As I wrote in a previous column, with winter comes the preparation of a trillion insects as they seek shelter from the cold. Some, like the ladybeetle and cluster fly, are looking to spend some time with you indoors, where things are nice and warm. Most will stay outside somewhere cozy and out of view.
But all is not lost for the entomologist in winter time. Even in the depth of winter there are still insects to be found.
And, in a way, it’s easier to find insects in winter.
In summer, insects are abundant. Flowers bloom everywhere, and nobody is want for a meal. Things are not so in the winter, when times are lean for insects -- which makes one particular method of collecting particularly effective in the winter: cooking up your own tree snot.
Tree snot, the result of a bacterial disease in trees, is an oozing of nutritious fermented fluid that many insects are attracted to. It’s sort of like kombucha. If you were looking to find insects in winter, hanging out by a particularly snotty tree would be an excellent place to be.
Tree snot is good, but you can make it better.
Such is the idea behind sugar baiting, in which insects are attracted to an irresistible brew of alcohol and sugar painted onto the trunks of trees. Using such a concoction to attract insects dates back to at least the 1800s, and is a great way to attract things that like sugar and a little bit of alcohol, like undergrads and moths.
I learned how to make moth bait from Mark Mello, a grizzled moth collector from New Bedford, Massachusetts. His recipe calls for two overripe bananas, one pound of brown sugar, one jar of grape (or similar) jelly, one bottle of old wine and two old skunky beers. Mash the bananas and combine all the ingredients in a large soup pot. Heat the mixture on medium heat and stir frequently. Turn off heat as soon as it boils. Let sit for two months.
The best nights to bait are relatively humid nights when the low temperature is above 40 degrees. One of the more prized catches around here are Lithophane moths that begin to fly in February and March, giving you more than enough time to get your bait ready.
In addition to the bait, you’ll need a paintbrush (don’t ever expect to use this paintbrush for anything ever again). Head out into the woods at dusk on a good night, paint some trunks and check on the trunks a couple of hours later. If you strike-out with Lithophane, you’ll at least see some sowbugs.
Back in Victorian England, baiting for moths was so popular that baiters were driven to nailing metal placards to trees in order to stake claim to the best tree trunks.
You should have no problem finding good tree trunks.
Kevin Keegan is a Ph.D. student in the Department of Ecology and Evolutionary Biology at UConn. He studies the systematics and biogeography of moths in the deserts of North America.