Narcissus fly

[mark smyth]

everyone has been very quiet about the nasty Narcissus fly. This has been the summer they love. Hot all day and flying from morning to early evening. Have you seen them in your garden or any garden you have visited? I saw them in Scotland and in a N Irish walled garden I viisted on Monday. I've lost count of how many I've killed over the last few weeks but I'm annoyed that most were males. Thanksfully the heat and lack of rain for the last three weeks means there are no leaves for them to lay their eggs on.

Here are photos taken this week to show the black one, fawn and three coloured forms.

Do Not kill the small bumblebees that this fly mimics

[Martin Baxendale]

To help those unfamiliar with the narcissus fly, I'll repeat what I've said in previous years around this time:  You can tell small bumblebees from narcissus fly quite easily by the sound they make when flying. Bees buzz but the flies make a high-pitched whining or keening noise that's very distinctive. Also, bees are interested in flowers but the flies go for foiliage, repeatedly landing on bulb leaves. They seem to be drawn especially to colchicum leaves (especially if the narcissus and snowdrop leaves have already died down) and are particularly easy to swat without damage to small plants when they land there.

[mark smyth]

They like taking nectar or pollen from Geraniums

[Martin Baxendale]

They like taking nectar or pollen from Geraniums

They do visit flowers, as Mark says. What I meant was that the flies don't go purely from flower to flower like bees. They'll occasionally visit flowers but spend most of their time flying around looking for bulb leaves, landing on them and sitting on them. The males also fly around a lot looking for females to mate with, and will often pester bees by mistake. So if your see what looks like a small bumble bee bumping into another one then flying off in a hurry, it's probably a short-sighted narcissus fly that's realised its mistake.

[Maggi Young]

Some new photos been posted to the Pacific Bulb Society's wiki pages:
http://pacificbulbsociety.org/pbswiki/index.php/NarcissusBulbFly


also see this page on PBS : http://lists.ibiblio.org/pipermail/pbs/2003-January/012347.html

[gote]

I am asking out of ignorance but is not the flying pattern dissimilar?
I believe narcissus fly is a kind of hover fly?
I mean it stops in mid air and the darts forward.
Göte

[mark smyth]

I havent seen them hovering and their grub looks different

[Anthony Darby]

I spotted one mimicking a buff-tailed bumblebee - i.e. it had a red bum, but tried to catch it for Etta the chameleon before I thought about taking its pic. I haven't seen it since.

[mark smyth]

I had two Narcissus flies in the garden yesterday. They are either late like someone saw in a buln recently or they have ben hiding away because of the rain. Yesterday was the hottest day for a couple of weeks

[johnw]

There was a great discussion on the merits of selling dormant Galanthus bulbs versus "in the green" bulbs at the Chedworth Cottage Garden Society Meeting last February.  John Grimshaw was pro dormant bulbs stating lifting growing bulbs made no sense, I tend to agree and have usually received bulbs from Europe that way with success. Joe Sharman was adamant that "in the green" was the way to go as at least you knew the plant was correctly labelled - if in flower - and that the bulb was not housing a narcissus bulb fly grub. Both reasonable arguments I thought but I avoid "in the green" if possible as this method won't work for transatlantic but reasonably well from our west coast though the plants seem traumatized.

My question is - can one tell upon close inspection if a bulb is housing a grub?  Usually you find out the next year with a no show.  Also has anyone used Provado with success to kill NBF eggs and larvae? The timing would be of interest as a dormant bulb with no roots cannot absorb imidichloprid and a later application would be too late; but maybe like some other systemics Provado can also kill on contact.  Having had a few bulbs with grubs I want to prevent any possibly hatchings from imported bulbs; I have never seen an adult NBF here.  Any suggestions?

johnw - skies black, rain impending.

[Rodger Whitlock]

can one tell upon close inspection if a bulb is housing a grub?  Usually you find out the next year with a no show.  Also has anyone used Provado with success to kill NBF eggs and larvae? The timing would be of interest as a dormant bulb with no roots cannot absorb imidichloprid and a later application would be too late; but maybe like some other systems Provado can also kill on contact.  Having had a few bulbs with grubs I want to prevent any possibly hatchings from imported bulbs; I have never seen an adult NBF here.  Any suggestions?

Examine the basal plate for signs of the small wound the grub makes when it enters the bulb. The eggs are laid at, or near, the soil surface, hatch, and the grub makes its way down the outside of the bulb to the basal plate, then bites its way into the interior of the bulb from there.

However, there's no guarantee that all such wounds will be obvious. As a precautionary measure, I suggest soaking the bulbs in insecticidal solution containing a wetting agent. Remember that these are flies and do not require the use of exotic insecticides to be killed. A synthetic pyrethroid would be more than adequate. Save your imidichloprid for vine weevils and other insects for which there is no other effective control.

You should also gently pinch suspicious bulbs: infested bulbs will tend to feel a little soft because the grub is hollowing them out. I say "tend" because during the bulb selling season, the grubs are not fully developed, and any softness may be undetectable.

Finally, you can always slice a bulb in half to be sure! If it's infested, remove the grub and wash away the feculent mess it leaves. Whether infested or not, dust the cut surfaces with sulfur, allow to dry for a day or two to callus, and plant. This may sound like drastic surgery, but amaryllids can be propagated by twin scaling, so  cutting a bulb in half is no big deal.

[johnw]

Thanks Roger.

re: weevils We are getting good control of them with parasitic nematodes and have seen their populations plummet of late. We will do another application in a couple of weeks.

The imidichloprid is great to prevent aphids on bulb leaves and especially lilies - seems to lessen feeding by lily beetle as well if applied just as the shoots emerge.

johnw

[annew]

I've found dead bees about in my alpine house when I used provado as a systemic to kill aphids on erythroniums. Don't use on flowering plants if possible.

[Maggi Young]

Narcissus Fly: see also these pages :

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

http://www.srgc.org.uk/smf/index.php?topic=204.0

[Armin]

Caught today my 1st. Large Narcissus Fly (Merodon equestris) of the young 2010 season on the window sill.
Probably hatched from my Hippeastrum pot (no other bulbs in the room).
One large bulb does not show any growth. The bulb neck is suspiciously soft
It is the first time my Hippeastrums got infested.
How many will still hatch from such a large bulb?

The narcissus fly made the typical distinctive, quite noisy, sound. I could feel the fibrations when softly touched the back of the fly with my finger.
Unfortunately the fly was short lived. Our cat observed me during making close shots of my object.
She immediately caught it when the fly unintensionally dropped down from the desk.
My cat seemed to be quite happy while crunching the little energy snack  
I'm thinking of now to practise her for an assignment in the garden...