narcissus bulb fly

LC - Least Concern

NNA - Not applicable

not listed

Narcissus bulb fly is a large, exotic, hover fly. It strongly resembles a small bumble bee. It is native to Europe. It has been introduced into Great Britain, Japan, New Zealand, and North America. It spreads when bulbs from Europe are shipped worldwide. In North America it is adventive, not naturalized – its numbers cannot be sustained without periodic population boosts from Europe. In the United States it occurs in the east from Maine to Georgia, west to Minnesota and Illinois, and west of the Rocky Mountains from Washington to central California. Between these regions it also occurs in the areas surrounding the largest cities. Larvae feed on the bulbs of Narcissus and other plants in the Lily (Liliaceae) family. They are considered serious pests of daffodils. Adults fly low to the ground among vegetation and are seldom seen. They feed on pollen and nectar of a wide variety of flowers.

Adults are robust, hairy, and ½″ to ⅝″ (12.3 to 17.2 mm) in length. Several subspecies have been described on the basis of the color of the hairs on various parts of the body. These are now treated as color morphs of a single variable species.

The head is hemispherical, not flattened. There are two large compound eyes on the sides of the head and three small simple eyes (ocelli) in a triangle on the top of the head (vertex). The compound eyes are covered with short erect hairs. On the male they are narrowed abruptly and meet at the top of the face (frons). They do not meet on the vertex in either sex. The difference is visible when viewed from the front but not from the rear. The face is mostly covered with hairs. The antennae are short and black. They have three segments. At the base of the third segment (flagellum) there is a long, forward-pointing bristle (arista) on the upper side.

The thorax and abdomen are densely covered with erect yellow, orange, and black hairs. On one morph the hairs are entirely yellow. One morph has a broad, sharply defined, black band at the rear of the thorax extending onto the front of the abdomen. More commonly, the thorax and abdomen have orange, yellow, and black hairs, but the extent of the black and orange hairs is highly variable. The intensity of the orange hairs is also variable, from dark burnt orange to bright orange to orangish-yellow.

At the tip of the wing the end of the M₁ vein curves inward toward the wing base, creating a cell that is said to resemble a sock.

The legs are entirely black. On the hind legs of the male there are two spurs at the tip of the fourth leg segment (tibia).

½″ to ⅝″ (12.3 to 17.2 mm)

Narcissus and other plants in the Lily (Liliaceae) family

Mid-March to late July

Adults fly low to the ground

Maggots overwinter

Pollen and nectar of a wide variety of flowers

Sources

24, 29, 30, 82, 83.

Locally common

Merodon equestris narcissus bulb fly

Merodon equestris narcissus bulb fly male Barnes Prairie, Racine Co., WI June 10 2021

Location: Barnes Prairie, Racine Co., WI

Merodon equestris narcissus bulb fly male Barnes Prairie, Racine Co., WI June 10 2021

Location: Woodbury, MN