking structure, emerging in May. The unilarval chambers are set in a woody core which persists after the filaments have worn off.

The bedeguar may also develop on ''Rosa rubiginosa'', ''R. dumalis'', or ''R. rubrifolia''.

The gall induced by ''D. mayri'' differs in being more sparsely covered in short, unbranched filaments and the galls usually develop on the twigs.

Behavior

''Diplolepis'' females lay up to 60 eggs within each leaf bud using their ovipositors. The asexual wasp emerges in spring; less than 1% are males. A similar gall is caused by ''Diplolepis mayri'', but this is much less common.

Predators

Mature galls are sometimes broken open by vertebrate predators to recover the larvae or pupae. The large size of the emergence holes of the individual cells sometimes suggests predation by birds or small mammals has taken place.

The bedeguar is a good example of a complex community of insects. 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.

The gall-wasp ''Periclistus brandtii'' causes no gall itself, but deposits its eggs in the bedeguar tissues on which the larvae feed. In turn, these larvae may be parasitised by a chalcid wasp, ''Eurytoma rosae'', which works its way from one inquiline's cell to the next.

The parasitoid ichneumon ''Orthopelma mediator'' lays its eggs directly into larvae of ''D. rosae'', killing them. The chalcid wasps ''Eurytoma rosae'' and ''Glyphomerus stigma'' can attack both the larvae of ''D. rosae'' and of the inquiline ''P. brandtii''. These parasitoids may in turn be attacked by hyperparasitoids such as the chalcids ''Caenacis inflexa'' and ''Pteromalus bedeguaris''.

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

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.

Uses

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