Mating Moths

I've made A LOT of observations on iNat over the last 3 years. So it's not surprising that some of the creatures I have photographed happened to be in the act of mating.

Not to be perverse, but I am always happy when I come across this for a variety of reasons. One reason is that it provides an opportunity to see sexual dimorphism in plain sight since you know you are looking at a male and a female. It is easy to discern different sizes and coloration between the two genders when they are literally attached to one another.

Fall Webworm Moths (Hyphantria cunea) mating

This spring I noticed a lot of variability in the extent of black dots on Fall Webworm Moths and after I saw a couple mating I suspect that maybe sexual dimorphism is the reason. The male has more black dots than the female. I know because after this interaction the female laid her eggs.

Dimorphic Snout Moths (Hypena bijugalis) mating
- observed by Rick Parker.

Garden Webworms (Achyra rantalis) mating.

The Dimorphic Snout lives up to its name: the female has strongly contrasting colors, while the male is mostly brown (two above). Garden Webworms also have some color differences between male and female (above). And there is definitely a size difference between the male and female Waterlily Leafcutter Moths (below), while the Deadwood Borer male and female look much more similar (two below).

Waterlily Leafcutter Moths (Elophila obliteralis) mating

Deadwood Borer Moths (Scolecocampa liburna) mating - observed by Rick Parker (

What else can we learn when we observe creatures copulating? Well, we learn a little bit about their breeding cycle. When they are breeding tells us when their most productive season of the year is - when their food is most readily available. Most birds breed in the spring in time that their eggs will hatch when their primary food source (be it earthworms, caterpillars of our beloved moths, or crawdads) are plentiful. For moths, the food source is going to be various species of plants. A moth that is found mating in early Spring or late Fall must feed on vegetation with a long growing season or could be a generalist - a species that isn't too picky about what it eats.

Clemens' Grass Tubeworms (Acrolophus popeanella) are absolutely thick this time of year (August and early September). Leah (@leahn19) and Rick (@rdparker) have both found pairs mating recently. According to bugguide, as larva this species feeds on the roots of Red Clover (Trifolium pratense). I'm guessing they feed on more than that since we find so many of these in our residential neighborhoods and there isn't any red clover growing in this area. Maybe they also feed on White Clover (Trifolium repens)?

Forest Tent Caterpillar Moths (Malacosoma disstria) mating

I've also learned a little about the speed of the life cycle of a few species of moths. I found a cocoon of a Forest Tent Caterpillar back in April and kept it in a jar until the moth eclosed. I was lucky enough to see the moth leaving the cocoon on May 24. I released the moth outdoors on the patio and just a few hours later a male moth flew in and they were mating (as seen above). Wow - that's quick! Once the mating was complete, the male's purpose was fulfilled. Once the female laid her eggs, her purpose was fulfilled. I wouldn't be surprised if they both expired shortly afterwards. Some species have very short lives as adult moths, with much longer phases as larva and pupa.

Grateful Midgets (Elaphria grata) mating - observed by Rick

The Evergreen Bagworm Moth, has a fascinating life cycle. I'm going to detail that in a future post, but will go ahead and tease you with this photo from Rick.

Evergreen Bagworm Moths (Thyridopteryx ephemeraeformis) mating

I've taken to adding a tag "makin-babies" for all of my observations of mating in process. I have a total of 36 of these observations now, all of which are insects except for a pair of snakes. Maybe I should have used the tag "insex" instead. ;) While the "makin-babies" tag is kind of fun, the tag is really just a way for me to personally find those observations quickly and doesn't serve a greater purpose. What is more useful to the iNaturalist community in general is to use the Observations Fields feature of iNaturalist. When you open an observation in the webpage you will see a section on the right side of the page that says "Observation Fields." If you start typing in that box you will see a wealth of options. There are a lot of fields with the same meaning, which is a little unfortunate, but since anyone in the community can create fields that is how it is for now. The field I have been selecting is "Behavior: mating" and then selecting "yes." I would encourage you to use this same feature anytime you happen to catch some moths (or anything else) in the act!

Bluegrass Webworm Moths (Parapediasia teterrellus) mating

Southern Emerald Moths (Synchlora frondaria) mating

Finally, I'd like to feature three observations of mating moths contributed by other iNatters. Thanks to Sunshine Bush, Shaun Michael, and anhe for these observations!

Meal Moths (Pyralis farinalis) and Boxwood Leaftier Moths (Galasa nigrinodis) mating

Luna Moths (Parapediasia teterrellus) mating

Posted by zdufran zdufran, September 05, 2019 16:02



Nice set, thank you!)

Posted by kildor about 1 month ago (Flag)

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