Daffodils and the Narcissus Fly

I have a problem with daffodils, Narcissus species and varieties.  The problem is this, Merodon equestris, the narcissus fly:

I carefully buy and plant daffodils in good soil in autumn and next season they come up beautifully, delighting Maria.  The following year they're sparse, with few flowers.  By season 3 they're gone.  And the culprit is on the wing again.

Despite appearences they're hoverflies, not bees, though they mimic bees as protection against predators. And it's not the adults that are the problem but the larvae.  Eggs are laid at the base of the plants, they hatch, and the white larvae burrow down to the bulbs where they proceed to eat out the hearts, including the newly forming flower buds for next year.  The result is that the bulbs come blind in the next season and then dwindle.  

It's not just daffs they go for.  Other bulbs in the Amaryllis family, including snowdrops, Galanthus, can also be affected.  In fact I've given up trying to grow them except as disposable seasonal displays.  I'd love to build a collection of the smaller Narcissus and a population of snowdrops but it's just money wasted.  I use no pesticides in the garden so I've got no means of control other than natural predators - and, if they're around, they're not doing a good job.  I'll have to dock their wages!

On Narcissus and the Narcissus fly

Out in the garden doing a bit of photography this afternoon (in between rain showers) I came across a very cooperative hoverfly, Merodon equestris.

Merodon equestris

It's a bumble bee mimic, about the same size, and relying on its similarity in markings to avoid predators.  It has no sting.

Except for gardeners.

Normally I'd write this up on my photography blog but this is the narcissus fly.  They emerge about this time of year having spent the preceding summer and winter as larvae nestled in the heart of Narcissus bulbs.  Females will get together with males and then lay their newly fertilised eggs on the decaying stalks and in the holes left by the decaying stalks of the spring flowering members of narcissus and lily families.  The larvae then burrow down and into the bulbs, eating them out over the course of the next few months.  They may not kill them - but they do come blind.

It's not a serious pest for gardeners.  But it is a pest.  And I've got it in my garden.  Which may explain why I add narcissus varieties on a yearly basis but they simply don't establish.

Having said that it's only one explanation for rather more failure than I'd like.  I was looking forward to a good display of the May flowering Narcissus poeticus this year, having invested in a number of the comparatively expensive bulbs last year to fill a noticeable gap between spring and summer flowers.  Ambrosia, exclaimed my slugs, and gnawed them off at ground level as soon as they emerged.  For this year I'll just have to be content with photos:

Narcissus poeticus

Narcissus poeticus