An anchoring device for insertion in a hole provided in a structure such as a wall (hollow or solid) comprises proximal and distal sections. The proximal section includes a head defining an aperture for receiving a fastener, and the distal section includes a pair of expandable wings displaceable between collapsed and expanded positions. Each wing is biased towards its expanded position such that the wings can engage the structural material delimiting the hole or a distal surface of the structure. The distal section comprises, proximally of the wings, a variable-length flexible portion for allowing the wings to engage the distal surface of the structure for various structure thicknesses. The distal section comprises, distally of the wings, a tip section adapted to spread outwardly when engaged by the fastener. The proximal section comprises a pair of legs each having a toothed rack for engaging the structural material.