Bringing Houseplants Inside: Aphids, Whitefly, and Scale! Oh, My
We are expecting our first real taste of fall this coming weekend. Temperatures will be in the upper 40s F in the evening and only in the low to mid 60s F. On the one hand I am a bit sad that summer is coming to an end. On the other I welcome the cooler weather and the chance to rotate into my fall gardening tasks . . . which are some of my favorite.
The first order of business is that I will soon need to bring in my collection of houseplants. For me this starts with examining each of them carefully. I have already looked at them several times this summer to make sure I liked the container they were in. I made sure that the container size was appropriate for the size of the plant. I trimmed the roots on the bonsai and replaced the soil. They were fertilized. In short, there are only two last tasks to be done before bringing them inside.
I’m not worried about the second task done just prior to the big move. That is washing and cleaning the containers. These seem to get rather crusted with all kinds of dirt and dried on plant parts and even some other nasty organic matter. It is a rather bittersweet task. I hate having to coup the plants up in my house that is cold with low humidity with no rain to clean the leaves. It is the first task to prepare the plants I really need to focus on now. I need a couple of good weeks of weather to get this done. I start when I see that the seasons are definitely about to change.
Examine your Plants from Different Vantages
The first task is to CAREFULLY examine your plants. You are looking for free loaders. The vermin will unduly take advantage of your plants health and vitality when they are enduring your home’s harsh environmental conditions (from the plant's perspective of course). That is why now is the time to try and fix any problem pest you can.
You will want to take in a long range view of your plants. You are looking for major problems like branches that seem to be turning yellow. These will need extra examination to determine why the branch is dying. It could be physically hurt from a recent storm. If the branch is broken it is best to remove it. This type of injury can be harboring disease or even insects. Be sure to sterilize your cutting tools from time to time. This avoids spreading disease from plant to plant. A 1 part Clorox to 10 parts of water should be enough. Or wipe your tools with some rubbing alcohol and let them dry thoroughly before using. Remove all dead plant material like these branches and leaves. My lemongrass always has a large amount of dead blades to remove.
You will want to look closely at the surface of the leaves, the back of the leaves and especially near the tips of stems where the plant is generally new. Insects love these locations. Do not just take a hasty look. I generally turn my plants on their side and look closely at all the back side of the plant. If you only look at a couple of leaves there is a good chance you will miss something.
Insects can take a variety of appearances. Some like scale crowd the stem in almost overlapping bumps. The young scale are whitish and almost translucent while the adults are generally a brownish color. Adults almost always take the color of the mature stem where they are attached. Aphids can take a range of color as well. The light green almost translucent ones are most common. As with scale, aphids will often be seen with ants. Ants use both of these insects and collect “excretions” as one of their food sources. Sometimes you will find red aphids. Look for a small insect that seems to be relatively slow moving or not moving at all with a fairly rotund body. They are probably aphids.
Other insects to keep an eye out for include mealy bugs and whitefly and fungus gnats. Mealy bugs are fuzzy white one eighth of an inch long bug that can fly. Whitefly and fungus gnats are harder to find. That is why it is so important to look at the back side of the leaf. Even though many insects lay teeny weenie little white eggs, whenever I see one of these I just assume whitefly. Fungus gnats are a nuisance in the house. Keep an eye on the top of the soil. You may need a magnifying glass. The larva is hard to see otherwise.
Fortunately many of these pests can be contained and minimized. Fungus gnats are one of the easiest. All you need to do is let the surface of the soil dry out. These little pests feed on organic matter in moist locations. Take away their food and water and they disappear. For the rest it is best to fix your problems before you bring them inside. Scale attaches itself to a specific location and won’t move once their piercing jaws attach to the plant. They just sit there and suck up the plants vital fluids at their leisure. They don’t even have to tip a waitress. Aphids are fairly immobile as well. For these slow moving insects I like to spray every couple of days with oil. Any vegetable oil will work. The best is neem oil. It is even better to add a bit of azadirachtin which is a concentrated compound in neem oil. Azadirachtin works by disrupting an insect’s life cycle change. For example it prevents eggs from hatching and it doesn’t allow larva to go into their pupa state. The oil you spray works by clogging up the air holes in the body of the insect that allows it to “breath”. You are suffocating them. Spray every couple of days to make sure you hit all of them several times.
I also spray every day or two for a two week period with an insecticidal soap solution. Insecticidal soap controls a wide range of soft bodied insects. It is safe to you, your children and the environment. In between spraying with the insecticidal soap I spray with regular water from the hose. You need to make sure to spray tops, bottoms and stems of the plant with a fairly stiff spray. You should do this with both the water and the insecticidal soap. I use the two week time period because that way I have included at least one generation of critters on the plant. I hope that my spraying hits more generations than this. I also hope I have more than two weeks before I need to bring everything inside.
The success of your plant preparation for moving into the house for the winter will be determined by how pest free you are this fall. This system has worked for a great number of years for me. I am not one to drag plants to the bath tub to debug in the winter. I sometimes fail to mist them on a regular basis too. So, I try my best to make sure my houseplants are pest free when they come in to reduce their trauma from my neglect. I am happier too without a pesky fungus gnat helping me drink my tea.