Biology of megachilid bees from Dagestan A female of Megachile albocristata Smith, 1853 at her nest entrance B same nest sealed with pebbles C nest cell of Megachile flavipes Spinola, 1838 extracted from the substrate D female of Hoplitis mocsaryi (Friese, 1895) at her nest entrance E same nest entrance from above F dissected old nest cell of Sceliphron sp. with a cell of Osmia cornuta (Latreille, 1805) containing a cocoon G female of Hoplitis astragali Fateryga, Müller & Proshchalykin, 2023 closing her nest with a plug of mud H nest of Hoplitis curvipes (Morawitz, 1871) extracted from the substrate I male of H. curvipes sleeping in an inflorescence of Allium rotundum L. s. l.