''Merodon equestris'' (Narcissus bulb fly, greater bulb fly, large bulb fly, large Narcissus fly) is a

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical regi ...

species of

hoverfly Hover flies, also called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while ...

(Family Syrphidae). Like many other hoverflies it displays a colouration pattern similar to a stinging insect (a

bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gene ...

in this case) as an

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

ary

defense mechanism In psychoanalytic theory, a defence mechanism (American English: defense mechanism), is an unconscious psychological operation that functions to protect a person from anxiety-producing thoughts and feelings related to internal conflicts and o ...

. Other syrphid bee mimics are '' Mallota'', '' Arctophila'', '' Criorhina'', '' Pocota'' and '' Brachypalpus''. ''Merodon'' species are distinguished from these by the very strong hind femora, which bear a large triangular projection on the underside near the tip. It flies in low vegetation while the other bumblebee mimics prefer higher vegetation layers.

Description

A stout fly with a small head. The tergites are black, without the dust spots or blue-purple sheen of other ''Merodon'' species. The thorax and abdomen are hidden by dense, long, erect hairs of variable colouration. Tibia 3 of the male has 2 spurs at the apex. The larva is described and figured by Hodson (1932) and it is illustrated in colour by Rotheray (1993).

Distribution

In the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Si ...

it is found from Fennoscandia south to Iberia and the Mediterranean basin, and Ireland east through Europe into Russia and Japan. In the

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America ...

it is found from British Columbia south to California. It has been introduced to New Zealand.

Biology

Habitat: Open areas in deciduous forest up into the subalpine zone but significantly synanthropic, occurring in suburban parks and gardens and on horticultural land. The adult flies low in April to July with a fast zig-zag flight, among ground vegetation frequently settling on bare ground. Adult ''M. equestris'' feed on

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

and nectar. They visit a large variety of flowers for nectar, while the larvae feed internally in tissues of bulbs of

Amaryllidaceae The Amaryllidaceae are a family of herbaceous, mainly perennial and bulbous (rarely rhizomatous) flowering plants in the monocot order Asparagales. The family takes its name from the genus '' Amaryllis'' and is commonly known as the amaryl ...

, and they are regarded as a horticultural pest, especially of '' Narcissus''. A bibliography of the literature on the biology of ''M.equestris'' is given by Barkemeyer (1994)Barkemeyer, W. (1994) Untersuchung zum Vorkommen der Schwebfliegen in Niedersachsen und Bremen (Diptera: Syrphidae). ''Naturschutz und Landschaftspflege in Niedersachsen'', 31: 1-514.

Colour forms

File:Merodon (female).jpg, var. equestris (female) File:Merodon equestris (male).jpg, var. narcissi (male) File:Merodon equestris01.jpg, var. validus (female)

References

External links

{{DEFAULTSORT:Merodon Equestris Eumerini Diptera of Asia Diptera of Europe Diptera of North America Insects described in 1794 Taxa named by Johan Christian Fabricius