Within the last few months I have picked up my weekly garden newspaper, turned to the first page to find out another foreign insect has emerged in the UK. Is it because our climate is getting warmer which means insects that are coming in on fruit and vegetables are surviving? The answer is—most likely.

It is certainly the case for one new species which is being seen in warmer areas like London and among other southern parts of the UK.

You may have read about, or watched on the news about the Southern Green Shield Bug Nezara viridula. It was first seen in 2003 and has now been confirmed as a 'problem pest' because of more regular sightings in people's gardens.

The bug is native to southern Europe and destroys valuable vegetable crops, as well as many plants. Currently it does not pose a serious problem like an outbreak, but as the climate is getting warmer horticultural organisations are warning gardeners and agricultural farmers to be on their guard.

The easiest time to identify them is when they are very young, on the underside of leaves. They appear as a cluster of red and black dots, usually next to white small eggs. It is strange because when I first saw the picture I instantly thought Harlequin Ladybirds!

Here is what these

bugs will look like; you may even have come across them!

As they grow into adults they will be much harder to identify, as our native green shield bug looks very similar.

Have a look at these
pictures to give an idea as to what the Southern Green Shield Bugs look like through their life stages. The markings are not always exact so just use it as a guide.

The adults are strong which gives them the ability to fly for miles which increases the breeding range. This is how they managed to spread when they came into the UK in 2003. It is almost certain they came in from a delivery of fruit.

So, the big question is 'What can I do if I spot some?' Firstly, it depends on what they are currently living on. I say this because I personally do not recommend using chemicals on fruit and vegetables. Saying that, if the infestation is very bad then you will definitely need to take action. Have a look at the following methods:

1. There are chemicals containing bifenthrin, which would be the best to control the infestation. A WORD OF WARNING: Make sure that you read the instructions fully, especially if using on vegetables. It will tell you on the box if it is suitable or not.
2. If the infestation is similar to the first picture in my article, then try using a hosepipe and blasting them off. Of course, you will have to be careful not to damage delicate plants but it will be worth a try before resorting to chemicals.
3. In the USA they are currently controlling the bugs with parasitic wasps and flies. If you have plants that attract insects it will help to deter or control nuisance pests.

One important point is to make sure they are definitely Southern Green Shield Bugs, as our native species is not harmful to our plants.

The Southern Green is a sap-sucking insect; damage is not usually visible until they have disappeared onto another plant a few weeks later. So, the key is to be vigilant and check underneath the leaves of your prize-winning vegetables and plants on a regular basis!

If you think that you have a collection of these Southern Green Shield Bugs, then please contact the specialist organisation called
Garden Organic . They are monitoring the spread of these insects carefully.

Nigel's Gardening Hints and Tips
Archive

Helleborus a.k.a. Nigel

30.11.09 Front Page

Back Issue Page