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?

the Narcissus Bulb Fly

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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