Pine Bark Beetles (Borers)
Pine Bark Beetles are small reddish-brown beetles about 1/4 to 1/3 of an inch long. They are able to fly; they reside in trees and can be found at many altitudes around the world. Though they prefer live trees, they can and will feed on freshly cut stands when readily available. Pine bark beetles are the single most destructive pests which attack pine trees. They are quick to reproduce, migrate and eat so once active on any one tree in a stand, it is important to start dealing with them immediately to minimize casualties.
Pine Bark Beetle DamagePine bark beetles are attracted to pine trees by first smelling the trees sap. Though most trees will emit small amounts of sap naturally, trees that sustain injury due to man or nature are more likely to get beetle activity quicker. Pruning at inappropriate times (like the summer), mechanical damage by construction crews cutting protective tree bark, lightning, drought, disease or insect damage–like that which can occur from termites–are all things that can make a tree more susceptible to pine bark beetles. Once a flow of sap is more than normal, the odds that beetles will find the tree are increased. A normal healthy tree will emit or release some sap that can attract beetles. When a tree is injured and sap runs freely, the odds that beetles will find the tree are greatly increased. Once found, beetles will penetrate the bark and then begin excavating tunnels between the bark and the wood of the tree. These tunnels will serve as egg cavities. Eggs will be laid and when the larva hatch they will immediately begin to feed on the live part of the tree called the phloem and xylem. This feeding will lead them on a random journey, which typically moves around the tree weakening it’s bark to the point of it falling off. Trees that have been severely damaged will shed their bark and appear naked; galleries and tunnels will be visible leaving a sure sign of what caused the damage.
Once the larvae get their fill, they will undergo a metamorphosis during which time they change to adults. This third stage is called the pupa and when ready, they will hatch and emerge from the tree. Their emergence will leave a bunch of new holes through which the attractive scent of sap along with their natural pheromones will attract even more beetles. For this reason it is always wise to treat any tree which you suspect may have a small amount of activity. Trees can withstand a beetle or two but if left alone this initial activity will multiply to hundreds of beetles as new ones are attracted. At this point the survival of the tree is not likely. Most importantly, the adult beetles, which will be emerging, are looking for new trees on which to land and start laying eggs. If you have a stand of trees and one gets an infestation, it is always best to treat as many around the infested one that you want to save. This effort will help prevent the activity from spreading.
