A pretty pest

Looking for bees in the garden the other day, I came across an insect that looked a lot like a honeybee or small bumblebee, but something was not quite right.

Narcissus bulb fly on chive flowers

Right color, right hairy abdomen and thorax, expanded upper segment of rear legs where pollen baskets are located — but is this a bee?

It’s the eyes — they’re too large and round, and the antennae are too short.  It must be a bee mimic fly.

Honeybee, NPR science news, June 7 2018, photo by don Farrall/Getty images,

A honeybee, for comparison, has a triangular rather than round head, and ovoid eyes.  Photo from an article on NPR science news, June 7, 2018, by Don Farrall, Getty images.

I think my bee mimicking fly is a Narcissus bulb fly, and if so, my iris, lillies, and chives are in trouble. Adults feed on the nectar and pollen of a wide variety of flowers.

Narcissus bulb fly on chive flowers

A male Narcissus bulb fly dips its proboscis deep into the chive flowers. The two eyes touch at the center of the head of the male, but are separated by a small space in females.

But their larvae infest the soft tissues of the bulbs of these perennials.  Females lay from 40 to 100 eggs at the base of a leaf of bulb-forming plants, and the larvae crawl down into the soil and burrow into the bulb, eventually hollowing it out completely as they feed and mature to pupal stage.  Lillies, iris, daffodils, tulips, hyacinths, etc, are all susceptible to infestation.

Narcissus bulb fly on chive flowers

There doesn’t seem to be a good way to control these pests, introduced from Europe, probably along with bulbs, in the late 1800s. Their strong bee mimicry makes most insect predators leave them alone.  Apparently, if you grow bulb-bearing plants in your garden, you’re very likely to have these destructive pests present.

6 thoughts on “A pretty pest

    • Right! Well, at least they are less numerous (so far) than the dreaded Japanese beetle which will emerge in a couple of weeks to decimate my roses and raspberries. Double ugh!!

  1. Oh wow! that sounds awful.
    The yucca moths that pollinate yuccas eat all the seed too, but they are the only pollinators for yuccas. There is a distinct species of moth for each species of yucca. They wad up the pollen and literally stick it onto the pistil of the flower into which they deposit their eggs. Their larvae then have something to eat as the seed develop. Flowers that do not get pollinated by the moth make no seed. Flowers that get pollinated make plenty of seed, but almost all of it gets eaten by moth larvae.

    • That’s an interesting relationship. Enough seed must escape getting eaten to make this system a viable one for reproduction though. Tony, the article I read mentioned California as one of the hot spots for this Narcissus bulb fly. You might see them hovering around or sampling nectar from your flowers.

      • I have heard about them, but that is about it. I would not have recognized one if I saw it. I have never heard of them being a problem. Bulb crops no longer grow around here. There are cut flower crops on the coast, and bulb production on the very northern coast, but that is about it.

      • The yuccas and their moths really seem to know what they are doing because yucca do quite well in the wild. Most grow from roots. Seedlings are very rare among out native yuccas at least.

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