{"id":10580,"date":"2019-05-28T08:34:06","date_gmt":"2019-05-28T13:34:06","guid":{"rendered":"https:\/\/uwm.edu\/field-station\/?p=10580"},"modified":"2019-06-26T10:08:36","modified_gmt":"2019-06-26T15:08:36","slug":"luna-moth-5-29-19","status":"publish","type":"post","link":"https:\/\/uwm.edu\/field-station\/bug-of-the-week\/luna-moth-5-29-19\/","title":{"rendered":"Luna Moth"},"content":{"rendered":"

Greetings, BugFans,<\/p>\n

The BugLady\u2019s favorite insect is the Tiger Swallowtail (Mom likes me best), but in the crowded field for second place, the Luna Moth is pretty close to the top.<\/p>\n

Luna moths<\/strong> (Actias luna<\/em>) are in the Giant Silkworm\/Royal Moth family Saturnidae<\/em> (of previous BOTW fame<\/a>), whose family members have ringed eyespots reminiscent of Saturn. The LM\u2019s name came from eyespots that resemble moons (eyespots that make predators ponder whether their target might be different than they originally thought). Actias<\/em> is a small genus with about two dozen species worldwide, and the LM is the only American species. They are found in wooded areas east of the Great Plains (on rare occasions, LMs have made their way to Europe).<\/p>\n

And giant they are, with wingspreads that often exceed four inches. Males and females look pretty much alike; her egg-laden abdomen is larger than his, and his antennae are fancier than hers. Both have what\u2019s called quadripectinate<\/em> antennae, which means that they are comb-like, with four \u201ctines\u201d per unit of the antenna https:\/\/bugguide.net\/node\/view\/754599\/bgimage<\/a>, https:\/\/bugguide.net\/node\/view\/293789\/bgimage<\/a>, and the female https:\/\/bugguide.net\/node\/view\/426762\/bgimage<\/a>. Their long, twisted tails are said to interfere with bat radar, and they also present a false target for predators – bats manage to snag some LMs, but many others get away after the bat mistakenly grabs them by those spectacular tails.<\/p>\n

\"Luna<\/a><\/p>\n

(LMs make photographers sweat (\u201cplease don\u2019t let me screw up, please don\u2019t let me screw up\u2026.). Here are some photographers who didn\u2019t screw up https:\/\/bugguide.net\/node\/view\/20728\/bgimage<\/a>, https:\/\/bugguide.net\/node\/view\/617459\/bgimage<\/a>, https:\/\/bugguide.net\/node\/view\/655366\/bgimage<\/a>, https:\/\/bugguide.net\/node\/view\/917529\/bgimage<\/a>, and (possibly posed) https:\/\/bugguide.net\/node\/view\/1532344\/bgimage<\/a>).<\/p>\n

Warming weather signals them to emerge from their cocoons, which they accomplish with the aid of an enzyme (named cocoonase<\/em>!!) that they secrete to soften the dried silk and of a hard spur at the base of each front wing, which they use to break through it; here\u2019s a YouTube video and of an LM eclosing<\/a> (emerging), and some still shots<\/a>. Then they pump up their wings and begin their short lives as adults. Females emit a pheromone that calls males to her perch. His feathery antennae allow him to sense a mere handful of scent molecules from two or more miles away and to follow the increasingly concentrated scent trail to her. Lunas are nocturnal, and most mating occurs after midnight.<\/p>\n

Adults have neither mouth nor gut, and they live only about a week, dying soon after they reproduce. There is one brood per year here in God\u2019s Country, and two or three in the south.<\/p>\n

Females lay between 200 and 400 eggs, singly and in clumps, on host plants. LM caterpillars feed on the leaves of birch, hickory, walnut, maple, and sumac, and add sweet gum, pecan, and persimmon in the south (they aren\u2019t considered forest pests). They show regional favoritism – LMs in our area prefer birch and do badly if moved to a different food plant. One theory is that LM caterpillars are capable of processing the defense chemicals produced by their host trees, and they may become specialists in detoxifying a particular species. Young caterpillars<\/a> are knobbier than older ones.<\/a><\/p>\n

\"Luna<\/a><\/p>\n

Mature caterpillars become dark red before pupating; they drop to the ground and use silk to wrap themselves in a leaf for the winter<\/a>, camouflaged in the litter of the forest floor. LM pupae are not passive \u2013 if they are disturbed, they will move noisily within their cocoon. Jim Sogaard, writing in “Moths and Caterpillars of the North Woods” tells us that \u201cThe pupa has a clear \u2018window\u2019 through which even dim light can stimulate the brain. Photoperiod likely contributes to breaking diapause [the suspended animation of winter]. If a cocoon is moved, the pupa within may noisily reorient itself to the light.\u201d Here\u2019s a nice stage-by-stage series.<\/a><\/p>\n

A two inch long LM caterpillar looks like a feast for any predator that finds it despite its green camouflage, but the caterpillar has a bag of tricks that includes rearing up on its back legs, warning its would-be attacker by making clicking sounds with its mandibles, and then regurgitating the noxious contents of its intestine.<\/p>\n

\"Luna<\/a><\/p>\n

LMs are not common, and they are becoming less so. Their natural predators include bats, owls (one source told of a Screech Owl that fed on males that came to visit a female calling from a branch), spiders, and toads.<\/p>\n

Human activities also impact them:<\/p>\n