It's been a month of Aphid invasion here in the Greater Toronto Area. Their sheer numbers at this time of year is quite threatening. I've seen them feast on everything, from trees (especially Maples, Locusts and Horsechestnuts) to Burning bush, roses, Acquilegia, Spirea, Coreopsis....etc.
|Here you can see the adult and instar (younger) stages of Aphids|
Their first evidence is shiny leaves. They excrete "honey-dew" excrement which rains down on foliage below, giving leaves a shiny luster. This is quite visible on shade trees. Other evidence is their sheer number count. They are clearly visible when 20 to 30 congregate on leaves/stems. Sometimes they have distinctive colours. Black, green, yellow, and white/wooly appearances. Then there's the winged stage of life cycle. You'll notice them flying about when their previous in-star white skeletal remains are left on leaves below. Adults birth mini-me's and they begin to feed voraciously.
|Victim: Rose White skeletal remains can be seen here.|
I believe their numerous presence is due to the unseasonal dry and warm temperatures we've endured already this spring. I cannot recall a May where evening sounds are permeated with the hum of airconditioners instead of birds. Closed windows at night are rare this time of year. It's been hot!
I use 3 natural methods to keep aphids at bay in my garden.
1) Squishing them with my fingers (ok, for those of you who say - eeew, please....just use gloves then). They're just filled with plant juice, so it's a no-brainer. I just run my fingers on the cluster of aphids and squish away. I rinse the area with a light spray of water to dislodge any remaining hanging on.
|Gently squish without damaging new growth.|
2) I spray with a nettle and dish-soap mixture when I see them everywhere. (Steeped nettle leaves in water [it takes 2 days to steep]. Strain and pour water with 1 teaspoon dish-soap in a spray bottle). I use this mix especially where I can't squish aphids, in fear of damaging newly forming leaves. This takes time to prepare in advance, so on the spot care - just take your hose and spray the infested area, (not too hard to damage the foliage) to dislodge them from the plant. They will drop to the ground and eventually dry out from a lack of food source.
3) Prune off the worst of it. This reduces their populations and removes the succulent new flushes of growth they LOVE to feast on. This is a last resort method. Otherwise, you may be removing flower buds forming or stunting growth. But, it is a true winner for reducing their numbers.
|No biggy. It washes off, folks. :)|
Watch - keep your eye on new growth. Aphids love tender young foliage. Looking closely once a week will enable you to take quicker action before population levels increase to where you need chemical controls.
Ants - when you see them climbing on your plants, they are after the honey-dew. They harvest it, by coaxing the aphids to poop more. (Gotta love bugs.) Ants devour their sweet remnants and perpetuate the cycle.
Keep your plants hydrated, by watering the in the morning hours. Spraying the new growing foliage with water isn't the best way to water your plants, but it certainly wouldn't hurt to reduce aphids from multiplying and causing damage. Hose off in the morning hours - this allows foliage to dry out during the day, preventing powdery mildew and other fungal diseases from also forming.
When there are sheer numbers as in my photos, you'll find a Lady Bug (Bird, Beetle UK) or it's larvae form feasting on them, among other predatory insects. I usually leave them a leaf full of Aphids for them to enjoy.
This is not the first time I've seen Aphid populations being so abundant. Cycles in precipitation and weird weather patterns facilitate these blips on the richter-scale of bug life. Not to be overly concerned. Your trees won't die with Aphid attacks, they will however weaken if it is an on-going situation each year. The good thing, as Aphid populations increase, so do their predators. If your tree looks further sickly by summer, contact a reputable arborist to take further action.