The aphids took over our greenhouse almost immediately after we planted it the first year. At first, we did not know aphids were causing the damage to our pepper crop. The aphids got a strong foothold in our greenhouse before we figured it out.
All through the 2014 growing season we battled back wave after wave of aphids on our greenhouse pepper plants. We kept killing those nasty bugs and they just kept coming back.
We have since learned a LOT about what works to control this common (and often destructive) garden pest organically.
How to Spot Aphids:
Get a small hand held magnifier and look for the source of the plant damage.
These are the signs that your plant damage is from aphids.
- You may spot a mass of teeny aphids clumped up the plant stem just under the new leaf whorls (Aphids can be green, grey or black), or the underside of the leaf will have aphids on it.
- Aphids leave white nymph castings all over plant leaves as they go through their lifecycles. Those appear as flecks of white on the leaves.
- Also some shiny sticky honeydew like substance might be on the leaves. That’s what ants are interested in.
- Of course the leaf damage is also characteristic of the problem. Twisted, stunted, curled and sucked!
Not sure Which pest you have? There are a HUGE variety of aphids. Here is a Key to Identifying Aphids.
- Aphids are sap suckers. They take the nectar from plant stems and leaves. This diminishes the plant size, energy and it’s ability to grow and support it’s fruit. The plant is stunted and so are the leaves.
- Aphids often carry virus that are communicated with the plants they attack. This makes them a big problem for some gardeners.
- Aphids come in a myriad of species and attack a huge variety of garden plants.
Ants as Farmers:
Some Ants actually protect and tend aphids on plants to cultivate the sticky stuff aphids produce and ants enjoy. Lovely. THIS is why we have an unending population of aphids in our greenhouse. Ants bring them in!
One solution is to get rid of the aphid farming ants, known as ‘Herder Ants’. All the years we have lived here we have dealt with ants on some level. I usually ignore them outside.
Herder ants protect and herd aphids like cattle for the honeydew nectar aphids produce. It’s no surprise really that they invade the warm lovely warm, humid greenhouse climate. It’s full of yummy plants for their little, fat bodied slaves! How handy.
Spreading this cornmeal mix along the ant trails worked for us. It did take some time but if you don’t get rid of the ants you don’t get rid of the aphids.
- Cornmeal is bad for ant digestion and some say it will kill ants. Scout Ants take it back to the queen and hopefully the hill dies off with her.
- The diatomaceous earth cuts up the ant exoskeleton. This dehydrates and kills the ants. Unfortunately it does not stick to them so it won’t kill the queen. To kill a whole ant hill you will have to find the hill, open it and pour the diatomaceous earth right into it.
- Get more ideas on how to deter ants organically here.
TIP: Once you spot pests or the damage they do on your plant, take control. Remember, organic gardening is all about balance.
You don’t want to wipe out every aphid and bad bug in your garden. Otherwise your natural predators will go hunt somewhere else. Aphids only do a lot of damage when their are a LOT OF THEM.
How to Control and Kill Aphids:
- Strong water spray will wash Aphids off your plant leaves and may be enough for a small infestation.
- Snip off heavily affected plant parts and remove the worst of the pests.
- Directly Spray aphids with this DIY Organic Insecticidal Soap. They die when sprayed… but more keep coming as their life stages mature. Fighting the invasion of the little fat bodied fiends is a constant pastime.
- Pick them off with an alcohol-soaked cotton swab or wipe them off with baby wipes.
- Squishing aphids and scale with soapy fingers is another quick removal method (gross but it works).
- Isolate infected plants as much as possible. Remove a heavily infested and damaged plant if you must.
- Try essential oils. This article is full of great ideas for using essential oils for pest control.
- Import and support Beneficial bugs. Certain wasps, Green Lacewing Larvae and good old lady bugs will eat lots of Aphids. Spiders are encouraged in our greenhouse because they eat pests too. Discover more about bugs that will aid your garden in this article on beneficials.
- Companion planting. We have Marigolds, nasturtiums, petunias and basil planted along the greenhouse beds. They provides us beauty, attract pollinators and aphids. Decoy plants like this can survive some pest damage but still need spraying to ensure the bugs don’t get out of control. Other plants actually deter aphids. Rosemary and thyme are two we use with some success.
I think I have seen one or two spider mites around. Fortunately they don’t like neem oil and soap spray any more than aphids. Scale (which I haven’t seen thank God) is another pest to keep an eye out for. Ladybugs eat them all.
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An Oregon Cottage