Blackfly!

Replies to This Discussion

Permalink Reply by Ewan Alexander on August 22, 2012 at 23:09

Weather-wise it's been a good year for plant pests and a bad one for flowering/fruiting. We've all had muchos problemos - it's no reflection on your hard work! Roll on 2013! 

Ewan (aka Bayleaf the Singing Gardener)

Permalink Reply by gilly on August 23, 2012 at 8:48

Can only suggest the hand held hoover to hoover up the worst of them.

Permalink Reply by Grant on August 23, 2012 at 9:15

I've had the same problems in my garden with green and blackfly. I usually have infestations for the first couple of months of the summer until the cavalry turn up in the form of ladybirds and hoverflies. I think I've seen one ladybird in my garden all year, and I'm not the only person to notice this. Hoverfly numbers seem less than usual too. Conversely I've never seen so many spiders in my garden, and some of them are absolute whoppers!

I grow nasturtium purely because blackfly find them so attractive - I'm pretty sure they favour them to the extent that it keeps them off other nearby plants. I just pick and dispose of any leaves covered in them.

Not sure if you do this already but it's worth growing plants that attract hoverflies, in my garden they seem particularly partial to rocket that I've let run to seed. French Marigolds and poached egg plants (Limanthes douglasii) also seem a favourite.

Permalink Reply by Liz on August 23, 2012 at 12:46

Now you come to mention it, I've seen very few hover flies in my garden this year and usually there are lots. I saw lots of ladybird larvae earlier in the year but very few ladybirds. I think we are possibly looking at the weather as a culprit taking out a lot of the 'gardeners friends'. I usually have a few on nasturtiums but they are usually robust enough to take it however, I've pulled up quite a few plants in the garden this year simply because they are so infested, they aren't thriving. Good tips, Grant, re plants encouraging hoverflies. I've got some gone to seed rocket and marigolds, will investigate poached egg plants. 

I've been very disappointed in the flowering this year, after a great start with wallflowers. Ah well, next year let's hope for some more settled seasons!

Quite a useful Q&A here on blackfly [pdf]

Permalink Reply by Nick G-T on August 23, 2012 at 11:32

Liz, I've just moved into a house on the ladder and have been busy taming an overgrown garden. In the early evenings I have been bitten a number of times by what looks like a small fly, resulting in nasty itching and swelling. Could this be blackfly? I haven't seen any clusters of them or stunted growth in the plants so not exactly sure what they are. Have any other gardners experienced this?

Permalink Reply by Alison P on August 23, 2012 at 17:14

I've had dreadful blackfly this year, but only in my front garden which is very sunny. Ruined a couple of nastursums and marigolds. Oddly the same plants in the back are fine. I'd thought it was because the ones in the front have to struggle a bit more, they are all in pots. Interesting to hear others having the same problems.

Greenfly levels about the same though..

Nicholas, I don't think your flies are blackfly as I'm sure they don't bite. They tend to cover the growing tips of plants, just like greenfly except for their colour. If you were further north I'd say they were midges but I don't think they have conquered Harringay... yet..

Permalink Reply by Liz on August 23, 2012 at 20:41

Same as you Alison, the blackfly are only at the front of the house and in the planters which are in sun all day. They've really only infested the nasturtiums which I grow a lot of but they have ruined nearly all of them. They are also spreading to the sunflowers but the ants seem to be controlling them on those. They didn't touch my marigolds, thank heaven nor the broad beans so there maybe something in Grant's idea of using nasturtium to protect other plants although I love a flowering nasturtium and am v disappointed that I've barely seen a bud this year. Last year I had masses of seeds too, this year a mere handful.

Touchwood, no greenfly yet. 

Permalink Reply by Alison P on August 23, 2012 at 20:58

I'll save you some seeds, I think they could take over my garden if I'm not careful!

Permalink Reply by Grant on August 24, 2012 at 10:32

Broad beans are usually the first thing I find blackfly on so good news for you there! Funny you should mention ants - they have a rather remarkable symbiotic relationship with aphids (http://en.wikipedia.org/wiki/Aphid#Ant_mutualism), 'farming' the aphids for the honeydew they excrete, protecting the aphids from predators and even going as far as to keep aphid eggs safe in the ant nest over winter. It's interesting to watch them do this but also very annoying as each year the first whiff of spring sees all my plants covered in aphids and busy ants!

Permalink Reply by gilly on August 24, 2012 at 17:26

Thanks for that info about ants and aphids Grant ..we were discussing this the other day at edible landscapes fins park, Jo had mentioned she has seen ants bring aphids to plants but now we understand why.  I also know through my wormeries that ants eat worm eggs so they do not help the worms to grow in numbers as well.  I am finding that so many of my pots and spaces in the garden are infested with ants nests, sandy coloured ants they are everywhere!

Permalink Reply by JJ B on August 24, 2012 at 22:40

How bizarre! Sorrry to "rub it in" but this year I've had much less aphid atacks in my garden all round. None at all  on the Guelder rose which usually acts as a magnet.  The beans have only just had their first attack and I haven't seen any on my rose plants. I've a square metre of overflowing nasturtiums with no aphids at all! But these have been interplanted with very abundant calendulas. I've also had a bumpercrop of strawberrries and raspberries. But also many many slugs and snails.

Butu I am in the riot zone off just north of Philip Lane.

Permalink Reply by Liz on August 24, 2012 at 23:55

It's not a complete disaster in the flower department in my garden. A sickly dianthus in the front garden which has shown barely a sign a life for the 2 years since I bought it has suddenly sprung into life and is blooming, marigolds are having a good year, some cheap pansies from Lidl are spreading like weeds across the front garden and the blackberries in my garden are sweet (and appearing at the right time, last year, they were ridiculously early). I also have some rather lovely looking tomatoes.

I have seen no pests in my back garden at all but neither have I seen the normally ubiquitous hover flies. Some things were enjoying the wet like the Melissa which was gorgeous in all the rain and Lavantera seems to thrive no matter what *but* I have seen a lot of blackfly and I was wondering if the weather was playing a part in them thriving. Like you JJB, the snails have loved my garden this year but I've lost very few plants to them, unlike those little aphid critters.

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