"What a thousand acres of Silphiums looked like when they tickled the bellies of the buffalo is a question never again to be answered, and perhaps not even asked." -Aldo Leopold
Fall Webworm Moth Hyphantria cunea (Drury, 1773), fam. Erabidae, P-no. 930319 Host plants: Extremely polyphagous. The recorded hosts are a wide variety of herbaceous and woody species in 50 plant families, encompassing over 600 species worldwide. Date found(s): August 23, 2025; October 17, 2026 Location(s) found: Tyson Research Center, St. Louis County, MO; Hughes Mountain Natural Area, Washington County, MO Notes: Two distinct phases, red-headed and black-headed, of fall webworm moth caterpillars are sympatric in Missouri. These two phases have been shown to have distinct food preferences and ecological characteristics. In work conducted by Makio Takeda (2005), he found that the red-headed form was univoltine in Missouri and fed mainly at night. The black-headed form were bivoltine and fed without a clear day-night rhythm.
You can learn a lot by observing a nice sized tent full of fall webworm caterpillars. Tap on a nest and you may see hundreds of caterpillars begin to jerk and wiggle in unison. This synchronized behavior is a defensive tactic. To a predator like a bird or an arthropod, the sudden, rhythmic movement of the entire mass makes it difficult to target an individual caterpillar and may even seem like a larger, more intimidating organism. Tents of this species often encompass entire branches, including the terminus. Unlike the similar eastern tent caterpillar (Malacosoma americanum) that build their nests in the crotches of limbs and then leave their nests to feed, the fall webworm builds their nests around the leaves on which they feed. When they have stripped a limb of its leaves, they will evacuate the nest and build another.
I shared photos of caterpillars of the goatweed leafwing last year. Last month, the WGNSS Nature Photography Group went to Don Robinson State Park in Jefferson County, MO for our annual late season caterpillar hunt and found quite a few of these guys on thier croton host plants. I was pleased to get a nice photo of a couple of active late instar larvae pictured here.
Brown-hooded Owlet Cucullia convexipennis (Grote & Robinson, 1868), fam. Noctuidae, P-no. 931513 Host plants: Specialist hosting on goldenrod (Solidago spp.) and other Asteraceae family members. Date found(s): September 12, 2026 Location(s) found: Don Robinson State Park, Jefferson County, MO Notes: Due to the apparent lack of high concentrations of toxins in their hostplants that are sequestered by many lepidopterans for defense, the aposematic coloration exhibited by the brown-hooded owlet is potentially a case of Batesian mimicry. Although the specific model species has not been identified, caterpillars and other insects use yellow, black, red, and white color combinations to advertise their toxicity.
Fawn Sphinx Sphinx kalmiae (J.E.Smith, 1797), fam. Sphingidae, P-no. 890118 Host plants: Specializes in woody members of the olive family (Oleaceae), such as ash (Fraxinus spp.), and fringe-tree (Chionanthus virginicus). Date found(s): August 16, 2026 Location(s) found: Loggers Lake Recreation Area, Shannon County, MO Notes: The species epithet, kalmiae, is a misnomer that, unfortunately, has created a misunderstanding about the natural history of this species that continues to this day. Because of the name kalmiae, early entomologists assumed the moth’s main host was mountin-laurel (Kalmia), which are not even true laurels. In reality, field data has shown that the caterpillars heavily favor plants in the olive family (Oleaceae). The kalmiae name was given to honor Pehr (Peter) Kalm, an 18th-century Swedish botanist and apostle of Carl Linnaeus, and not in reference to laurels. The name Fawn Sphinx has been suggested and is now becoming more widely accepted.
Black-etched Prominent Americerura scitiscripta (Walker, 1865), fam. Notodontidae, P-no. 930030 Host plants: Feeds on members of the Salicaceae Family, including poplars (Populus spp.) and willows (Salix spp.). Date found(s): 26 August, 2026 Location(s) found: Logger’s Lake, Shannon County, MO Notes: The WGNSS group came upon the individual pictured here in Shannon County in August of 2026. When it realized we discovered it, we were in for a short but thrilling experience. The caterpillar arched its long anal prolegs over its back, extruded the yellow and red portions thereby doubling their length, and then thrashed them about wildly in an obvious attempt to threaten and dissuade us. Unfortunately, this act lasted merely seconds, and it could not be coaxed into a repeat performance after we had set it up for photographs. If this method of dissuasion does not do the trick, the caterpillar can spray acid from a gland in its thorax.
Green Leuconycta Leuconycta diphteroides (Guenée, 1852), fam. Noctuidae, P-no. 932026 Host plant (s): Hosts on a variety of Asteraceae family members including fleabane (Erigeron spp) and goldenrod (Solidago spp). Date found(s): 28 June, 2026 Location(s) found: Pinewoods Lake Recreation Area, Carter County, MO Notes: Due to its host plant preferences, look for this moth in meadows, fields and prairies. If you plant native composite wildflowers, you may even have luck in finding them in your own backyard. The adult moth is a stunner and is often a popular subject when arriving at blacklights. It has received a common nickname in mothing circles—the “mint chocolate chip moth.”
Black-waved Flannel Moth Megalopyge crispata (Packard, 1864) P-no. 57a0038 Host plant: Not recorded Date found(s): 16 August, 2026 Location(s) found: Loggers Lake, Shannon County, MO Notes: In early to mid-August we found an abundance of these mid-instar black-waved flannel moth larva, literally dozens in this timespan. I got used to pretty much ignoring them, but recording them and the variety of hosta plants these generalists use. During a WGNSS trip, it was discovered that one of these was a bit more interesting than the others. In its downy white fluff, it held some sort of eggs. We pulled out the high magnification lenses to make sure we had a good chance at identifying these back home. Eggs of some parasitoid first came to mind, but these did not match anything obvious with those groups. After a Google session, we found these are most likely eggs of an assassin bug (fam. Reduviidae). It is unknown how or why the eggs found their way onto the caterpillar as assassin bugs typically oviposit on the surfaces of plants. Either the assassin bug chose a weird location to oviposit or perhaps the caterpillar collected these when moving about.
Mid-instar Megalopyge crispata larvae with Reduviidae eggs
Witch Hazel Dagger Moth Acronicta hamamelis (Guenée, 1852) P-no. 931434.5 Host plant: Found on Ozark witch hazel (Hamamelis vernalis) Date found: 15–16 August, 2026 Location found: Logger’s Lake Recreation Area, Shannon County, MO Notes: The WGNSS Entomology and Nature Photography groups had a great joint overnight trip to Logger’s Lake this past weekend. Obviously, among the several entomofauna groups we focused on, caterpillars were high on our list. The species pictured here was one of our most exciting finds. During my studies of field guides and online sources to determine new caterpillar species to look for, the witch hazel dagger moth caught my attention. Southeastern Missouri has plenty of its obligate host plant afterall. However, after looking on iNaturalist a couple of years ago, I discovered there were no documentations of this species in our state. Checking with the Heitzman catalogue, I found that there was only one recorded observation in Missouri—from 1889! I still kept this species in mind; there were a few documentations in Arkansas and eastern Kentucky and Tennessee, and as I mentioned, the host is abundant in Missouri.
During our caterpillar hikes this past weekend, we were delighted to find seven Acronicta hamamelis larvae at various stages. I collected a couple to take home and hopefully rear to adults. The more advanced individual spent the next day feeding on my ozark witch hazel and then changed to its warm pre-pupal coloration. It has since made a cocoon and I hope to see an adult eventually.
Promethea Silkmoth Callosamia promethea (Drury, 1773) P-no. 890079 Host plant: Found on buttonbush (Cephalanthus occidentalis) Date found: 28 June, 2026 Location found: Pinewoods Lake Recreation Area, Carter County, MO Notes: I shared this species in an exciting finding and rearing experience last season here and here. To my delightful surprise, the WGNSS Entomology Group found four early instar (L1/L2) caterpillars during a trip to Pinewoods Lake in late June of this year. Since I have a buttonbush in the yard, I decided to bring them home to rear.
Early instar (L1/L2) Callosamia promethea larvae on buttonbush host.
I was getting a bit worried about my buttonbush by the amount of material these four guys were putting away. Nevertheless, I continued to supply them with fresh branches and photographed them during their development.
Mid instar (L3) Callosamia promethea larvae on buttonbush host.
Late instar (L4/L5) Callosamia promethea larvae on buttonbush host.
By mid-July, the caterpillars were fully developed and all four went into cocoons with 2-3 days of each other. From what I could find in literature, it seems that this species is bivoltine (having two broods per season) in our region. However, I was not sure if these guys would eclose this season, or if I would have to wait until the spring to see the moths. If you paid attention to the featured image at the top of this post, I assume you have guessed already.
Adult male Callosamia promethea. Notice the dorsal coloration and patterning that is reminiscent of a dark swallowtail.
The individual that Chris reared last season turned out to be female. After reading about the interesting sexual dimorphism in the adults of this species, I was eager to see and photograph a male. As you would expect, female Promethea moths are nocturnal, do not feed, and are eager to mate and lay eggs. The adult males are just as eager, but are diurnal and with different color and pattern. They typically fly in the afternoons, searching for females with which to mate. Their patterning suggest that they may be Batesian mimics of distasteful day-flying swallowtails, e.g. pipevine swallowtails.
The fourth and final adult Callosamia promethea to eclose turned out to be this gorgeous male.
This season’s cats turned out to be three males and a female, and there is an interesting story to be told here. All four eclosed within seven days. The first two were male. I photographed these and released them in my neighborhood. Early in the morning, a couple of days following the release of the second male, I found a gorgeous female had eclosed and was letting her wings expand in their flight cage. In mid afternoon of that same day, we noticed a male Promethea moth trying to get into the screen porch! I assume, but do not know for certain, that this was one of the males I released previously. I opened the door to the screen porch and he eventually found his way in and headed directly to the cage holding the female. I opened the cage door and he shortly made his way to her.
Mating Callosamia promethea. A sibling love affair?
I am always shocked by how quickly moths want to deposit their eggs following mating. I was busy with something else for a few hours and when I returned, the female was busy depositing eggs on her flight cage. I quickly released her to the neighborhood so hopefully she could deposit her remaining eggs at a more suitable location. We are monitoring the eggs now stuck to the top of the flight cage and will be prepared to move the young cats to the backyard buttonbush when they arrive.
Byssus Skipper Problema byssus (Edwards, 1880) P-no. 77a0186, fam. Hesperiidae Host plant(s): Found on eastern gamagrass (Tripsacum dactyloides) Date(s) found: 18 July, 2026 Locations found: Powder Valley Conservation Area, St. Louis County, MO Notes: My first grass skipper cat! Byssus skipper caterpillars spend their time in cylindrical shelters typically made from one grass stem. Look for these in higher quality prairie habitats where their host plants are abundant. Due to loss and degradation of grassland habitat, the byssus skipper and most of the grass skippers are at risk. Although the byssus skipper has a wide range, it is not considered common in any state.
