One of the most elusive, yet stunning moths found in Missouri is the giant leopard moth (Hypercompe scribonia). These moths are in the the Erebidae family, same family as tiger moths and go by other names such as eyed tiger moth or great leopard moth. Their common name was bestowed upon them in 1790 and comes from the leopard-like pattern on their wings. These are the largest of the tiger moth species found in the Eastern United States. Males are larger than females with a three-inch wingspan and over all body length of around two inches. Both males and females have bright white wings covered in black spots, and blotches. Some spots may be hollow, or open, others are solid. Their abdomen is bright blue with orange spots and males have thin yellow stripes down the side.
While they are considered common, they are rarely encountered because of their nocturnal habits. Many moths will become active right at dusk, giant leopard moths seem to be more nocturnal than their counterparts and are encountered long after darkness falls. Males are attracted to lights at night and in some areas may congregate in large numbers at porch lights or pole lights. Females on the other hand rarely show up at lights and no one seems to know why. Moths are known to be attracted to light and there is no definitive answer as to why, just a lot of theories. Since moths are unable to answer the why, we are left with conjecture, but the most commonly held belief for this is because it confuses their navigational system.
Moths have evolved to travel by something called transverse orientation. It is similar to humans keeping the North star in our sight to navigate where we are going. Moths keep the moon visible to them in a certain position for the same reason. This helps guide them on their nightly travels in search of food and mates or during migration events. What evolution did not take into account was the endless flood of man-made lights that distract an easily confused animal. It is always best to turn lights off at night if not needed. Not only does this conserve energy, but it helps our night flying insects safely navigate the night, and not be distracted by these artificial moons.
Moths are often fodder for other animals and find themselves prey to birds, bats, and other small mammals. Mother nature equipped the leopard moth with an ingenious adaptation…ears! Bats use echolocation to capture their insect prey, and many moth species have evolved to avoid this bat equivalent to sonar. Using the ears located near their thorax and upper portion of their wings to “hear” the vibrations and sounds of the echolocation being sent out by the bat they will emit a sound of their own to confuse the bat then drop from the sky avoiding capture at the last minute. Ingenious!
Females will emit a pheromone (chemical perfume) to attract males, which are capable of smelling her fragrance from about a mile away. Mating may last over twenty-four hours, after which the female will lay her eggs on a wide variety of vegetation including maple, violet, willow, dandelion, and cherry to name but a few. It is highly likely the female perishes shortly after laying her eggs. The eggs will hatch and the young caterpillars will overwinter in leaf litter.As soon as the temperatures begin to rise in the spring the caterpillars will become active and seek food. These little munchers grow rapidly and complete their life cycle in a matter of weeks. The caterpillars of this species are one of the infamous "wooly bear' caterpillars. They reach lengths up to three inches and are covered in dense black hair with reddish-orange or red colored skin visible between the rows of hairs. They are unmistakable. Many caterpillars with hairy bodies have urticating hairs that can be flicked or released when carelessly handled. These hairs can be irritating to human skin and predators will avoid them for the unpleasantness of the experience. This particular caterpillar is harmless and does not use their hairs in such a menacing way. The hairs are however very dense and stiff and would be uncomfortable for a predator to consume, therefore they are probably not the first choice for those animals who have caterpillars on their menu.
Adult leopard moths do not feed, as they do not have fully developed mouth parts. Instead, they consume so much food and nutrients as a caterpillar they merely concentrate on mating and egg laying in their adult stage. Many of the plants they consume have toxins in them that would make them unpalatable to would-be predators and they most likely gain some protection from this aspect of their diet. Predators, when faced with a potential meal will think twice if they know it will taste bad or make them sick.
Giant leopard moths will flash their bright colored abdomen and advertise they taste bad in something called aposematic coloration. Think of the monarchs, with their bright orange wings….predators have learned to avoid that color in nature and consequently the monarch has few worries about being eaten. The same holds true for the giant leopard moth.
When disturbed these moths have a unique defense mechanism, to deter possible predators they will curl up their abdomen and remain perfectly still or they may drop from the surface they are resting on, in a display of faking their own demise. Throughout nature we see animals using this strategy to avoid being eaten, so it must be beneficial to avoiding predation. Dead things are not as readily eaten as live prey.If that doesn’t work to distract a predator they have something else up their little moth sleeves. They will release a yellowish liquid from their thorax, near their eyes. This fluid is distasteful to would-be predators and is sure to leave a bad taste in their mouth. It is described as tasting bitter, and I am uncertain who sampled this yellow goo to come to this conclusion. I suppose some individuals will do anything in the name of science, all I can say, is better them than me.
Nature is full of surprises and often the most unique and unusual of these come in the smallest packages. Giant leopard moths carry a moniker that brings to mind large predatory cats, but they lack the hunters spirit. They instead do their best to avoid predation by implementing all the little tricks nature equipped them with. Their unassuming lives will occasionally intersect with our own and we should take a minute to appreciate the beauty of Missouri’s majority, the insects!
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