Sorry I can’t send a photo but I googled scale bugs and that is exactly what they are. I have been squashing them with by fingers just like I do with aphids. I have alot of ants around and those wasps that eats the eggs and caterpillars. As soon as an egg is laid the ants or wasps eat them it is so frustrating so I bought a caterpillar castle and I finally have a couple of caterpillars. The castles are great. Thanks.
They could also be scale insect if they don’t move. Definitely a photo would help. Often scale insect will attack heat stressed plants, so a bit of extra watering probably won’t go astray, and you can squash the scale insect with your fingers (the actual insect lives under the shell) and often ants will carry them onto the plant, as they feed off the sweet honeydew the scale exudes, much the same way as ants ‘farm’ aphids.
Hi Sandra – a photograph would help. To me – lots of experience but really need to know more about your situation – they sound like aphid mummies. Are some of them bright orange (Aphids or Aphis nerii)?
Read more about them here. The mummies are “good” for your swan plants.
https://www.monarch.org.nz/wp-content/uploads/2008/12/aphids-fact-sheet.pdf
Can you send in a photo, to photos@monarch.org.nz?