'It's carnage and mayhem in your garden,' says Erica. The bee-fly needs to lay her eggs quickly as she is competing with other flies and wasps that are also trying to parasite the solitary bees. She is essentially carpet-bombing her eggs, which she has to do while the bee is away from its nest.' 'This helps her do something called bombing, where she fires off a row of eggs. The dark-edged bee-fly's ovipositor (egg-laying tube) has a spine that allows her to flick her eggs, adds Erica.
'She then flies over to the solitary bee's nest and flicks out the eggs, hoping they will hatch near or in the nest.' The sand protects and camouflages the eggs while also giving them extra weight. 'First the female moves her abdomen in a twerking motion to scoop up sand and gravel to coat the eggs. Many bee-fly species are parasites of bees and wasps, but there are some that target beetles, grasshoppers, ants, moths or caterpillars.ĭr Erica McAlister, Senior Curator of Diptera at the Museum, explains how a dark-edged bee-fly lays her eggs in a solitary bee's nest and the unfortunate fate of the bee larvae when her eggs hatch: The larva is a parasitoid, meaning it is a parasite that will end up killing its host. While adult bee-flies are adorable, a young bee-fly isn't quite as endearing. These black and white beauties are likely highly beneficial mason wasps looking for an empty apartment in which to raise their brood.The gruesome parasitic nature of a young bee-fly So, when you see these magnificent black and white wasps hovering around mason bee colonies, fear not, your mason bees are not under attack. Due to the shorter developmental time of the male offspring, male eggs are usually placed near the opening of the gallery and female eggs are placed deeper within. In a remarkable display of gender control the female wasp is able to lay either a male or a female egg. Once a sufficient number of prey have been captured, the chamber is sealed with a plug of mud or sand particles. Sometimes as many as 19 caterpillars are captured, paralyzed, and used to provision the cell where an egg awaits. Like potter wasps we met in a previous episode of Bug of the Week, female mason wasps use a potent venom to paralyze their pray. She then hunts for prey on flowers and foliage. Prior to the hunt for caterpillar prey, the female mason wasp deposits her egg in the chamber where caterpillars will be stored. Unlike the larvae of mason bees that consume pollen cakes supplied by their mothers, many mason wasps consume living but paralyzed caterpillars. As adults, mason wasps provide the important ecosystem service of pollination as they seek nectar and pollen as food sources. The hollow chambers excavated by larvae of wood-boring bees like carpenter bees, and beetles like round headed borers are used by several species of mason wasps as homes to raise their brood. However, mason bees are not the only members of the bee and wasp clan that evolved to take advantage of vacant galleries in wood.
#Black bee with white spots full#
You may recall photographs of logs drilled full of holes to accommodate industrious mason bees in my mason bee colony. Were these another type of deviant ruffian out to eat mason bee babies and pillage their pollen cakes? She wondered about their identity and intent. Last week an eagle-eyed Master Gardener made an inquiry regarding black and white wasps poking around her mason bee colony. Several years ago we also met dastardly parasitic leucospid wasps that raid mason bee nests and kill bee larvae within their galleries.
In previous episodes of Bug of the Week we enjoyed learning about mason bees, important early season pollinators of many native plants.
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