In the past month, these insects have infested the garden around the house. They don't seem to be killing the plants but seem to inhibit growth. Although I have a variety of plants (several “tropical” varieties) I have only observed them on Moonflower plants this year. The primarily inhabit the moonflowers and moonflower buds. Buds are thick with eggs with a few tiny winged insects also clinging. They cause little black dots on leaves of the moonflower vine and seem to suck out pinpoints of green color from the leaves. Spraying with permethrin does seem to kill them but I am unsure of the effectiveness because the eggs and bodies of the insects are still stuck to the flower buds after spraying. The plant’s health seems to have improved and many of the stuck bugs are dead. Last season the same bugs may have infested a single or possibly two large tree lily plant(s). The plant was completely covered with the bugs. I believe they are the same bugs although I am not positive. Any ideas what to do about this. Thank you. The county is Anne Arundel...not Howard.
The insects look like aphids, a sucking insect. They can have several generations a year but are usually controlled by predators and parasite activity.
Spraying with permethrin is not a good choice as it kills all insects including beneficials which help keep the pest insects under control.
At this point, monitor the growth of the plants and damage. You can wash off the insects with a stream of water. If not effective, you can spray with insecticidal soap.
Follow label directions and do not spray in high temperatures. See our page on aphids https://extension.umd.edu/hgic/topics/aphids-flowers
We are not sure what a tree lily is. You can give us more information or send photos so we can see what you may be dealing with.
What about the insects that have wings? Are those another form of the aphid or something different?
Aphids can be winged or wingless. Here is more on our publication https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/Landscape/Land...