Once again, we are experiencing a summer of devastating fires, with repercussions that will last decades or even longer. One of the lesser-known ways in which wildfires wreak havoc is the fact that they create ideal conditions for a particular pest, Melanophila acuminata, the black fire beetle. Also known as fire chasers or fire bugs, these beetles are often the very first to arrive at the scene of a conflagration. By using pheromones, chemical signals, and auditory cues, and monitoring temperature and humidity, Melanophila acuminata will fly over eighty miles to a freshly burned forest. Once there, they meet up, mate, and lay eggs, thriving in places most living creatures avoid.

These wood-boring shiny black beetles are 7-11 mm in length and rocket shaped, with stiff bristles on their under-bellies. They are found in Europe, the Caribbean, Central America, North America and South Asia. In addition to zeroing in on burn scars, they show up at lumber yards, sugar mills, tar plants, cement kilns and smelting plants, anywhere they can find hot pipes and equipment. Interestingly, in 1943 an article in the Journal of Economic Entomolgy noted that fire beetles sometimes swarmed in large numbers at football games in UC Berkeley's California Memorial Stadium, presumably attracted by the clouds of cigarette smoke that hung over the stadium during a big game.

Burning trees give off chemicals like ethanol which attract the beetles, too.  But why do they go towards the fire when everyone else is running away? According to the American Museum of Natural History news blog (Dec. 2017), burned areas are usually free of soil-dwelling enemies as well as birds that feed on larvae.

Once they have arrived at the scene of a fire, Melanophila acuminata use sucking mouthparts to ingest tree and plant fluids. Chemical cues from burned vegetation determine the optimum time and place for egg laying. Strong social bonding guides their nesting behavior, provides protection from enemies, aids in finding food, and helps them rear their young.

These crafty critters are able to withstand, extreme temperatures because they use a copper enzyme to create an exoskeleton, like a suit of armor, for strength and insulation from extraordinarily high temperatures.

As if firefighters didn't have enough to worry about, Melanophila acuminata bite. They often mistake a warm-blooded person for a warm burnt tree and try to burrow under the skin to lay eggs. Hundreds of these creatures will swarm and produce a very loud buzzing sound. Evacuees returning to their homes after a fire should be vigilant as these swarms are intimidating and their bites hurt. In fact, sometimes firefighters will wear bee veils for protection from the powerful stings. But the danger of beetle bites is, happily, short-lived: the swarms evaporate in a few days as the burned materials cool. 

The eggs, laid under the burned bark of trees, primarily conifers, cannot survive the repelling chemical defenses of healthy trees. Indeed, the eggs are sometimes laid in wood that is still smoldering. To ensure the survival of the young, the parent beetle secretes a nutritious meal made from microorganisms, fungus, aphids, scale insects and occasionally animal flesh.  Parents groom and guard the offspring to support a healthy brood.

Despite the nasty biting and the damage done by larvae drilling into utility poles, timber structures and fences, fire beetles are actually essential for maintaining the balance of nature. They break down dead and decaying organic matter, recycle nutrients, reduce fuel loads, gobble up aphids and scale insects, and provide delicious larval treats for birds like the black backed woodpecker, another creature who is attracted to burned areas.

In short, Melanophila acuminata are complex, innovative creatures. But we hope they are not causing more trouble (and pain) for our much-appreciated firefighters.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website.  If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.

Photo Credit for Melanophila acuminata by AG Prof. Schmitz