1) Opening the interior of the plant through selective pruning;
2) High-pressure watering wands especially designed for pest control;
3) Natural predator mites and parasites to achieve a micro-environmental balance [see Note 1]; the release of Mite Midges (Feltiella acarisuga); or a combination of both; and
4) A variety of organic and synthetic pesticides [see Note 2].
Note 1: I have had excellent success controlling pest mites on my roses using the beneficial predatory mite called Phytoseiulus persimilis. It enjoys warm, humid weather and reproduces twice as fast as the pest mites. Note 2: Research has shown that mites can quickly mutate to pesticide-resistant strains. If using synthetic pesticides, rotate between two or three different chemical types.
Scales
Description: Scale insects generally fall into two categories: Soft and Armored. Unfortunately, species from both types can attack your roses.
Although many species tend to be host- or host-related plant specific, some may attack a variety of plants. Of the species which attack roses, the most common is the Rose Scale. Other species which attack roses include the Grape Scale, Japanese Scale, Greedy Scale, Soft Brown Scale, Cottony Scale and San Jose Scale, and are just as likely to drive you up a rose cane trying to control them.
Armored scales are about 3 mm in size, known to carry viral diseases, and are less likely to secrete the protein/sugar exudate (called "honeydew") than their cousins the Soft Scales. Despite their mature, oyster-like appearance, these critters are closely related to aphids, mealybugs and whiteflies.
Biology: The lifecycle of scales depends in large part which species is attacking your plants. Generally speaking, eggs are hatched by the female and protected under her shell. Mama scale can produce upwards of 400 eggs, most of which will hatch into "crawlers" and at which point are most susceptible to controls. Natural mortality of these crawlers is high without the use of pesticides. However, enough will find their way to other parts of your plants to cause serious damage.
For the most part, these crawlers don't move too far away from where they were hatched. And depending on their sex, will enter varying stages of nymphal development. Females will pass through two stages as a nymph before entering adulthood. Males will enter an additional pupal stage, followed by a resting phase, before becoming a winged adult. Although males don't live very long, the entire scale's lifecycle, from egg to adult, can range anywhere from 60 to 120 days.
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