What we know about them
They lay between 400-600 eggs
The white cotton wool looking stuff is the egg sacks
They live for Two weeks
I am not claiming to be an expert on mealybugs I am just sharing with you what I know and my own experiences with them.
So it seems that there are two different types the ones you can see and the ones you cant.
The ones you can see live on the plant you will see what looks like cotton wool around the stems of your plant, and close by will be a mealybug. They are white and when I first saw one it surprised me how big they are.
In the picture below check out the long sucking mouthparts that insert into the plant and draw out sap from the plant tissue.
The ones you can't see, these guys are the hidden killers. The first signs are your plant telling you that it is unwell. Look out for signs of pale leaves, dropping leaves, and if it's a cactus shrinking wrinkly or falling stems.
I would compare the symptoms to the same as overwatering.
With the ones, you can see use a cotton bud with rubbing alcohol, they die instantly.
Then I spray the plant with a recipe of
5ml Neem oil - Neem oil stops the growth development
5ml Mild soap
1 Litre water
If your a mum use an old Calpol syringe for a 5ml measure.
This will only last for 14 days so will need to be repeated.
With the guys you cant see, I haven't had much luck in saving my cacti from these because once I had noticed the damage had already been done. I have saved a couple by pulling them up and taking as much of the old soil off, spraying them with my Neem oil recipe and potting in fresh soil.
Ladybugs are a great way to control them too, if I ever get any in the house I just put them on the nearest plant and if there are any mealybugs they will hunt them out and eat them :) If you get ants in your house try not to keep plants on the floor as they feed on the stuff Mealybugs produce, so they will protect the mealybugs against predators.
If this doesn't seem to control them then I go for something stronger an insecticide from a garden centre.
ALWAYS KEEP YOUR INVESTED PLANTS IN QUARANTINE