Narcissus bulb fly

[mark smyth]

and look what I found just now. I'm now -1 N. 'Fairy Gold'. It's larger than I thought it would be for a month old

[Rodger Whitlock]

and look what I found just now. I'm now -1 N. 'Fairy Gold'. It's larger than I thought it would be for a month old.

It could be considerably older than one month. The first narcissus flies of the season seem to emerge when the first warm weather arrives, typically in early May here, and I presume the first eggs are laid and then hatch soon after.

I'll confirm that this is indeed a grub of the larger narcissus fly: the wrinkled skin and the black tubercle at one end (used for breathing iirc) are characteristic, as is the orange-ish feculent mess of digested bulb tissue it excretes. Your photographs also show the staining of the area around the basal plate of the bulb due to rot setting in. If anyone reading is, is married to, or knows a helpful microbiologist, it would be of interest to find out just what organism causes that rot.

One has to wonder if perhaps the grubs harbor the rot organism and introduce it into the wounded bulbs.

[Martin Baxendale]

That doesn't look like the basal plate. The hole is in the side of the bulb. Maybe it is a much older grub and was on its way out to pupate in the soil or whatever they do? Is the basal plate still intact Mark? In which case the bulb may well survive if cleaned up and produce a new bulb or a number if bulbs from the basal plate.

[mark smyth]

Yes the basal plate is intact. The grub went for a swim I can confirm that the black spot is it's a$$ going by the way it moved ?forwards

[Rodger Whitlock]

Yes the basal plate is intact. The grub went for a swim I can confirm that the black spot is it's a$$ going by the way it moved ?forwards

Lucky you!

Looking again at the enlarged version of your photograph, you'll notice that not only is the wound on the side of the bulb but it's very large. These grubs will migrate from a bulb they've totally devoured to another one nearby. As far as I know, a newly hatched grub bites its way into the victim bulb through the basal plate.

In your shoes, Mark, I'd wash the bulb under a hard spray of cold tap water to remove feculence, then maybe a quick rinse with alcohol, and allow it to dry for a day or two before replanting. Packing the cavity with sulfur might also be a good idea: it's an excellent long-lasting fungicide and as Paul Christian once said at a study weekend I attended, it stays where you put it.

[Lesley Cox]

Well I think David Lyttle (NZ Field Trips) is a microbiologist, if you're reading this David? A little after hours project for you?

[Stephen Vella]

I found one here last summer for the first time (grub in a bulb, not the fly itself), so they're here now too. 

Paul if what you say is true as Narcissus fly is not reported to be in Australia, I would suggest you investegate further with what was infected and if you see them again just squash them, forget the chemicals, there would be nothing regerstered for use because the fly is not reported to be here.

cheers

 

[mark smyth]

Dursban was the best one in the UK until it was banned.

"A water dispersible granule containing 75% w/w chlorpyrifos. A broad-spectrum insecticide controlling many pests of agricultural, horticultural and forestry crops."

Other products contain chlorpyrifos.
"Chlorpyrifos is a toxic crystalline organophosphate insecticide that inhibits acetylcholinesterase and is used to control insect pests. Trade names include Dursban (home and garden uses) and Lorsban (agricultural uses)."
http://en.wikipedia.org/wiki/Chlorpyrifos

Acetylcholinesterase
"Acetylcholinesterase, also known as AChE, is an enzyme that degrades (through its hydrolytic activity) the neurotransmitter acetylcholine, producing choline and an acetate group"
http://en.wikipedia.org/wiki/Acetylcholinesterase

[Paul T]

Stephen,

What I found were 3 little grubs in a Crinum bulb.  They matched the descriptions.  I had been told it was in the Sydney region, which was why I was figuring it was the Narcissus Fly.  The bulb itself appeared intact, except that it wasn't growing.  When I checked it out the inside was rotten and these 3 grubs were in it.  I had had the bulb for a few years, so it wasn't something newly introduced into my garden.  I'm trying to remember whether I photographed them at the time.  I know I mentioned it up here, and I "think" I showed a pic.  Using the search function is pointless for me, as it never seems to work properly, so if anyone else can find the reference that would be wonderful.

[Maggi Young]

Paul,  you mentioned it here: http://www.srgc.org.uk/smf/index.php?topic=1188.msg30589#msg30589
 but there is no photo.

[Paul T]

Thanks Maggi.  Maybe I didn't photograph them then.  There were 3 small maggot grubs in the Crinum, in a puddle of dark gunge like is outlined in other descriptions of the damage they do.   

[Rodger Whitlock]

There were 3 small maggot grubs in the Crinum, in a puddle of dark gunge like is outlined in other descriptions of the damage they do. 

Remember that there are two kinds of narcissus fly, the greater and the lesser. The greater is, iirc, Merodon equestris and closely related species, the lesser Eumerus strigatus. The smaller fly has grubs very different from those of the larger fly. Paul's photo of a grub is unquestionably the larger fly, but I wonder if the "small maggot grubs" in his crinum may have been the lesser fly. Its grubs look like small slugs in a way; more importantly, they occur in considerable numbers in the bulbs they have attacked, whereas the larger fly's grubs are usually solitary, only one per bulb.

Incidentally, my earlier advice in another posting to this thread recommending that you wash away the bulb fly's feculence may be mistaken. A discussion of the larger bulb fly at

http://www.pacificbulbsociety.org/pbswiki/index.php/NarcissusBulbFly

specifically says it possesses anti-fungal properties and is better left in situ.

[Paul T]

I had wondered that myself (larger versus smaller Narcissus Fly), Rodger.  Mark's photo (not mine) of the grub is certainly a more substantial beast than mine were, but the Crinum was also a fairly good sized bulb, so I thought it may have been multiples of the larger one due to the extra space.  Still, if it is not here in Australia, when maybe it was something else.  Stephen, do you know of any other grubs that might affect bulbs in a similar way here?  I'm still nearly certain that someone in the Sydney region told me that they get it there.  It would be very nice to know it isn't here and that mine were just some sort of maggot that was an aftereffect of a rotting bulb, rather than the initial cause of it.

[Stephen Vella]

Hi Paul,

there is a caterpillar Spodoptera picta that will totally destroy Crinums and the Lilly borer a Brithys genus will also do the same destruction, eating all foliage and attacks the bulbs.If you dont see the caterpillar devouring all you see is the destruction and excrement, some case's where they pupate to fly off as moths.

There is a white curl grub about 1cm long that loves eating the roots of bulbs(lilies) and soft perennials in pots and well composted gardens.Found in early spring and suspect nothing from above until there is no growth to pull up the plant and find the grubs and no roots or with lily bulbs nothing but excrement.

Need a photo for a positive id and if you see their case's keep them in a jar and watch them pupate...hope its not the Narcissus fly.

[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=3690.0