How do you get rid of scale [bugs] from outdoor bushes?

Question:Someone mentioned spraying soap on them, but what kind of soap?

Answers:
If scales are damaging your plants, you might need to take several approaches to control. For oystershell scale on small trees and shrubs, a simple and highly effective practice is to gently scrape the scales off the trunks and branches with a soft, plastic scrub pad. Once dislodged from the protective covering, the eggs soon die.

Horticultural oils also are useful for controlling many scale insects. These are specialty oils refined to allow their use on plants and are sold in many garden centers under various trade names. "Dormant oil," "supreme oil," "superior oil" and "spray oil" are among the descriptions. Mixed with water to a 1 to 3 percent dilution, the oils cover the insects and smother them. Most oils are used during the dormant season, but some of the newer oils allow use after leaves have emerged. (Uses and precautions are on the label of each product. Read carefully before use.)

A well-timed "crawler spray" often is the most effective way to control scales. Newly hatched scale insects are called crawlers because during this brief period they are unarmored and mobile. In this state, they are susceptible to sprays of most insecticides. Common crawler treatments include Sevin, Orthene, malathion, insecticidal soaps and horticultural oils.

The trick is properly timing the treatment because the crawler period is brief and soon is followed by the secretion of the protective scale covering. Below are some general guidelines to help you know when crawlers emerge in the Denver Metro area:

Pine needle scale Late April to early May (with a second generation in mid-to-late July)

Oystershell scale Mid-to-late May

Pine tortoise scale Early-to-mid June

European elm scale Mid-to-late June

Each season can differ, however, and crawler emergences varies across the state. The best way to determine emergence is by sampling infested plants. Do this by shaking branches that contain living scales and eggs over a piece of paper; examine for the presence of minute crawlers. Alternately, on some plants, you can capture crawlers by placing a piece of double-sided sticky tape on the branch.