If it runs like an ant...

April 22nd, 2016

If it runs like an ant...

 I'm used to Asian longhorned beetles, part of the B52 fleet of the longhorned beetle family, since my lab has been rearing these invasives under USDA permit for our work toward a 'green' control method. In China or in our quarantine lab, these cerambycids are 'reluctant flyers' and, although they walk on trees, they also seem to be motionless a lot of the time. So, I found it very interesting last summer to meet a very different member of the longhorned beetle family.

Last June I drove to Coal Township in east-central Pennsylvania to look at an area where an outbreak gypsy moth population had eaten all of the leaves off of the hardwood trees on some hillsides. I stopped the car in a residential area where starving gypsy moth larvae were in abundance, resting in large groups on the walls of a garage or walking on most surfaces. As I was looking at an oak trunk I noticed a fairly colorful ant, a blur of black and red, about 5 feet above the ground, running up the trunk. This was the only one of these ants on the trunk. Now, I've looked at many oak trunks in June during my years of working on gypsy moths in the northeast and this seemed out of place: why was this ant climbing an oak trunk?

The 'ant' in fact turned out to be a cerambycine that mimics ants: Cyrtophorus verrucosus. It runs like an ant and it's body size and shape, especially when running, is reminiscent of an ant. It's been suggested that it looks most similar to Camponotus, carpenter ants, that are commonly associated with wood and forests. Adults of C. verrucosus can also be found at flowers in spring and larvae develop in the wood of dead or dying hardwood trees. No one seems to know what the advantage of looking like an ant would be for this cerambycid. However, it seems that this species of cerambycid is not alone, as other species of longhorned beetles that aren't closely related also mimic ants. There must be some competitive advantage to this disguise for these smaller cerambycids; it's possible that looking like an ant provides some protection from predators that don't eat ants.

Ann Hajek--Associate Curator