1. Neem Oil
Neem oil is probably the closest to a safe and organic solution that actually works. Neem does not work right away, because it does not kill on contact. Neem interrupts the insects' natural hormones, and insects "forget" to eat, mate, and eventually die off. Sounds brilliant right? Not entirely, now the downside.
Neem requires physical contact with the insect, which means you have to spray every inch of every plant. Some plants absorb the oil, and it works for quite some time, until there is new growth, then you'll have to spray again. Too much oil on the plants will cause plant burns in direct sun.
The worst con of all, is that neem smells. It's not toxic to humans, but it renders any herb or vegetable unpalatable. I ended up throwing out my cilantro and swiss chards that I worked so hard to preserve.
2. Lady Bugs
Lady bugs are a great way to control aphids, especially in a garden, if you can get them to stay and lay eggs. I would definitely suggest a try if you have an outdoor ground level (or close to ground level) garden. Being on a windy balcony, I have had little success with them. I have refrigerated them, sprayed them with sugar and coke, but they all eventually leave, or die. Lady bugs are extremely sensitive to conditions, if they do not feel comfortable, they look for another place to settle down.
If you've ever sprayed any insecticides before getting lady bugs, I would caution against it. Lingering neem oil for example, sprayed many months before to introduce the lady bugs, still linger and seem to repel them. Again, they are worth a try, especially in the yard. You can grab over 1000 for only $10 from Hirt's Garden.
3. Hydrogen Peroxide / Insecticidal Soap
These do kill on contact, but both of these solutions require actual contact with the insect, but they don't seem to affect eggs. The down side is you have to spray daily, if not more. With a large infected plant or area, the insects will breed faster than you can kill.
4. Sand & Dish Soap
It's so simple and economical, but it works! This method works best for container gardens and indoor planters, but will also mitigate plants in an outdoor space, but you will just need more sand.
- Cover your plant area or planter with 1-2 inches of sand. I use play sand from Home Depot, about $5 for 50lbs.
- Add a little dish soap to a sprayer (I use a cheap pump sprayer) and spray daily until the aphids disappear!
How does it work? Let's look at the life cycle of the typical aphid. The hatch from eggs in the soil, climb onto the plant as crawlers. After they mature, they grow wings and turn into those annoying little black bugs. Yes, these are in fact both aphids.
An inch of sand on top of the soil prevents the winged adults from burrowing into the dirt to lay eggs. Some will still lay eggs on the plants, but that's where the soap comes in. The insects and eggs are washed onto the sand, and if they are not killed by the soap, they'll likely cut themselves on the sand as they attempt to crawl back up onto the plant.
I laid down the layer of sand in all of my balcony planters and indoor planters, sprayed consistently for 2 days. Now, not a single flying insect or larval aphid in sight. Please note that for outdoor spaces, you may never truly eradicate aphids, they are carried on the wind, or may be breeding in your neighbor's planters, but sanding down your planters will slow them down dramatically. Just keep an eye out and spray your foliage about once a week.
So what method is best for you? Let's break it down:
- Neem oil is quick and easy for non-edible plants, if you don't mind the stickiness and the odor
- Ladybugs is the best for a garden, but to get them to stay you need a large planted ground space that's a suitable habitat
- Hydrogen peroxide and insectidical soap are a quick fix for non-invasive insects that you want to kill
- Soap & sand is best for balcony planters or an indoor space