10-03-2013 02:17 PM - edited 10-03-2013 02:42 PM
I would normally suggest pruning off small branches with this on it but would not suggest pruning anything off of a Japanese maple like this one.
What it looks like your tree has is Cottony Maple Scale. Many non-bebeficial insects, like this one, will lay eggs that resemble the eggs of many beneficial insects. Keeping your tree properly fertilized and healthy is the first step to controlling this.
The insects are usually controlled by having a healthy ecosystem inside the tree. This means that applying the proper insecticides, to not destroy and kill your beneficials. Insecticidal soaps need to be applied once the insects hatch but removing whatever eggs you can by hand will give your tree a healthier ecosystem since these are considered non-beneficial.
Each sack has over 1000 scale insects inside it, so getting rid of as many egg sacks would put you ahead of the game.
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