Greenfly and shed skins on a chilli plant

6 tips on how to spot greenfly

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Greenfly, a menace to all, and particularly to chilli growers. Greenfly not only spread disease and drain a plant of its energy they often damage the fruit too. But how do you find them in the early days before they take hold and decimate your plants? Here are 6 tips for early detection.

1/ Look in the new shoots. Although they are commonly found on the underside of leaves, early in the year before the sun gets hot, they get into the tender new shoots where they damage flowers and leaf growth while the are still forming, so look there first.

2/ Use a magnifying glass or zoom in with your phone camera. It is so much easier to find and kill two or 3 today than 300 a week from now. In the picture below you can clearly see two fatties tucked into the new leaves plus a couple of smaller ones. The scars from their bite marks will cause the leaves to be contorted.

Early greenfly infestation on chilli plant

Early greenfly infestation on chilli plant

 

3/ When the sun gets hotter they seem to take shelter. This is when you start to find them lower down the plant among the shady lower leaves. Look for the white shed skins, they are often the most obvious sign of a greenfly infestation.

 

Greenfly and shed skins on a chilli plant

Greenfly and shed skins on a chilli plant

 

4/ Look for twisted shoots as they emerge, this almost always  a sign of greenfly, not some other disease. The greenfly that caused the problem may have long since been eaten by predators, but it is best to give the tip a spray with an organic insecticide to be on the safe side.

 

Greenfly causing twisted leaf growth on a chilli plant

Greenfly causing twisted leaf growth on a chilli plant

5/ Look inside newly forming flowers, if the greenfly get hold before you stop them they will scar the flower tissue and this results in bent and badly formed fruit, more on that here. As soon as the bud starts to open they will get inside. A quick spray with a soapy organic insecticide should do the job, or there are lots in there you should nip the flower off and scrap it. There is no point in allowing the plant to put its energy into growing a malformed fruit, there will be plenty of other flowers.

6/ Look for white shed skins in spider webs or on the soil around the plant. This is the tell tale sign that greenfly are lurking on the leaves above. The shed skins are often mistakenly diagnosed as white-fly when they are just empty skins shed as the greenfly fatten ready to give birth to the next generation.

Hoverfly laying eggs on a chilli plant

Hoverflies, Predators of Greenfly

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The most commonly talked about predator of greenfly is ladybirds, you can buy them online, or collect them from around the garden, often on stinging nettles, which are themselves riddled with greenfly.

Just as effective, and just as common, if not more so, are hoverflies. The flies themselves usually feed off of plant nectar, but the larvae of many hoverfly species feed on greenfly along with other aphids, thrips and any other small insect they can get their teeth into.

I have a few more greenfly than usual in the greenhouse this year, but today I noticed that the battle has turned against them. I have left the doors wide open in the last few days in the hope that some predators might come in, even at night, which means I risk moths coming in, and that means caterpillars. Sometimes the line between good and bad is a fine one.

I discovered a new way of finding greenfly, just watch where the hover flies go. I have never watched them this closely before.

Update – For a bit more on greenfly detection have a look at this later blog entry.

Hoverfly laying eggs on a chilli plant

Hoverfly on chilli plant

This chappy (chappess actually) hovered around the plants from shoot to shoot, only stopping at the ones which had greenfly in the tips.Here you can see her sucking on a leaf, maybe one that is covered with the sweet sticky dew that the greenfly exude, this is also the stuff that ants love. I couldn’t get a picture of her next move, which was to reach in with her back end and lay an egg among the greenfly. One egg laid, then on to the next shoot. Only the shoots with a greenfly benefited from an egg, so hopefully in a day or two a tiny larvae will emerge on each and start munching. They grow quite quickly so in a few days I will have a picture of one. Watch this space.

Greenfly on Chilli Flower

Hidden Greenfly Damage

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Most people know the common reasons why we shouldn’t let greenfly run amok over our chilli plants, they suck it dry of sap and nutrients and they spread disease. One other big problem with greenfly is that they ruin fruit. Malformed fruit is a fairly common problem on chillies and other factors come into play such as environmental conditions, genetics, and diseases, but problems resulting from greenfly damage are often not credited as such because they occur long after the greenfly have gone.

 

Greenfly on Chilli Flower

Greenfly on chilli flower

The above picture shows how they enjoy getting their beaks into the soft flesh of a flower, often the flowers and new shoots are the first parts of a plant to be attacked because they are the most tender and succulent. Once this flower opens they will get inside and feed of the reproductive parts of the plant and the tiny chilli before it has even developed. This results in scar tissue from where they pierced the flesh and the outcome is a chilli that is split, or misshaped. You can see this in the picture below.

Greenfly damaged Chilihuacle Negro Chilli

Greenfly damaged Chilihuacle Negro Chilli

 

 

 

 

 

 

Now the Chilhuacle Negro is an odd chilli anyway, the skin is always matt coloured and leathery, even when it is fully ripe (when it turns brown) and it is never smooth and round, but you can see here that secondary fruits have formed close to the calyx (where it joins the stem). On the right hand one these aren’t even closed, they are split open and you can see inside. Whilst still edible, this will probably start to rot before it ripens, and if you were a commercial farmer it certainly wouldn’t be of a quality that you could sell.

The answer to this problem is that as soon as you see evidence of greenfly, usually the feathery white skins on the leaves below, check your flowers. It is difficult to get at the greenfly inside and crush them without damaging the flowers, so you can use an organic spray, but I think it is best to nip off the flowers while they are young so the plant doesn’t waste its resources growing useless fruit. It will soon grow more flowers,usually they produce many more flowers than fruit anyway, and it ensures you get rid of your greenfly and leave the plant producing a healthy crop.

I have had more problems than usual with greenfly this year, but as documented in a previous blog, by far the worst affected have been the Chilhuacle Negros, these fruits must have come from the first flowers be hit, before I even saw them, and I have picked a few fruits like this now. You can never be too diligent!

 

 

 

 

 

 

 

The Order of Greenfly

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I have long been fascinated by the way greenfly will populate one type of chilli plant but not another, and while chilli plants are generally a tasty target, greenfly are happy to dig into one variety while another variety next door goes unscathed, at least for a while.

Some years I get very little in the way of greenfly, other years, like this one they are more of a challenge but even though they are pest, I still find them strangely fascinating. Their breeding cycle is weird, some are born with wings, some without, and some are even born pregnant.

So I have been observing their progress recently. A few weeks ago i noticed a few on my Chilhuacle negro plants, but not any of the others. Now they have spread a bit, firstly to bhut jolokias, but not Carolina reapers, then to some cajun belles, then to some aji, and yet the pimiento de Padron in-between remain untouched.

An entomologist once told me that that they tend to stick to one variety if they can and so in my greenhouse I dispensed with keeping plants of the same variety next to each other, now I alternate them, so that if one plant is infected with greenfly then they are less likely to jump onto the neighbours. Apparently they just get used to the sap of one plant, and their young will prefer to stay there. They still managed to spread from one chilhuacle to another, but it took a while, the fact that they were spread out bought me some time to squash them.

Anyone done any serious experimentation on this?