Boozy beetle wreaks havoc on lawn mower

The tiny camphor shoot borer with a taste for
boring into gasoline containers. Photo by Adam
Sheffield. 

Every now and then I get a note about a pest so bizarre it's kind of hard to believe. This afternoon I received an email through one of our county offices from a citizen having problems with insects boring into his riding lawn mower gas tank.  He knew it was an insect that made the perfectly round holes, because they were still inside some of the holes, and he was able to carefully extract about 15 of them.

And this wasn't the first time.  His neighbor had a similar experience with his mower being damaged by the little pests the previous spring.

Being good at your job doesn't mean that you know all the answers, but it does involve knowing where to go for the answers. In this case I got lucky.  I put out an inquiry about gas sniffing beetles to entomology colleagues, and immediately got several replies.

Some of my colleagues recalled a paper put out in 2011 by Chris Carlton and Victoria Bayless at the Louisiana State Arthropod Museum.  They had published a scientific note describing cases where a small beetle had been found boring into plastic gas cans.  The authors identified the beetle as a type of bark beetle called camphor shoot borer (CSB), Cnestus mutilatus.

One of the gas cans enshrined in the Louisiana State
Arthropod Museum as a testament to the determined
bark beetle that loves its gasahol.  This can had over 150
holes cause by the beetles. From Carlton and Bayless, 2011.

The finding must have impressed even my Louisiana colleagues because, as they reported in their paper, the can is now permanently stored at the Lousiana State insect museum.

The CSB is yet another insect that's not native to this country.  It was first reported in the U.S. in 2004, and is now found throughout the Southeast from NC to TX. It normally feeds on a variety of hardwoods, but especially sweetgum. In Texas it's more likely to be found in the eastern part of the state.

One entomologist pointed out that these beetles are commonly attracted to his alcohol-baited traps used to collect other bark beetles.  Since most gasoline these days contains alcohol, it makes sense that alcohol may be what's attracting these little guys to lawn mowers.

Aside from patching tanks with duct tape, how can we use what we know about this insect to prevent it from ruining lawn mowers and perhaps causing fiery mayhem from Charlotte to Houston?  A glance at the collection data stored on BugGuide suggests that this beetle is active primarily in the spring (March to June).  So protecting gasoline containers in the spring is particularly important.  Storing gas canisters and mowers in enclosed sheds or under some type of tarpaulin may be helpful, especially in the spring. Keeping the outside of the plastic fuel canisters free of spilled gas also might help.

The last solution might involve finding gasoline that doesn't contain alcohol.  But that might be harder than building a new shed for the mower.