In fear of the Narcissus Fly

[uvularia]

I have to say that starting a collection of Galanthus is very exciting but after reading much about their cultivation, one starts to live in fear of the Narcissus Fly. Luckily my only losses to this creature is 'Brenda Troyle' and she is proving to be relatively vigorous. So not a disaster. But I would be upset if my less vigorous varieties were attacked. Apart from constructing a 'Narcissus Fly-proof' bulb house, can anyone suggest some simple ways of protecting individual clumps?

[Alan_b]

Systemic insecticide.

In principle you could construct covers for use when the flies are active.  Last year I covered a whole raised bed and a collection of pots with fleece from late May to late August.  Nothing has obviously suffered but it's way too soon to know if I have derived any benefit.  My concern was the Swift Moth, because their larvae have a voracious appetite for snowdrops.

[Maggi Young]

Kentish Lass has told us before of using upturned hanging baskets covered with  fine mesh or horticultural fleece to protect individual clumps.
As you might imagine, narcissus fly  features quite often in forum discussions - mostly with assorted expletives!

[Maggi Young]

Some of the threads showing  the worry of this pest!

http://www.srgc.net/forum/index.php?topic=204.0

http://www.srgc.net/forum/index.php?topic=3690.0

http://www.srgc.net/forum/index.php?topic=9919.0
http://www.srgc.org.uk/smf/index.php?topic=4405.0

http://www.srgc.org.uk/smf/index.php?topic=4297.0    lesser narcissus fly

http://www.srgc.org.uk/smf/index.php?topic=1850.0

[uvularia]

Thanks Maggi! That is a few threads to have a look through!

[Maggi Young]

Don't do it all at once, Paul - you'll depress yourself.   Though reading of Martin Baxendale patrolling his garden with a tennis racquet to swat 'em is quite amusing!

So many references in the forum - amazing what the little blighters can chomp their way through. 

Alan B. and others also speak of the danger from Swift Moth caterpillars -  let's face it - sometimes it seems there are armies of munching enemies  in the garden, just waiting to ruin our day.

[GordonT]

Sorry - I oughtn't to have posted this under Galanthus... it is just that bulb flies managed to ruin a large part of our future garden plans. Last year we gave up entirely on growing any Narcissi in our gardens. We bought a lot of Narcissus 'Ice Follies' in the autumn of 2012, and they made an impressive show in May last year. During garden expansion after the foliage had died down, I realised that I had to regroup the Narcissi. Every one of the bulbs was fly blown! The blighters didn't spare a single one. I checked all of our other plantings and all bulbs had been ruined.

I'll take my chances with Tulips and White Tailed Deer rather than attempting Narcissi again!

[mark smyth]

Thankfully last year until July was too cool  for them to be active. Fly swats! I keep about four in the garden and one in the back pocket. Hit them hard! They like to bask on stones and large leaves. Every one I kill I give it a squeeze. If an ovipositor pops out I'm very happy.

Systemic pesticides all the way

and learn how to tell them from the good guys

[Alan_b]

Narcissus flies come in from the top of the bulb and the entry wound should be obvious if you lift and divide your bulbs when dormant.  If you cut-open the bulb (or the remaining husk) then the fly larva should still be inside.  Therefore an effort-intensive way of dealing with the flies is to lift your bulbs when dormant and check for entry wounds.  This is easiest if you plant your snowdrops in lattice pots.  Obviously this doesn't much help the bulbs but reduces the numbers in the next generation of flies.

Swift moth larvae attack from the side or the base and I think they will also eat the large roots during the growing season.  They sometimes eat only some of the bulb and move-on so some bulbs survive an attack and eventually recover.  I suspect that they are particularly attracted to snowdrops as I have lost snowdrops from amongst other bulbs.  I don't know whether they emerge from the soil at all until they pupate so I am trialling lattice pots as a means of restricting their movements, as all the well-fed larvae I find are too large to fit through the holes in a lattice pot.  The moths are supposedly active from June to August and they lay eggs on the wing therefore any protective covering would need a very fine mesh to prevent the eggs dropping through.  I also treat my soil with Nemasys 'Grow your own Nematodes', being the best hope I can find of achieving a biological control.

Edit: Good note on Swift Moths here: http://www.donsgarden.co.uk/pests/538?telephone=5     

[uvularia]

Thanks folks! Excellent info! Sounds like I need to stock up on Systemic Pesticide? Is there a particular one that works well?

I did read that Galanthus grown in permanent shade were less likely to get attacked? So I have gone for a north wall. Not the best place to show them off?
Does anyone think this works? I will definitely be clearing away old foliage.

I wonder if Bacillus thuringiensis would work as a biological control or Nematodes aimed at Vine Weevil? I prefer biological control. I use MET52 as standard in my compost to control Vine Weevil but not sure if the nematodes would go for Narcissus Fly larvae as well?

The sun is out! So time to take some photos...

[Anthonyh]

Like Alan, I'm experimenting with covering some of my snowdrops. I have a couple of frames with shade net sides and I put 'wondermesh' (I scrounged some from a friend) over the top during the summer. All tightly sealed.  Only the second year of use, but no sign of trouble yet (although I do worry that if they get in, and get trapped, they could go wild in the frames).

Until recently I hadn't had much trouble, but I had some mushroom boxes full of nivalis I didn't get round to planting out- the Narcissus fly loved those, I assume because they were relatively shallow planted and concentrated in a small area. I had to go through every bulb to check them in the hope of preventing grubs reaching maturity.

I've tried a few insecticides, and I'm a bit sceptical about how effective they are, but I don't have much evidence either way as it's pretty hard to do controlled experiments.  .

[mark smyth]

Narcissus fly don't care if snowdrops are grown in full sun or full shade. They still go for them

[ChrisD]

Thanks folks! Excellent info! Sounds like I need to stock up on Systemic Pesticide? Is there a particular one that works well?

I did read that Galanthus grown in permanent shade were less likely to get attacked? So I have gone for a north wall. Not the best place to show them off?
Does anyone think this works? I will definitely be clearing away old foliage.

I wonder if Bacillus thuringiensis would work as a biological control or Nematodes aimed at Vine Weevil? I prefer biological control. I use MET52 as standard in my compost to control Vine Weevil but not sure if the nematodes would go for Narcissus Fly larvae as well?

The sun is out! So time to take some photos...

A couple of comments; firstly in my garden Galanthus generally dont grow well in positions where they dont get any winter sun. The soil here is very heavy and I suspect tat it is just too cold and wet for them to thrive.

Secondly I would be tempted to try the biological controls as they certainly wont do any harm, however I suspect they wont be very effective either. The Bacillus protein needs to be eaten by the larvae to be effective, it is difficult to see the larvae eating any as it chomps its way through the stem and into the bulb. The nematodes may be too specific, I guess they will attack vine weevils and nothing else.

Sorry to be so negative

Chris

[Martin Baxendale]

I've started using a cheap children's seaside fishing net (the kind with a small net on the end of a bamboo cane) to catch narcissus fly as they settle on snowdrop leaves, then squish them in  the net. It causes less damage than lashing out with my old tennis racket near snowdrop leaves.

[uvularia]

I've started using a cheap children's seaside fishing net (the kind with a small net on the end of a bamboo cane) to catch narcissus fly as they settle on snowdrop leaves, then squish them in  the net. It causes less damage than lashing out with my old tennis racket near snowdrop leaves.

Would you get more control with a squash racket? Useful in tight corners?