It’s a sight that can puzzle even the most experienced gardener: your beautiful Buddleja, the undisputed butterfly magnet of the garden, suddenly develops great splodges of lime green across its leaves.
At first glance—usually accompanied by a squint, a cup of tea and the vague hope that the problem will sort itself out—you might assume it’s a nutrient deficiency, a fungal disease, or possibly some terrifying new virus that has arrived specifically to ruin your afternoon. Thankfully, it is usually nothing quite so dramatic. More often than not, those strange lime-green patches are the result of aphids.
These tiny sap-sucking creatures have turned up for lunch, invited several thousand of their closest friends, and have apparently decided that your Buddleja is the restaurant.
Aphids feed by sticking their mouthparts into the plant and sucking out the sap, while injecting saliva as they go. Where large numbers gather, particularly around young leaves and new growth, this can disrupt normal leaf development and produce a surprisingly convincing imitation of a viral infection. The result is pale, lime-green patches which stand out rather spectacularly against the otherwise healthy dark green foliage. You may also notice that the affected leaves become curled, distorted or slightly crinkled.
So, what should you do about them?
Nothing. Well, not necessarily.
Before reaching for anything more complicated, turn a few of the affected leaves over and have a look underneath. You will probably find the culprits sitting there in little colonies, quietly getting on with the business of destroying your afternoon. Most often on Buddleja, you’re looking at the melon-cotton aphid (Aphis gossypii). They are tiny, pear-shaped insects ranging in colour from pale yellow to lime-green.
If there aren’t too many of them, the easiest solution is also one of the best.
Get the hosepipe or water sprayer out.
A reasonably strong jet of water will knock many of the aphids off the plant. They aren’t particularly good at climbing back up, and you haven’t sprayed anything nasty around the garden in the process. It is also surprisingly satisfying.
If the aphids keep coming back, don’t panic. This is where the garden’s unpaid pest-control department comes in.
Ladybirds, lacewings and hoverfly larvae all enjoy eating aphids, so if you have these creatures visiting your garden, let them get on with it. They are perfectly capable of dealing with an impressive number of aphids without you having to lift a finger. In fact, that’s rather the point of an easy-care, wildlife-friendly garden.
Encouraging a good variety of plants and flowers will help attract these useful predators, and over time they’ll do a considerable amount of the work for you.
And finally, don’t start removing every leaf with a lime-green patch on it. There is no need.
The leaf may look a little unsightly, but the plant isn’t going to collapse in a heap because you’ve allowed a few aphids to have lunch. Leave it alone and, come autumn, nature will do what nature does best and tidy the whole thing up for you.
Which saves you a job.
And, frankly, that’s what we’re aiming for.
