Pine needle scale insects feed on the sap from the needles. Pine trees (Pinus spp.) , which grow in U.S. Department of Agriculture plant hardiness zones 3 through 9, depending on the variety, are mainly susceptible to the scale insect Chionaspis pinifoliae. A large population can weaken a pine, but even small infestations can affect the health and appearance of this tree.
What to Look For
Egg-laying feminine scales develop a white armor coating and measure about 3 mm long, while the males are slightly smaller. After they settle down to feed and lay eggs in their adult form, they no longer move. Young mounts hatch from yellow eggs twice annually in mid-spring and midsummer. They move through this early phase and are bright red in colour, so that they are sometimes referred to as reddish spiders. The protective wax armor adults makes treatment difficult, but you can destroy the unarmored red spiders in case you catch them right after hatching.
A Speedy Trim
Light pruning can control minor pine scale coverings. Disinfect pruning shears or a pruning saw by wiping with rubbing alcohol after each cut so you don’t propagate the insects to wood. Only cut badly infested branches back to your nearest healthy wood, or remove the entire branch back to its foundation. Destroy the clippings after ripped so that the insects do not infest another tree.
A high population of ants around or on a pine tree can raise the population of scale insects, since the ants care for those scales so that they could crop the sticky honeydew the scales secrete. Ant bait setup around the tree will eventually kill the ants, but keeping them off the tree and off in the scales is necessary in the brief term. Wrap the pine trunk with a 6-inch broad piece of tree wrap, pushing the wrap to any crevices on the bark. Cover the wrap with a thin coat of a sticky material made for ants that are crocheted. The ants can’t cross the material to make it to the scales above. Replace the wrap every year and remove it promptly if it begins to constrict the trunk.
Horticultural oils and soaps have limited effectiveness since the armor on the scales helps shield them. Large pine trees can also be hard to spray, so well timed soap and oil sprays work best on smaller landscape pines. Apply an oil and soap insecticide once the crawlers are going. You can track for spiders by wrap double-sided tape around infested divisions, and then tracking the tape daily with a magnifying glass before the tape begins trapping the insects. Set a hose-end sprayer to employ 1.5 ounces of 22.5 percent carbaryl pesticide per 1 gallon of water, and then completely coat the pine with the spray. Pesticides are best implemented on dry days, and they may need reapplication at midsummer throughout the second crawler stage. Wear gloves and skin and eye protection when using a pesticide.