05-07-2025
- Climate
- The Herald Scotland
Aphids are driving me mad - we must be quick to act
A few weeks ago, I had been surprised to see aphids begin plastering the Sutherland kale with their foul little grey bodies before I had even planted them. What was going on, I don't usually see them till early autumn?
I imagine you might have had the same problem, not necessarily mealy aphid but attacks on the likes of your roses. As with so much, I wondered if the problem stems from climate change.
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It seemed I was right as recent research by SASA (Science and Advice for Scottish Agriculture) has shown. The scientists' data covered last winter and this spring and found that, overall, aphids could be active 3-4 weeks earlier than usual.
Cold winters kill off many hibernating insects, so the milder the weather, the more aphids will survive. In looking at the mean temperatures for Edinburgh and Dundee between December and February, researchers showed that last winter was unusually mild. Edinburgh experienced the 13th warmest winter in 50 years, while it was the 12th mildest in Dundee.
And if that wasn't enough, higher April and May temperatures encouraged the insects out of hibernation early which will give them time to produce even more than their usual number of generations.
We gardeners rely on many different predators of pests like aphids. Wasps, hoverfly and lacewing larvae, ladybirds and birds such as tits can be relied on to predate aphids, but they hadn't built up large enough populations to deal with the early pests. Wasps are especially useful but the nests were still small with few workers feeding hungry larvae.
So how do we deal with the problem? The first thing is to check the plants regularly to spot the problem and to act quickly.
You could use insecticide or a soapy water spray, but that would kill 'beneficial' insects as well as the aphids. Particularly the lacewing, ladybird and hoverfly larvae that live among the aphid colonies. Although turning a jet from the hose on established plants would probably help, you obviously can't do this with young plants.
I'm afraid I have to resort to routine check and squash - unlike me you can wear gloves. Natural predators are mow getting to work now their populations are building up.
Plant of the week
Hemerocallis 'Old Tangiers' (Image: PA)
Hemerocallis 'Old Tangiers' is a later season daylily with bright tangerine coloured flowers with a striking yellow throat.
Later season daylilies are less likely to suffer from Hemerocallis Gall Midge which causes buds to distort and go brown.