WGNSS Field Trips – A Thousand Acres of Silphiums

2026 Caterpillar Season – Fall Webworm Moth

2026 Caterpillar Season, Caterpillars of Tyson Research Center, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.

Black-headed phase of Hyphantria cunea.

Red-headed phase of Hyphantria cunea.

2026 Caterpillar Season – Dimorphic Macalla

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

Dimorphic Macalla
Epipaschia superatalis (Clemens, 1860), fam. Pyralidae, P-no. 80a0619
Host plants: In Missouri, this species’ sole host is poison ivy (Toxicodendron radicans). It has also been recorded hosting on poison sumac (T. vernix) and may likely utilize other Toxicodendron species.
Date found(s): June 28, 2026
Location(s) found: Pinewoods Lake Recreation Area, Carter County, MO
Notes: This distinctive caterpillar is most often found in leaf folds of its creation among poison ivy leaves. The “dimorphic” in its common name refers to the two distinct color morphs of the adult moths. The green form has gorgeous mint-green forewings contrasted by a deep chocolate brown, while the tan form has straw-colored forewings but keep the same chocolate-brown lower half.

2026 Caterpillar Season – The Slugs

wildlife, macro, wildlife photography, WGNSS Field Trips, insects, Lepidoptera, Caterpillars of Tyson Research Center, 2026 Caterpillar Season

I do not believe I have shared a single slug moth (fam. Limacodidae) caterpillar in 2026. This is mainly because I shared so many of these in the past several years. I did, however, photograph a few this year and I thought I would pool them all in this one post.

First up is the saddleback caterpillar (Acharia stimulea).
The little ones, which are likely 1st instars, were found at Don Robinson State Park in Jefferson County, while the more developed individual was found at the WGNSS trip to Logger’s Lake in Shannon County. Note in the photo on the right that the little ones do not consume the whole leaf, but at this small stage, they scrape the upper layer of the leaf surface.

Next up is the yellow-shouldered slug moth (Lithacodes fasciola).
The healthy final instar individual was found in Ste. Genevieve County in August, while the poor victim of braconid parasitoid wasps was found at Tyson Research Center in early July.

This shagreened slug moth (Apoda biguttata) caterpillar can often be confused with the species before and after. Notice the shagreen-leather-like texture of the integument to discern this one from the yellow-shouldered slug and the following species. This one was found at Don Robinson State Park in mid-September.

The yellow-collared slug moth (Apoda y-inversum) can be identified by the yellow collar at the anterior end along with the yellow sub-dorsal striping. This one was found at Tyson Research Center in early July.

I had a lot of luck finding the crowd-favorite spun glass slug moth (Isochaetes beutenmuelleri) this season. This one was found in Ste Genevieve County in early August on hackberry.

I typically don’t have much luck finding the smaller parasa (Parasa chloris) caterpillars, but this season we discovered five. The two pictured here were found on honey locust and pin oak. Most limacodids are notorious as being highly polyphagous and can be expected on nearly any woody plant species in the state. This year, I found one of this species feeding on the herbaceous wingstem (Verbesina alternifolia).

This beautiful purple-crested slug moth (Adoneta spinuloides) was found at Tyson Research Center in late July.

The spiny oak slug (Euclea delphinii) is typically, but not always found feeding on oaks. This year, however, we found one using Roseshell Azalea (Rhododendron prinophyllum) as host.

Last but not least is this wonderful skiff moth (Prolimacodes badia). These guys come in a wide assortment of patterns, ranging from mostly green, to what you see here, an animal dressed as a scenescent and diseased leaf. This one was found on the WGNSS trip to Logger’s Lake in mid-August.

This covers the slug moth caterpillars I photographed in 2026. One odd thing to note is that no monkey slug cats were found this year. I’m still trying to wrap my ahead around limacodid abundance and dispersal. Some years, certain species are found in large numbers across a variety of habitat types, while the next year they are difficult or impossible to find. These swings are most likely due to parasitoid pressures that wax and wane and are effective biological controls for all lepidopterans.

2026 Caterpillar Season – False Boneset Flower Moth

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

False Boneset Flower Moth
Schinia grandimedia (Hardwick, 1996), fam. Noctuidae, P-no. 932095
Host plants: Hosts solely on false boneset (Brickellia eupatorioides).
Date found(s): September 12, 2026
Location(s) found: Don Robinson State Park, Jefferson County, MO
Notes: The false boneset flower moth was described in 1996, most likely due to the similarity of the adult moth to a close relative, the three-lined flower moth (Schinia trifascia). Thankfully, the caterpillars are easily distinguished between the two. Like many of the Schinia, the caterpillars of S. grandimedia feed only on flowers and developing seeds of its host and will almost always be found by looking for them on these tissues.

This species is more common in the great plains and has only a few records from Missouri. This one was found at Don Robinson State Park during a WGNSS caterpillar hunting trip.

2026 Caterpillar Season – Goatweed Leafwing

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.

2026 Caterpillar Season – Brown-hooded Owlet

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.

2026 Caterpillar Season – Fawn Sphinx

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.

2026 Caterpillar Season – Black-etched Prominent

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.

2026 Caterpillar Season – Green Leuconycta

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.”

2026 Caterpillar Season – Black-waved Flannel Moth

2026 Caterpillar Season, insects, Lepidoptera, macro, WGNSS Field Trips, wildlife, wildlife photography

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.