BEETLE MATHEMATICS
by Ron Gosnell
Pine bark beetle control requires high treatment efficiency to be successful.
Effective treatment means that infested trees must be treated (peel the bark, burn or grind up into mulch for example) to kill the pine beetles before they have a chance to mature, emerge and fly to attack new trees.
Control organizations must be able to effectively treat a high percentage of infested trees year after year to hold an epidemic in check.
Without effective results, beetle populations continue to grow, people will eventually become discouraged, and give up.
On the other hand, effective treatment in one year can make it easier the next.
The simple table below demonstrates results of different treatment efficiencies, from no control (0%) to 95% efficient control.
| Year 1 | Treatment Effectiveness | Year 2 New Hits | Treatment Effectiveness | Year 3 New Hits |
|---|---|---|---|---|
| 1000 | 0% | 3000 | 0% | 9000 |
| 1000 | 50% | 1500 | 50% | 2250 |
| 1000 | 75% | 750 | 75% | 560 |
| 1000 | 95% | 150 | 95% | 25 |
The math assumes a one to three expansion rate (reasonable until entomologist can determine current population dynamics), no in-flight from outside the control area and no major beetle population die-off from disease, predators or weather for example. Year one begins with 1000 beetle trees in the control area.