The larva lives in a gallery beneath the bark of different Tamarix species. The gallery is often made horizontally in the bark. Yellow frass is ejected out of a tiny hole but it doesn't always remain visible.

The larva hibernates only once. Before pupation it constructs a tight cocoon at the end of the gallery, with a thin piece of bark remaining to cover the exit hole until emergence.

Due to the extended flight period, larvae can be found all year round in different stages of development .

After emergence (mostly between 10:30 and 13:30) females start to lure immediately. Around noon, freshly emerged adults can be found resting on the trunks of the host plant. After mating, which lasts less than one hour, the eggs are laid in crevices and grooves in the bark of trunks and branches of the host plant. Rather big trees and shrubs are preferred.

Males are attracted by the Pherobank pheromone lure intended for Bembecia ichneumoniformis.

Larvae are found in the bark of different Tamarix species (Tamarix gallica, T. tetrandra, T. africana, T. boveana).

Synanthedon theryi occurs in many different localities, as long as suitable host plants are present.