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Welcome to the CountryLife Gardening Blog, written by our horticulturist to provide you with the best tips & advice for all things gardening!  We have been shortlisted for Best Lifestyle Blog in the Littlewoods Ireland Blog Awards 2016 Company Category. 

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Dealing with Whitefly and Spidermite

by CountryLife Gardening | Jul 02, 2015

Whiteflies and spider mites are two of the most destructive pests you’ll find in the greenhouse
Whiteflies and spider mites are two of the most destructive pests you’ll find in the greenhouse. They both cause damage to plants by feeding within the plant tissue.

However, their feeding behaviours are quite different. Whitefly feed within the phloem (food-conducting tissues) essentially they are sucking plant fluids from the phloem, but their eyes tend to be too big for their bellies and they take too much – this excess is then exuded as honeydew which serves as a growing medium for black fungi. Spidermites, tend to feed within plant cells, reducing the plant’s chlorophyll and moisture content and its ability to photosynthesize. Of course, this creates serious consequences for the plants themselves.


How to treat:

  • Yellow sticky traps are helpful for monitoring and suppressing adult populations of white flies - Apparently whiteflies are attracted to the color yellow and then cannot free themselves from the glue
  • Insecticides whiteflies can build up a resistance to pesticides, make sure to alternate your use different insecticides
  • Use soapy water: spray wash your plants with soapy water, taking extra notice of the underside of leaves where the insects live, apply at the end of the day to avoid any burning to foliage. This will only kills the adult insect. Repeat every 3/4 days for as long as necessary
  • Plant marigolds - they tend to repel whiteflies


How to identify:

Look at the surface of the leaves, paying extra attention to the underside of leaves as this is where they will attack first. Your leaves may have yellow blotches on them. Eventually, they will suck holes right through the leaves. Other signs to watch out for are wilting, spotting or discoloration of the leaves. Depending on the species of spidermite they may leave a white webbing on the plant.

How to treat:

  • Wash and wipe plants regularly. You can use water or a solution of tepid soapy water like above. If you can bring the plants outside and spray down with a hose
  • Rubbing alcohol will kill spider mites, pour a little onto a clean cloth and wipe the underside of the leaves
  • Remove badly infected parts of the plant immediately remembering to pick up any leaves that have fallen off the plant. Put them in a ziplock plastic bag and throw in the bin
Written by Jean

Here to help! - remember if you have any questions feel free to pop into one of our garden centres or you can contact us on our Facebook and Twitter pages and email us at:

Like what your reading - then why not nominate us for the Irish Blog Awards 2015. #bloggies2015

Like what your reading - then why not nominate us for the Irish Blog Awards 2015. #bloggies2015

Jean's Bio

Hi my name is Jean, I am a horticulturist with CountryLife in the Ashford branch. I grew up on a farm where we always had a veg garden, so you could say that horticulture and agriculture is in the blood! I studied Landscape Horticulture in UCD and worked part-time in Fernhill Garden Centre, Athlone while I was in college. After graduating I worked in Landscape Architecture for three years before returning to the Garden Centre trade. I began in Keane’s Garden Centre, Kilcolgan, Co Galway and returned to Fernhill Garden Centre for three years before joining CountryLife.  Being a horticulturalist is a great job, you are surrounded by nature every day and there is always something to be done. Meeting customers and giving the advice is very rewarding especially when they report back positive results. I love growing my own fruit and veg and I’m always trying new varieties and ways of growing. The seasons are always changing and while the weather is challenging in Ireland, I believe we grow the best produce in the world.