Sorting and Identifying Moths

Students should not expect to identify all the moths they collect. Moths are currently divided into more than 100 smaller groups (families) compared to only six butterfly families. Consider that there are more than 12,000 moth species in North America and only about 850 butterfly species, yet most people can only expect to identify just some of the common butterflies.

Sorting of the collected moths

To start, moths can be separated from any other insects collected, and the moths then divided into two groups based primarily on size, the smaller micromoths and the larger macromoths. A good rule of thumb is to separate micromoths into anything smaller than 1 to 1.5 cm in wing length.  Beyond these broad groups, students can use their creativity to name “morphospecies” (visually distinct types of moths) that they collect based on size, color, shape, wing edges, and markings such as spots or lines. Various online websites can help students begin to see the diversity of moth shapes and colors to aid in their basic identification. 

Adult moths do not grow in size once they emerge from the cocoon

All growth occurs in the caterpillar stage. Thus, students may be tempted to describe two adults, which are similar in appearance but of distinctly different sizes, as “baby” and “adult” individuals of the same morphospecies. In fact, they are almost certainly two different species of moths and should count towards the diversity of moths under study.

Because of the incredible diversity of moths, identifying them to individual species requires practice and patience in using online resources

Even then, many small or indistinctly colored moths may remain unidentified. Although not knowing a correct identification may be undesirable to some students and teachers, we have found that many students are able to sort unknown moths into different types (“morphospecies”) and enjoy giving them descriptive names of their own. Furthermore, this is another example of authentic science that reinforces the premise that scientists and teachers do not know all the answers (in this case, moth species identifications) ahead of time. We hope teachers will encourage their students to see themselves as researchers who can find (or attempt) the answers through their study. (Be assured that even professional scientists do not know all the names of the insects they collect and must regularly reach out to other experts as needed.)

Moth Identification Resources

For those teachers and students who choose to go deeper into moth identification, some helpful resources are described below. Even with the limitations of each, these online resources can be used to help narrow down the possible identification of your moths. They also provide additional information about moth ecology and geographical distribution that students can use in their research

Seek by iNaturalist

Powered by the same search algorithms in iNaturalist, Seek provides levels of identification without requiring a user account.  It is made especially for student use. Care must be taken as the search does not incorporate size and unless you have a clear picture and distinct coloration patterns, incorrect matches often occur.  

Seek by iNaturalist Website

Discover Life

Uses a pattern key by state or region allowing you to select the size and characteristics of your moths to narrow down a list of possible species.

Discover Life Website

Google Lens

Uses a photograph of your moth to search matching images and provides links to websites. Like Seek above, care must be used as incorrect matches often occur for small and uncommon species.

Google Lens Website

Moth Photographers Group (MPG)

A comprehensive database of almost all moth species in North America with color photos and suggestions on how to identify moths. Because of the vast numbers, it is recommended that MPG be used after you have narrowed down your possibilities using one of the above resources.

MPG Website

Additional resources

The following three resources are popular online communities where photos can be taken/submitted for help in identification, although this can take time. These require creating user accounts which is often not recommended for student users. Because these are user-based, they are good for common species but less so for small and uncommon moths.

Photo Credit: Thanks to students at Grand Blanc East Middle School and Chesaning Middle School