Wednesday, June 14, 2017

The Last Daffodil and What Eats It

This week temperatures have skyrocketed, but until recently it's been quite a cool (and sometimes downright chilly!) spring.  The last daffodil in my collection to bloom this year, Narcissus 'Actaea', flowered for over three weeks from mid-May through the end of last week.

Narcissus 'Actaea' - last daffodil bloom this year
The winding down of daffodil season, however, is when the fight to save my daffodils steps up.   In May and early June is when the critters that eat them come out to play.  And just what eats daffodils, the bulb that is impervious to almost every other garden pest around, you might wonder?



Frank from the garden blog Sorta Like Suburbia first told me about this fly, whose larvae burrows into the bulb and eats the middle of it, weakening or killing the plant.  After a quick google search, I knew I had seen this fly in my garden.  (Thank you, Frank!)  It's a good-sized fly whose various colorations mimic bumblebees, and when it flies it makes a distinctive whining sound.

Narcissus Bulb Fly
The adult flies emerge in late spring/early summer and live for 2 to 3 weeks.  I often see them around my flowers on sunny days this time of year, feeding on nectar and pollen.


After mating, the female flies lay anywhere from 40 to 100 eggs each at the base of suitable plants, one to three eggs per plant.  That's a lot of infested plants!  They usually lay eggs on daffodils, but they will also infest snowdrops, hyacinth, iris, lilies, amaryllis, and tulips, among others.

Narcissus Bulb Fly laying egg at base of daffodil leaves
After a few days the eggs will hatch and a larvae will wriggle down the outside of each bulb to feed on the basal plate that is on the bottom of the bulb.  It then bores into the middle of the bulb to feed on it, hollowing out the middle of the bulb as it grows larger and larger.  The larvae overwinters inside the bulb, and in early spring it pupates for a month or two (either inside the bulb or in nearby topsoil), finally emerging as an adult fly.


Of course, this usually spells disaster for the plant.  Sometimes the larvae's damage won't totally kill the bulb, and it will be able to send out small leaves and slowly recover over the next two or three years.  Unfortunately oftentimes the bulb is destroyed beyond recovery.


Thus I have been busy fighting these pests for the last weeks.  The Narcissus Bulb Fly is a tough fly to control.  Some people have luck using systemic insecticides, however I try to garden as organically as possible.  Daffodil growers often use hot water bath treatments to kill larvae from Bulb Flies and other pests.  To do this, after the leaves have died back, dig up bulbs that might be infested and submerge them in hot water that is 109° to 111° F (42°-44° C) for one hour.  The heat will kill the larvae; just make sure to avoid higher temperatures that cook the bulb!


I go for a slightly less complicated route - I become a Fly Hunter for the few weeks that they are out in the garden.  I am out gardening quite a bit this time of year, so I garden with a butterfly net handy.  I listen out for the familiar whine when gardening and often check the flowers that they particularly frequent.   When I see a Narcissus Bulb Fly, I swoop the net on top of it.  The fly usually flies straight up to the top of the net, so I then carefully gather the material around the fly and bring it somewhere I can stomp on and kill it.  So far this year I've killed about two dozen flies.


Here's hoping that it's enough to save most of my daffodils.


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25 comments:

  1. Yikes! Ignorance is bliss! I had no idea these nasty buggers exist. I wonder how often I've seen them and thought they were bees.....My Irises didn't bloom well this year. Makes me wonder if they are fighting this fly. Thank you for the info....ps....it's nice to get some cooler summer weather!

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    1. Yeah, it makes me wonder about a few of my plants that didn't do so well too. It very well could be fly damage.

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  2. Sad to see daffodil season end but how exciting to experience the joys of summer. I hope your control method works well as I can't imagine digging up all your daffodil bulbs to give them a bath. I'd no idea that this pest existed.

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    1. P.S. Where in Alaska did you grow up? I was raised in Southeast and continued working there in the summer for a number of years after college.

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    2. I think only people who have a large, valuable collection of bulbs do the water bath because it does seem like quite the chore. I lived near Fairbanks for several years as a kid. Quite a ways away!

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  3. It's a pity that such a cute looking insect can cause so much damage.

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    1. Most flies that mimic bees are beneficial - this one not so much!

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  4. Interesting! Another exotic pest -- although in this case, it seems like it's mostly attacking exotic plants? (Small comfort, I guess...)

    I don't think I've seen this critter around my garden at all. The daffodils seem to persist and multiply year after year. Maybe the larvae can't tunnel through my solid clay soil?

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    1. Hopefully you don't have them! I don't remember seeing them in North Carolina, either. That clay soil has to be good for something, right?

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  5. Good luck with your hunt! You sound rather ferocious. What a noxious pest, and to have the effrontery to pose as the helpful bumblebee - disgraceful!

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    1. I know, trying to trick us into thinking it is a helpful insect! Very devious of it!

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  6. This is a new insect to me. I don't think I've ever seen one in our garden. Does the bulb have holes in it? I'm curious if the fly is native or introduced. And does it attack native bulbs or just the exotic ones? Good luck with your quest.

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    1. Thanks! The fly is introduced from Europe, and it attacks plants in the Amaryllidaceae family, of which we only have a few native ones in that family over here. The bulb ends up having a small hole in the bottom and looking like the middle has rotted out.

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  7. I need to do more research on this fly since they attack amaryllis, too.

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    1. I hope you don't have them down there!

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  8. Wow, I thought nothing bothered daffodils! Your method of control sounds better than digging up all those bulbs--what a task! I do something similar when the Japanese beetles arrive, trying to catch them napping and then drown them. We've had a much warmer spring than you, apparently; in fact, it's been miserably hot here lately, and my daffodils are long gone.

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    1. That's what I thought too! One of the reasons I grow so many daffodils is that they critters don't bother them. Too good to be true, right? I hand pick Japanese beetles when they come out, too. Always something! I hope it cools down for you.

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  9. Very interesting as I am not sure I have ever seen this fly....red lily beetles and others who bring problems but not this one yet. Hope your daffs survive.

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    1. I hope you don't get it. Too many bugs to fight in the garden!

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  10. Hello dear Indie !!

    As always great relationship and beautiful pictures.
    Thank you that i could see your garden and the plants.

    Kisses and greetings.

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  11. I was unfamiliar with this fly. Thanks for the information.I can see you out there swooping down on one! I hope your fly-catching skills make a difference..

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  12. Oh, for pete's sake, daffodil-eating bumblebee impersonators? I've never heard of these bugs, but of course, something has to come along and destroy even the daffodils. I like your method of control, it would give me great pleasure to destroy the menace, too. :-)

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    1. It's always got to be something, doesn't it? Thankfully it has a pretty distinctive sound so you can tell it apart from a bumblebee.

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