Aphids are small sap-sucking insects that affect virtually every type of garden plant in Ireland. Commonly known as greenfly or blackfly depending on their colour, there are over 500 species found in Ireland and Britain. These tiny insects cluster on the tips of new shoots, buds and the undersides of young leaves, piercing plant tissue with their needle-like mouthparts to extract sap. Aphids reproduce at an extraordinary rate — a single female can produce up to 12 offspring per day without mating, and these can themselves begin reproducing within a week. This means populations can explode from a handful to thousands within just a few weeks in the growing season. Aphids also excrete a sticky substance called honeydew which attracts sooty mould fungus, further disfiguring plants.
Aphids cause leaf curling, distortion of new growth, stunted shoots and weakened plants. Heavy infestations reduce flowering and fruiting. The honeydew they excrete coats lower leaves and nearby surfaces with a sticky film that develops black sooty mould. Aphids also transmit plant viruses between hosts, which can cause far more lasting damage than the feeding itself. Rose aphids (greenfly) distort flower buds. Black bean aphids devastate broad bean crops. Woolly aphids create waxy white colonies on apple tree bark. Root aphids attack lettuce and other plants below soil level, causing wilting.
Encourage natural predators including ladybirds, lacewings, hoverfly larvae and parasitic wasps by planting companion flowers such as marigolds, calendula and sweet alyssum near vulnerable crops. Avoid excessive nitrogen fertiliser which produces soft, sappy growth that attracts aphids. Grow sacrificial crops — nasturtiums are highly attractive to blackfly and can draw them away from broad beans. Inspect plants regularly from April onwards and act at the first sign of aphids before populations build up. Pinch out the tips of broad beans once the lowest trusses have set pods, removing the tender growth that blackfly target.
Blast aphids off plants with a strong jet of water from the hose — most dislodged aphids cannot find their way back. Spray with organic insecticidal soap or neem oil, ensuring thorough coverage of shoot tips and leaf undersides. For small infestations, simply squash aphids between finger and thumb. Encourage ladybirds by building or buying ladybird houses. Biological controls using parasitic wasps (Aphidius) are effective in greenhouses. Avoid broad-spectrum insecticides which kill the beneficial predators that provide long-term natural control.
Aphids are active in Irish gardens from April through October, with peak populations in June and July. The mild Irish spring means aphids emerge earlier than in many other northern European countries. Ireland's consistently moist conditions can actually slow aphid reproduction slightly compared to hot, dry climates, but populations still build rapidly. The relatively mild Irish winters allow some aphid species to remain active on evergreen plants and winter brassicas. Coastal gardens may experience less severe aphid problems due to exposure to wind, which aphids dislike. Ireland's strong populations of ladybirds and hoverflies provide natural control in gardens where pesticide use is minimal.
As an Amazon Associate we earn from qualifying purchases.
Effective pest control solutions with free delivery across Ireland on orders over €75
Shop Now →