Aphids on my houseplants

Question

I think I have black bugs on my plant since last year and I worked on it for months and then I thought I killed it. I used soapy water and when it did not work I used pesticide. It almost killed my plant but somehow I recovered it.

This year, they are back again and have infested another plant too. One of my other plant now has green colour aphids. Another one has mealy bug ( which I just found out after googling)

I have tried soapy water but it seems to harm the plants and the leaves drop off. I thought I had put too much so I washed the plant in shower with cold water but they are still falling off and the bugs are spreading.

I am not able to understand why my plants are getting infested so often and what can I do to heal them.

Answer 1

Unfortunately, I don't have any photos to go with but I will try to answer some of your questions and give a little bit of additional advice.

What type of insecticide or treatment you choose to use, depends on a few factors, the type of pest, the type of plants, how bad is the infestation, what is the current state of the plant.

I would suggest to start by only using something that has a label on the bottle meant for use on plants. Just because it comes in a bottle, does not mean it is bad for you or you to use in your home. There are plenty of safe chemicals you can use in your home, like insecticidal soap, pyrethrin spray, & neem oil, just to name a few.

The reason it's important to use something developed for plants is because it has been tested/proven to work. How well it works depends on the type of pest and how bad the infestation. A label on a bottle will tell you exactly how much to use, how to use it, and what pest it is used to treat. It will also list some plants that spray is safe to use on. The label will not list all plants, so it is important to test it on one leaf and leave it for 48 hours or longer to see the results. If it is dangerous to that plant that leaf will show damage.

To treat for pest means using multiple applications. One time spray will not work. You will need to do at least one other follow up spray in 2-4 weeks. In the case of mealybug it is best to use more than one approach.

Pests tend to attack weak plants, plants that are under stress. If you do not water enough or water too often this leaves the backdoor open for a pest infestation. Healthy plants get pests less often than unhealthy plants. Or they are able to still remain healthy even with a few bugs.

Answer 2

I had a recent similar incident when aphids attacked one of 3 plants. I don't know why the insects attacked the one plant and not the others since they were identical species and in identical pots and soil. The solution for this situation was to drastically prune back all affected green growth on the one plant, burn the infected shoots and with the problem area drastically reduced use a magnifying lens with Qtip and alcohol to carefully remove all signs of the insects. So far so good, the bad plant is now catching back up to the others.

Point is to catch these problems early by examining plants closely with an eyepiece lens or similar and to gain experience in what to look for and likely places to look (under leaves, leaf axils and so on).

On large plants drastic pruning might not be a good thing since grafted specimens might suffer more from the pruning than from the insects.

Answer 3

I had the same problem with my tomatoes and common sage, it got rectified, you can use an organic insecticide in dilute form to tackle the problem.

I used Neem oil solution with water. Caution: I had used a larger concentration earlier which led drying of my leaves, which is similar to what you got. After diluting the concentration, and spraying it 2-3 times with an interval of 2-3 days, the problem got fixed.

I also massaged the area a bit to manually remove the aphids.