How are lightning strikes and pine bark beetles connected?

On Monday, October 5th, 2009 (about a year ago), at one o'clock in the morning, lightning struck a pine tree near Memorial and Antoine. My client and his family were home at the time and heard the crack. I arrived at the tree at 9 o'clock on Tuesday morning, 32 hours later, and pine bark beetles were already present on the tree.

I have heard that they can attack a lightning-struck pine within 12 hours, but 32 is the fastest interval that I have personal experience with, and it's pretty fast.

(Another note on this property, just a month earlier, the next-door neighbor had a pine succumb to pine bark beetle attack and had all of her trees treated with preventive bark application. The property owner decided not to tell me of this event, because he wasn't ready to have me "sell" him a preventive bark application.)

In another case, just a couple miles west, at Memorial and the Beltway, I inspected a lightning-struck pine that didn't appear to have pine bark beetles on it until about 10 days after the strike (this, by the way, was in August 2009).

So, what is the relationship between lightning and pine bark beetles? This has been studied by several researchers since the 1940s. What is believed is that these little critters are attracted to the pine smell emanating from the fresh wound of a lightning strike. A lightning strike is very stressful to the tree, and most beetle attacks are successful.

If the tree is super healthy, however, it could conceivably exude enough oleoresin to smother the attacking beetles. This a huge gamble; therefore most pine bark beetle experts recommend immediate removal following a lightning strike (pines, not necessarily other trees).

I have seen this phenomenon.

On F.M. 2920 in Tomball, TX, I was inspecting pine bark beetle damage in the far rear of an acreage property, and I came upon a grand old pine with an old lightning scar on it. It had several years' worth of callus woundwood on the scar. It also was peppered with pitch tubes at the base. Grayish-pink, smooth and weathered was their appearance, with no holes. Signs that the tree correctly suppressed the attack with oleoresin exudate.

So it does happen. Heck, we look at pines at least once a week with old lightning scars on them. Not all are attacked by pine bark beetle. So, immediate removal for a lightning-struck pine? I guess it's a smart practice, if you're a forester and dealing with hundreds of pine specimens on a plot. That happens to be a common difference between arborists and foresters. Foresters are always saying take down the tree. Arborists are (or should be) always saying "hold on a sec."

This is why I say with such confidence in another post on the topic that good soil nutrition can reduce the risk of pine mortality even following a lightning strike. That said, I usually don't protest too loudly to a recommendation for removal of a (recently) lightning-struck pine, largely because I seldom see a pine in the urban/suburban setting that is operating on all eight cylinders.

Please feel free to leave a comment or send an email. If you're looking for a TCIA Accredited Houston Tree Service or Certified Arborist, call the company I've worked for since 2002, Bartlett Tree Experts, at 713-692-6371. This is my personal blog--it is not affiliated with Bartlett Tree Experts.