Physical Appearance

Trachusa species typically have dark abdomens, often interrupted with prominent bands of white or yellow. The head and thorax can be covered with fairly long pale hair.

 

The eyes of certain Trachusa species are very striking, being either pale blue or lime green.

 

Like all members of the family Megachilidae (which include Megachile – leaf-cutter bees, Osmia – mason bees and Anthidium – carder bees), the female carries pollen in a brush of specialized hairs, called a scopa, on the underside of her abdomen.

 

Characteristics

There is no recognized common name for the genus; however, one species, Trachusa perdita, is sometimes referred to as the “California leafcutting bee”.

 

The males of Trachusa species are very territorial, a characteristic of bee genera belonging to the tribe, Anthidiiini. The male Trachusa will claim and patrol a particular sector of forage plants, protecting this resource for females of their species. If intruders of another bee species land on a flower in their territory, they will drive the intruder off with darting and ramming maneuvers. In southern California, Trachusa bequaerti males are even known to intimidate Centris, a much larger bee, from foraging on common floral resources.

 

Trachusa species typically have long tongues which allow them to extract nectar from deep tubular flowers.

 

Trachusa species will collect pollen from a range of plants, with Psorothamnus spinosus (smoketree), Larrea (creosote bush) and Prosopis (mesquite), being particularly important desert forage plants in California and the Southwest. In fact, one species of Trachusa, Trachusa larreae, is named for an associated host plant: Larrea – creosote bush.

 

Size: Medium sized bee, approximately 1/2 inch in length.