Attracting Moths and Their Unexpected Predators

**A harvestman (*Leiobunum* sp.), an arachnid, has captured and killed a horned spanworm moth (*Nematocampa resistaria*).**

Attracting moths at night using lights has yielded an amazing number of species that I never even dreamed existed. My last count was at 865 moth species with 34 new species added to the checklist this year alone.

Many other insects, besides moths, come out at night to my lights. These include beetles, flies, Hymenoptera, and typical bugs. There are also leafhoppers, mayflies, caddisflies, Neuroptera, arachnids, myriapods, and Collembola. During the warmer, humid months of summer, there can be a lot of insect activity at the moth light.

People who put out bird feeders are often horrified when a shrike or hawk comes swooping in and takes away a chickadee. Those birds must eat, but that is not why we put out feeders. At night, attracting moths can pose similar problems with spiders, ants, and frogs drawn in by all the insect activity. Snakes then follow, hunting the frogs.

Here I present some photos of various predators that have come to my moth light. They include harvestmen, spiders, lacewings, ants, and frogs observed preying upon moths and other insects attracted to my moth light. The worst instance of predation, from my perspective, involved a fishing spider (Dolomedes tenebrosus). It captured and ate a twin-spotted sphinx (Smerinthus jamaicensis). I was upset, but it was too late for the moth. The spider’s venom acts quickly, and there was no saving it.

Arachnids: spiders and harvestmen

In the top photo is a harvestman (Leiobunum sp.), an arachnid, that has captured and killed a horned spanworm moth (Nematocampa resistaria). I have no idea how it accomplished this. They have no venom glands. They also lack sticky silk threads to snare prey like their spider relatives. Harvestmen are ambush hunters, but this is a large moth compared to the harvestman. Did it poison the moth using secretions from its scent glands (ozopores)? Does it use those secretions to secure prey, not just to deter enemies? All sources I have checked say no, but maybe this is something waiting to be discovered.

I should add that not all the harvestmen who come to the mothing light eat insects. One evening, I left out peels from very ripe bananas. I hoped the aldehydes and other volatiles would attract certain kinds of moths. That didn’t work, but I did see a harvestman consuming some of the pulp left on the skin. I wonder if it got its five servings a day of fruit?

Above is a fishing spider (Dolomedes tenebrosus) that has captured and is eating a northern gluphisia moth (Gluphisia septentrionis). The same spider appeared the next evening and captured another northern gluphisia.

**A female *Araneus bicentenarius* (lichen orb weaver spider) in the center of her web near the moth light.**

Some spiders, like this lichen orbweaver (Araneus bicentenarius) above, build webs near the moth light. They do this probably because the corner of the porch wall offers a convenient trapping location. My moth light unintentionally lures moths and other insects near the orb web, where they can be trapped.

This spider didn’t stay long for some reason, and no insects were trapped. It may have been because a pair of eastern phoebes (Sayornis phoebe) were nesting in a little nook overhead. They may have created too much disturbance, or even eaten the spider. In any event, the spider was gone after one day. Phoebes do eat moths and I have seen them capturing moths that remained on the porch wall after sunrise.

Hymenoptera: ants

*Crematogaster* sp. (acrobat ants) have captured a small caddisfly.

Ants are active during the day and also at night. This is not surprising as they spend a good part of their lives in dark tunnels, finding their way using scent trails laid down by other ants. Above, a swarm of Crematogaster sp. (acrobat ants) has captured and is dismantling a tiny caddisfly that got tangled in spider web fragments.

Neuroptera: lacewings

**A green lacewing (*Chrysoperla* sp.) is searching in the debris of spider web fragments for prey.**

Lacewings eat aphids and other small soft-bodied arthropod prey, including insect eggs. This lacewing (Chrysoperla sp.) was searching in spider web fragments where small leaf hoppers, like Chlorotettix spp. and psyllids, became entangled. When the lacewing found one, it ate it.

Amphibians: frogs

A gray tree frog (*Hyla versicolor*) is getting ready to strike at a **psyllid**, **an aphid-like insect.**

Finally, a gray (okay, this one is green) tree frog (Hyla versicolor) on the hunt, searching for minute insects like this psyllid drawn to the moth light. Gray tree frogs are frequent visitors to the moth light, searching for food. With their sticky foot pads, they can climb up the walls to hunt for prey. Most of the gray tree frogs are small young-of-the-year individuals, but sometimes larger adults show up.

Spring peepers (Pseudacris crucifer) are common visitors. Like the gray tree frogs, many are young-of-the-year.

*Pseudacris crucifer* (Spring Peeper) froglet on the wall by my moth light, looking for small insects.

Down below on the ground, American toads (Anaxyrus americanus) search for fallen insects. Green frogs (Lithobates clamitans), mink frogs (Lithobates septentrionalis), and wood frogs (Lithobates sylvaticus) also look for insects that may be on the ground or under the porch. Some green frogs and mink frogs took up residence on the porch, living in pans where I was growing duckweed and other floating aquatics. Garter snakes (Thamnophis sirtalis) occasionally come by, too, and prey upon the terrestrial amphibians.

Another gray tree frog, this one boldly patterned, is preparing to climb up the wall in search of insects. This same frog would also climb up the glass of my office window at night to eat insects attracted to the light shining through the glass.

Some final thoughts

So, do you do mothing? And if you do, have you seen spiders or other predators coming by in search of food? What did you think about that? Should these predators be chased away?

Essential Guide to Midwest True Bugs by Angella Moorehouse

This just arrived today, and I know it will be so very useful as I venture further into the world of insects. Flower Bugs: A Field Guide to Flower-Associated True Bugs of the Midwest by Angella Moorehouse (2023) is published by Pollination Press LLC, Minnetonka, MN. The Pollination Press web address is www.pollinationpress.com.

This book has 360 pages, lavishly illustrated with beautiful full-color photographs of 160 species of terrestrial true bugs from 25 families and 52 genera. The area covered includes the states of Minnesota, Iowa, Missouri, Wisconsin, Illinois, Indiana, Ohio, and Michigan in the US and Southern Ontario in Canada.

The book includes taxonomic charts that will guide you to family and then to genus, detailed illustrations of bug morphology, their ecology, and a glossary of terms to help you learn and identify true bugs.

Species descriptions are not overly technical, thus making this book more accessible to non-specialists with some background in insect identification. Maps show the range of each species. There are notes on key identifying features, life history, ecology, feeding, and habitat. Descriptions of herbivorous species include lists of plants they consume. Carnivorous species are similarly treated. Not all species receive the same description treatments. Some are represented with photographs.

There seems to be a problem with the index, where some entries do not match the page numbers in the book. Not sure why.

I am loving this book already and will put it to good use identifying the many bug species I have photographed. My first project will be to go through the unidentified species in my files and to re-check previous identifications. After that, I’ll spend many an evening just browsing and waiting for spring and the bugs to return.

Discovering the Red-streaked Mompha, a beautiful tiny moth

*Mompha eloisella* was probably attracted to the many *Oenothera biennis* plants nearby.

This is Mompha eloisella (Red-streaked Mompha), a tiny moth with beautiful satiny white wings speckled with symmetrically placed dark brown spots on the head, thorax, and wings, and red diagonal lines on the wing tips. The patterning of the wing tips resembles a face, but who or what will notice something that small and possibly be deterred by it? Or maybe that’s what the markings are for at all.

Mompha eloisella is in the family Momphidae, which worldwide contains at least 115 species. In North America, there are 45 species just in the genus Mompha and probably many more yet to be discovered and described. All are tiny and have unique patterns, often colorful, on their wings. The larvae of most Mompha species feed on plants in the Onagraceae (evening primrose family) as stem, flower, or fruit borers or as leaf miners. Mompha eloisella larvae are stem borers in evening primrose (Oenothera spp.). This one may have been attracted to the small stand of Oenothera biennis growing in my garden.

Mompha eloisella is widespread in the US, but available range maps show it as not present in Minnesota. Now we know it does occur in Minnesota, with this first sighting more than 120 miles north of a previous sighting in Wisconsin.

This isn’t the first Mompha moth I’ve seen here. There are four other species, all very tiny and beautifully patterned. The small size of these moths makes them easy to miss and difficult to photograph, but with a little effort and patience, they can be found and sometimes photographed clearly. Of course, not all of my Mompha photos are clear, but clear enough. They seem skittish, which also makes photographing them a challenge.

To attract more Mompha moths, I have planted Oenothera biennis, Epilobium angustifolium (fireweed), and let the weedy annual Epilobium coloratum (willow-herb) have a place in my flower garden. Not only are these plants food for Mompha moth larvae, but their flowers, sweet with nectar, are food sources for bees, small and large, and even hummingbirds. After blooming, the plants continue to benefit wildlife. A few days ago, I saw an eastern goldfinch in my flower garden feeding on the small seeds of evening primrose.

References and sources:

Genus Mompha https://bugguide.net/node/view/41654

Species Mompha eloisella – Red-streaked Mompha – Hodges#1443 https://bugguide.net/node/view/67246

Mompha eloisella (Clemens, 1860) http://mothphotographersgroup.msstate.edu/species.php?hodges=1443

A more technical description of this Mompha species, and several others, can be found at the Moths of North Carolina website.

For the birds

Dogwood berries for wildlife — ***Pagoda dogwood (Cornus alternifolia) fruit which is favored by catbirds and vireos among others.***

The birds are preparing for their annual fall migration. With the long journey ahead of them they will need plenty of food resources high in calories and protein. Bird feeding stations with plenty of sunflower seeds are one source of high energy/high protein foods but there are other sources and they literally grow on trees.

By late August where I live most of the soft and juicy fruits like raspberry (Rubus strigosus), blackberry (R. allegheniensis), and blueberry (Vaccinium myrtilloides and V. angustifolium) are done although there are still some dewberries (R. pubescens) and creeping blackberries (R. setosus) in the woods. At this time arrow-woods (Viburnum dentatum and V. rafinesquianum), Canada elderberry (Sambucus canadensis), bunchberry (Cornus canadensis), and pagoda dogwood (Cornus alternifolia) are coming into fruit.

Many fruits are sweet with sugars but some are rich in fats or lipids. Avocados and olives are familiar examples. Studies on dark fruited viburnums have found that they are rich in lipids. By dry weight southern arrow-wood (Viburnum dentatum) is 41.3% fats (that’s a lot of energy) and 2.6% protein. These numbers are similar in some but not all dark-fruited viburnums. Lipid content is correlated with seed shape and pigmentation. Blue fruits with round seeds have higher lipid content. Black fruits with flat seeds have lower lipid contents. Red fruits with flat seeds are low in lipids while red fruits with round seeds have a bit more. The lipids produce the blue iridescence in the fruit which is attractive to birds and are a nice benefit for hungry birds.

Southern arrow-wood does well in moderately fertile soils that do not dry out too rapidly. Mine receive full sun for about eight hours a day.

***Southern arrow-wood (Viburnum dentatum)*** **laden with fruit.**

Does the dark-colored fruit of pagoda dogwood (Cornus alternifolia, shown at the top of the page) have a high lipid content? So far I have not found any information on the fruits themselves although some species of dogwood have lipid-rich seeds. I’ve observed evening grosbeaks eating the seeds. Pagoda dogwood is a small tree-like species common in the understory of hardwood forests with rich soil and small enough for a garden.

Canadian elderberry (Sambucus canadensis) bushes growing near my house are beginning to mature fruit. I’ve never been able to eat more than a few elderberries in all the years it has been here as the birds eat the fruit as soon as it ripens. Its red-fruited relative called red elderberry (S. pubens) blooms earlier in April and matures thick clusters of soft red berries that are eaten by robins and catbirds. Both elderberry species thrive in rich most soil near the edges of forested areas.

Elderberries for wildlife — **Canadian elderberry (Sambucus canadensis)**

The arrow-wood, pagoda dogwood, and elderberry fruits will soon be gone usually by September 10th. But some other fruiting trees and shrubs will be ripe around that time. These include gray dogwood (Cornus racemosa), nannyberry (Viburnum lentago), hawthorns (Crataegus spp.), and mountain ash (Sorbus spp,). These shrubs will do well in any rich moist soil in full sun to partial shade.

To help out birds that remain in the winter I have planted small-fruited crabapple trees in different places. Robins, ruffed grouse, and sometimes pileated woodpeckers will eat the smaller fruited crab apples like Malus sargentii while blue jays and other birds go after the larger fruited varieties like Dolgo Crab or any feral apple for that matter. The fruits become softer after a few freezes and in years of heavy fruit set some apples will remain on the trees as late as March.

Other fruit-bearing shrubs with winter persistent fruit are highbush cranberry (Viburnum opulus var. americanum) and winterberry (Ilex verticillata). When first ripe the fruits on these bushes are not eaten by birds but after freezing and thawing some birds will eat them. Highbush cranberry and winterberry prefer rich moist soils and can be found naturally in wetlands. They will do well, though, in any good garden soil in full sun to part shade.

Wild sunflowers and weeds like pigweed are also food sources for migrating birds and I’ll be covering these in a future post.

SOURCES

Fruit Quality and Consumption by Songbirds During Autumnal Migration (Susan B. Smith, Kathleen H. McPherson, Jeffrey M. Backer, Barbara J. Pierce, David W. Podlesak, and Scott R. McWilliams). The Wilson Journal of Ornithology 119(3):419–428, 2007.

Viburnum tinus Fruits Use Lipids to Produce Metallic Blue Structural Color (Rox Middleton, Miranda Sinnott-Armstrong, Yu Ogawa,Gianni Jacucci, Edwige Moyroud, Paula J.Rudall, Chrissie Prychid, Maria Conejero, Beverley J.Glover, Michael J.Donoghue, Silvia Vignolini). Current Biology. Volume 30, Issue 19, 5 October 2020, Pages 3804-3810.e2

Fruit Coloration: Attractive, Fatty Blue Colours? (Bodo D. Wilt). Current Biology. Volume 30, Issue 19, PR1078-R1080, October 05, 2020.

Fatty Acid Composition of Cornelian Cherry (Cornus mas L.) (Agata Antoniewska, Jan Brindza, Svitlana Klymenko, Olga Shelepova). 5th International Scientific Conference Agrobiodiversity for Improving the Nutrition, Health, Quality of Life and Spiritual Human Development, Nitra, Slovakia. November 2021.