The Bombylius major L. 1758 species is in our entomological review since 2013. This bee-fly was observedon differentblossom plants like: Taraxacum officinale, Lamium album, Urticadioica, Trifolium repens, Melilotus albus, M. officinalis, Medicago sativa, Hypericum perforatum, Tilia platyphyllos, T. tomentosa, T. cordata, Rosehips, Malus domestica, Pirus sativa, Prunus domestica from the campus of the State Agrarian University of Moldova (SAUM) and Didactic Experimental Station „Chetrosu” (DES). Thanks to high population density and interesting morphological appearance that imitate a bees, this insect astonished us in professional plan and we started to studied her biology and ecology in condition of our country. The relevant information regarding the bio-ecology of B. majoris L. 1758 presented below in this work. At first look, the adult appears as a bumblebee or bee; this is due of her large body – about 14 to 18 mm in length and up to 24 mm of wingspan. The body is robust, bulging, covered with short hairs dense coloured predominantly in brownish to yellow. The antennae are short and being as arista type. The chest tergits are black and shiny, but covered with a yellow, brown or white pubescence. The wings have appearance of „semi-rigid wing”, because of darker upper edge and waves outline. Spindly legs are well developed, especially the first pair with which the insect accost the flowers for to introduce their trunk for to extract the nectar. The proboscis is black, long approximately body length and sharpened at the tip. Initially insect can cause discomfort: 1) visual – the trunk, the first pair of legs and efficient flight, including the possibility to stay suspended in the air, to swing and jumping; 2) auditory – awful buzzing, due to premotor fly apparat and very effective. At appearance of a threat, B. major L. 1758 fly instantly from flower, being very carefully. Imitating bees, the Large bee-fly approach to the victim nest because at sexual maturity the fly deposited egg in/or near underground nest of bees and wild solitary wasps. In case that the fly cannot to approach to the nest, then the female lay eggs on flowers, which are visited by pollinating insects. The adult is a perfect pollinator, carrying the shaken and deposited pollen on the brush body, but in the larval stage this fly is a parasitoid of other pollinating insects and with this affect their populations. Larvae are hyper-parasite. After hatching from egg that have a grain of rice size and humidified for to be “wrapped” in sand, the larvae cross the path to the nester catching to the host’s body penetrate inside it. For the first, the larvae have three pairs of false legs in sucker appearance, owing to this it moves quickly and feed with remainders from the wasps nest, being detritophages. During of development the larvae moults, and in the same time the legs atrophied, adhering to the body of the larva-host and become an ectoparasite. In addition, these larvae may can parasite the beetles, butterflies (especially owlet moths), bees and wasps (solitary and wild, especially from the genus Andrena) larvae. At full development, the larvae remain to hibernate like pupa into the hosts nests. Figure 1. The Bombylius major L. 1758 species – registered in Moldova during of 2013-2016 (orig.) In native literature, some authors mention this species: the Negrobov (1983) which represented general information about the spread of this fly – South of Europe; and some morphological aspects (Cozari 2010). From synonyms of this insect species, we find thehistory of research of this. The earliest dates that describe it and gave scientific name – Bombylius major 1758 was Swedish Linnaeus. The next were his country as Sulzer (1761) and De Geer (1776). Then following scientists Fabricius (1781), the Frenchs Geoffroy (1785) and Macquarts (1840), the Germans Wiedemann (1828) and Loew (1855). On the American continent, Lioy studied this species (1864). Among those entomologists, only Frenchman Geoffroy put these fly in another genus – Asilus and species lanigerus. As can be seen all researchers have accepted genus name – Bombylius, only that species were different. During the years for this species has been given10 scientific names. In conclusion, the species B. majorduring of 2013-2016 was observed in abundance on diverse herbaceous vegetation and woody flower from the SAUM campus and EDS „Chetrosu”. The first adults were registered in April (2014) and (2013, 2016), but this year and in late July were observed specimens on honey clover – Melilotus albus. The hot conditions of weather in July of 2016 – above 30oC did not stop flying and has been seen on almost dried flowers.