Driving just about anywhere right now in the Highland Lakes results in a guts-splattered windshield and pulverized bug bodies all up in your grill. Meet the American snout butterfly (Libytheana carinenta), sometimes called the “snout nose” butterfly, which is currently out in force. Unlike monarchs, which are also at their peak in the Highland Lakes in October, snout butterflies are not migrating. They are, however, definitely on the move.
The snout butterfly is often mistaken for a moth or a dead leaf, especially when its wings are closed. It has long mouthparts, which together with its antennae take on the look of a stem. The underside of its wings have a mottled, fallen-leaf coloring. The topside of its wings are black and orange with white spots that can be mistaken for a monarch.
Snouts are pollinators that only live a couple of weeks — or less in high-traffic areas. Snouts only lay eggs on hackberry leaves, and their green, inch-long larvae only eat tender hackberry leaves.
You might be wondering why you didn’t notice these creatures last year. The snout population booms in years of summer drought broken by large amounts of rain, which is what Central Texas experienced this year.
Drought minimizes the number of parasite organisms that feed off of and eventually kill snout butterflies. Drought is also responsible for putting snout breeding on hold, called a reproductive diapause. A large amount of rain after a drought ends the hold on breeding and allows the snout’s host plant, the hackberry, to continue producing new foliage. The decrease in parasites results in a greater number of snouts living into adulthood, breeding, and laying eggs. Snout larvae often completely defoliate its host, but the good old hackberry keeps putting out new foliage as long as rain is plentiful.
The greater number of breeding butterflies in combination with a seemingly endless supply of host plants can result in four generations. It takes about 16 days for an egg to become an adult butterfly. Male butterflies from other generations breed with the newly emerging females — sometimes even before her wings are completely dry. Once breeding has occurred, a female will stick around the host plant to lay her eggs. The newly emerging males usually move on in search of lesser competition and food. These are the ones making a mess of your car.
Before you grumble about that dirty windshield, you should know that what we are seeing in 2020 pales in comparison to what Central Texas experienced in 1921 after a major drought was followed by 36.4 inches of rain, which fell on Thrall in an 18-hour period. The result was a plague-like occurrence of snouts recorded on Sept. 9-10, with an estimated 25 million butterflies per minute on the move. That adds up to more than 6 billion butterflies.
Snout butterflies are just trying to live their best life during their short lifespan — eating, breeding, and pollinating. They do not mean any harm. By the way, you might not want to wash your car just yet. These messy bugs could stick around through the end of October.
INTERESTING SNOUT BUTTERFLY FACTS
- An average hackberry shrub can support up to 400 butterflies when factors are favorable.
- Snouts fly at speeds of about 5-8 mph.
- Snouts do not migrate; they move around in search of breeding and host plants on which to lay eggs.
- Snout caterpillars can completely wipe out the leaves on a hackberry shrub, but the shrub will refoliate if water is plentiful.
- Record snout populations in Texas have been observed in 1921, 1978, 1996, 2018, and 2020.