Lithurgus bees are commonly named wood-boring bees because of their specific nesting behavior. These species dig holes in dead wood to make their nest. They are robust and large-sized bees (10-12 mm in length on average and up to 19 mm), commonly with hair bands on the abdomen. There are 33 species worldwide, including 3 species already known in Morocco. We describe here the first observation of the wood-boring bee Lithurgus tibialis in Morocco.
Wood-boring bees are solitary. They are observed flying from June to August and have only one generation per year. Their latin name Lithurgus (Lith- = stone, urgus = worker) suggests that they are nesting in stones however it is not the case at all. These bees dig their nest in soft rotten wood and partition the cells using sawdust or fine wood chips chewed from the sidewalls of the burrow. Subsequent generations never reuse these burrows, however these cavities are often utilized by other bees such as mason bees (Osmia and Hoplitis) or leaf-cutter bees (Megachile). They are mostly encountered in tropical and warm temperate regions. Most European species have a strong preference for thistles (Carduus, Centaurea, Cirsium, Onopordon).
In July and August 2018, we recorded the wood-boring bee Lithurgus tibialis for the first time in Morocco, in the middle Atlas (Sefrou province). Three specimens were collected, 2 females from pan traps placed in a Control zucchini field (farmer: Lahcen Azai) and in a FAP pumpkin field (farmer: Kharbach Abdellah), and a male sampled while foraging on zucchini flowers in a FAP field (farmer: Abdellatif Khariji). The natural history of Lithurgus tibialis is not well known. It is smaller (8-10 mm) than most other wood-boring bees and looks quite different from other wood-boring bees occurring in Europe. Males are characterized by thickened femur of posterior legs and arched tibia (probably explaining the origin of its name) and females have a poorly developed frontal ridge (probably used to excavate their nest). Following an Arabic binomial nomenclature (Boustani et al. in prep) we propose to name this species Mouhaddabat al Jabin Mokawwassat Al Kassba (محدبة الجبين مقوسة القصبة). Mouhaddabat al Jabin (= humpy forehead bee) corresponds to the genus name and Mokawwassat Al Kassba (= with arched tibia) corresponds to the species name. This species has a peculiar preference for flowers of undershrubs (Chrozophora), an unusual pollen source for wood-boring bees. However, it has also been observed visiting almond and cherry orchards in highland Jordan and camelthorns (Alhagi) in Iran. The males can also be found on flowering mint. This bee species has a pretty wide distribution ranging from Portugal to south-eastern Pakistan and was only known from Egypt in North Africa (see map on Discover life).
If you want to know more about the taxonomy and ecology of wood-boring bees, read the revision of Zanden (1986). There is no specific literature on the wood-boring bees of Morocco, but books on the Megachild bees of Europe or, more recently on the bees of Europe can help with species identification.
I would like to thank Andreas Müller (ETH Zurich, Switzerland) who identified the specimen. This research was funded by the Federal German Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) through the International Climate Initiative (IKI).