of habitats. An estimated 10 species of Hylaeus may already be extinct in the Hawaiian Islands. Hylaeus hirsutulus from Kaua‘i; H. angustulus from Maui Nui; H. kukui from Maui and Hawai‘i; H. crabronoides, H. filicum, H. muranus (= insignis), and H. rugulosus from Hawai‘i; and H. specularis from Hawai‘i, Moloka‘i, O‘ahu, and Kaua‘i (and presumedly Maui) all have only been collected and recorded in low numbers. These populations may potentially be under threat, however also exist in relatively large areas, and so may exist in larger populations than currently known. These species require further investigation to conclusively determine their status. In the past 30 years, only three specimens of Hylaeus facilis have been collected from the Hawaiian Islands - one from O‘ahu in 1975, one from Maui in 1993, and one from Moloka‘i in 2005. Previous to 1930, this species had been described as widespread and abundant. It remains uncertain why these populations have decreased significantly while substantial habitat remains and closely related species remain abundant. Hawaiian species H. anthracinus is known to be affected by the presence of invasive ant species, decreasing both nest success and the number of adults produced per successful nest. The black household ant (Ochetellus glaber) has been observed depredating nests, removing pollen, eggs, larvae and pupae. The African big-headed ant (Pheidole megacephala) can co-exist with H. anthracinus at low densities, however excludes them from ground-nesting opportunities when populations rise. In contrast, the yellow crazy ant (Anoplolepis gracilipes) is known to expand rapidly and remove this species from its range. In Australia, the presence of commercial honey bees has been found to reduce the fecundity of the endemic Hylaeus alcyoneus, with 23% less nests being made when honey bees were present. Selected species Species of Hylaeus include: Hylaeus agilis Hylaeus alcyoneus - Banksia bee Hylaeus anthracinus – anthricinan yellow-faced bee Hylaeus assimulans – assimulans yellow-faced bee Hylaeus facilis – easy yellow-faced bee Hylaeus globuliferus Hylaeus hilaris – hilaris yellow-faced bee Hylaeus krombeini Hylaeus kuakea Hylaeus longiceps - longhead yellow-faced bee Hylaeus mana Hylaeus nigritus Hylaeus punctatus Hylaeus sanguinipictus Hylaeus sedens Hylaeus signatus See also List of Hylaeus species References External links Worldwide Hylaeus species Distribution Map List of Hylaeus Species Female Hylaeus Identification Guide Male Hylaeus Identification Guide Bee genera Colletidae