Problem: My miniature lemon tree as well as a mandarin orange (both in large pots and taken indoors during winter due to cold Denver climate), accumulate some sort of white, cacoon-like insect that adhers or grows on the underside of leaves as well as along branches and stems. They appear to be in a cacoon-like stage bound with a fuzz or fine silk-like material. When removed by hand they easily squash into a brown colored paste.

Question: Are these critters injurious to my trees and if so, how can they be eliminated short of removing them by hand as I am presently doing?

In adition to seeking answers/solutions to infestation of cacoon-like insects on trees My Meyer lemon does poorly in comparision to my mandarin orange. The lemon remains skraggy and slow to grow while the mandarin is an excellent performer. Both are potted in large plastic pots containing small gravel about 2 to 3 inches in depth at the bottom with drain holes. Both are potted in good, poroud potting soil mix. I water only weekly and about an hour later, turn the trees on pots on their sides to drain any excess water that accumulated within the basal gravel. I apply a basic lawn fertilizer (25-3-3) about every 6 weeks during the growing season. Still, the lemon is a poor performer compared to the mandarin orange. Neither tree has ever been pruned. Both are about 5 years old, the orange about 3 feet above soil while lemon is only about 2 feet. The orange is always putting on new stems and leaves while the lemon is extremely slow.

It sounds like cottony cushion scale. You can pick the adults or you can spray with an insecticide that has this insect listed. For the crawlers you can place strips of sticky tape ( sticky side up ) (I use double sided tape ). If the crawlers have hatched you will see them as red or orange specks. Its best to allow the natural predators to take care of them for you, but if none are around you will have to resort to the insecticide. Some have used an insecticidal soap with some luck. Most of the scale will be on the underside of the leaves and stems. This makes it hard to reach them with a spray but if your careful you can do it.
Andi