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Black Fly - Blackfly Aphids and How to Get rid of Them

The one good thing about Black Fly - or Blackfly - is that they are easy to see. Sometimes the other closely related aphid - the Greenfly, is not seen until it has taken a stranglehold on its plant meal.

As with all other Aphids, Black Fly is a sap sucker. It literally sucks the host plant to death. A little bit of exaggeration, in that it departs the plant that is giving it a feed, before it dies. A dead plant is of no use to this sap sucker!

As Black Fly are easy to see, we have the advantage of being able to deal with it - getting rid of it - before it can do too much damage. Even when we see the seemingly devastating effect of over-wintered broad beans, all is not lost. In this case, it simply puts the plant back a bit. kill the black fly, and the plant soon recovers.

There are three basic ways of dealing with a Black Fly infestation. Spray with an insecticide or puffer; using a biological control; or preventing them in the first place!

Black Fly Aphid - The Bean Aphid

Blackly - along with the other Aphids - have a quite complicated life cycle, thus making them more difficult to control. For instance, the Black Fly female, is quite capable of producing live young - and eggs - without the help of the male! Live young are immediately able to feed upon the host plant. They do not have to wean on the mother Black fly, so getting in early with control measures is quite important.

As their name suggests, Black Fly can fly! This is part of their life cycle apparatus, in that the female flies off in the Autumn to lay eggs on a host plant which over-winter. The young are born with the ability to fly immediately in early spring; their first point of call is normally the over-wintered broad beans - which make a succulent meal before most other suitable plants start to grow.

More young are born - with wings - enabling a migration to the likes of Viburnum, Honeysuckle and then the later Dahlias. From there, off once again to perform the Winter Egg Laying off site!

Fortunately, the image shows the Blackfly at many times normal size. They are only a few millimetres long! Image by Joaquim Alves Gaspar,

Getting Rid of Black Fly.

The quickest way to get rid of Blackfly is to apply a spray as soon as you see the infestation. This will most certainly be on Broad Beans firstly, followed by French and Runner Beans, then ornamentals such as Dahlias, Poppies and nasturtium later. Later still, they will surface on the Autumnal foliage of Mock Orange (Philadelphus). Viburnum opulus types and Euonymus japonicus europus (The evergreen one).

  • Natural Predators - exist for most garden pests, but our methods of gardening usually keeps these predators away or - worse still - kills the friendly predators off. The Ladybird in particular is an avid feeder on most Aphids - as are the larvae, which most would wrongly recognise as a pest! The rather beautiful Lacewing is another gobbler of Aphids, and much can, and should be done, to persuade Lacewings and Ladybirds to set up home in our garden.
  • Natural Sprays for Killing Blackfly will include those based upon Pyrethrum or Horticultural Soap. These are not the most effective control for getting rid of Blackfly - but they are considered as being 'organic'!
  • Contact Spray of BlackFly include Bayer Sprayday (Deltamethrin). Used directly at the clusters of Blackfly - or other Aphids.
  • Systemic Control of Blackfly - is absorbed into the plant tissue and sap, and is therefore very effective at killing off Black Fly and other Aphids over a period of time. Scotts Bug Clear Ultra is fine but MUST NOT BE USED FOR EDIBLE CROPS!
  • Edible Crops and Blackfly. Bayer Provado ultimate Bug Killer is suitable for most ornamental, and a wide range of edible crops. READ the instructions on the pack to see which edible crops can be treated. The old favourite of Permethrin is not now allowed for use.
  • Overwintered Eggs of Blackfly can be attacked with a general purpose oil based winter wash. Winter Tar wash is no longer applicable!
  • Biological Control - is comparatively expensive, but effective - if you can create the right conditions. The main problem being that there will be a time lag between being able to source the biological control of Blackfly. Together with this, there will need to be enough Blackfly for the biological predators to act upon.



Quick Questions

How long do black flies last?

Blackflies start appearing in the middle of May and the season can last until early July. Each Black fly will only last 2 to 3 weeks in its fly form, you can follow the Life Cycle of Blackfly.

What keeps black flies away?

These work to a certain extent, if the femail is hungry enough, she will still bite.

Make up your own repellant mixture, simply, mix 8 parts water, with 1 part vinegar and add a few drops of spearmint, mint or peppermint. Shake well and put into a spray bottle, spray yourselves and pets, if there is a place where you sit, spray the area. It is a cheap method and keeps away the majority of blackflies.

Wear Light Clothes. Wear light clothes, whites and beiges are ideal, avoid dark colours and try to wear long sleaves and pants if you keep getting bothered.

The final simple method is spearmint, mint or peppermint airfreshners, hang them around where you sit or place an airfreshner in line with a fan to disperse the scent around.

Do black flies die after they bite you?

It is the Female Blackfly which bites, it requires nutrients from your blood to provide food for its eggs. There fore it will bite you just before it is going to lay its eggs. So they do not die after feeding on you, they need to feed on you to survive.

What attracts black flies in the house?

Blackflies enjoy a different environment to our houses, they do not like to stray too far from water. What does attract blackflies to houses are dark colours. White houses attract fewer flies than bright and dark coloured houses.


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