The southern region of Arizona is very well-known for being a hot spot for insect diversity, but is also famous for having the one of the highest diversity of moths in the U.S. The reason for this being the many mountain ranges present across southern Arizona, which have been given the name “Sky Islands”. There are miles of open, arid desert land in between each mountain range and it is considered to be like a “sea”, making each range an “island” of biodiversity. Each mountain range has a different diversity of species present within them but for the most part they are packed full of incredible amounts insect diversity. I myself have not been to every “sky island” but I plan to eventually visit them all. As for the moths, they aren’t too difficult to find while blacklighting, you would just need to be in the region during the onset of the monsoonal weather in the mid to late summer.

The entrance to east side of the Chiricahua Mountains near Portal.

Time and Place

There are a number of places to look for moths in the southern region of Arizona. From the Santa Catalina Mountains to the Chiricahuas, there are numerous different canyons, lakes, and trailheads where one can set up a blacklight at night an expect a fair amount of species to appear. The locations aren’t necessarily hard to find or get to, but timing is a very crucial part of whether or not you will be able to see the moths present within each location. From late June to mid or late September, a weather phenomenon occurs in the southwestern United States called the monsoons.

Watching the sunset everyday was a very relaxing experience for me during my time in Arizona.

The monsoons are described as a seasonal change in winds, as well as a change in precipitation. For a majority of the year, winds from the west and northwest are blown into Arizona. During the summer, particularly in June, the southern half of the state becomes extremely hot and dry, which ends up creating a low-pressure system that brings in winds from the south and southeast. This event carries moisture from the Gulf of Mexico, Gulf of California and eastern Pacific and as air is forced upward by different mountain ranges, rain begins to fall. The water from these rain events are reabsorbed into the air during hot days and are blown north, gradually spreading monsoonal rainfall like a blanket into southern Arizona and New Mexico. It because of these events that many tropical species of moths and other insects are found here and nowhere else in the US.

Thunderstorms were a very common sight from where we were in the Santa Ritas.

There are many famous canyons in the southern region of Arizona where collectors and insect enthusiasts go to find moth species of all kinds. Some of the most famous and popular canyons one can visit include Madera Canyon, Box Canyon, Sabino Canyon, Molino Basin, Peña Blanca, Sycamore Canyon, Brown Canyon, Copper Canyon, Garden Canyon, Cave Creek and Pinery Canyon. Blacklighting in these areas can prove to be very fruitful for moths and other insects including beetles, true bugs, and neuropterans. These locations are all very straightforward as far as visitation goes and most, if not all, can be accessed fairly easily.

What to Expect When the Lights Are On

After visiting the southern region of Arizona over the last three years I have been able to see and collect a fair amount of moth species, some more common than others. I have mainly surveyed moths in a number of the canyons throughout the Santa Rita Mountains including Madera Canyon, Florida Canyon, and Box Canyon. When collecting here and in other mountain ranges there are a number of moth species that can be found ranging from large macro moths to very small micro moths. Some of the families of moths one can expect to find include Saturniidae, Sphingidae, Lasiocampidae, Noctuidae, Arctiidae, and Notodontidae. There are plenty more families of moths that can be found in the region but for now I will focus on the ones that are more well-known and easy to spot/identify.

Our blacklight set up near the entrance to the Florida Canyon trailhead proved to be very successful! (Photo Credit: Alex Nguyen)

Of the different families of moths to be found, Sphingidae and Saturniidae include some of the most unique and colorful species known in the southwestern US. Manduca rustica, Manduca florestan and Manduca muscosa are just a few of the many well-known sphinx moths that can be readily found in the Santa Rita Mountains of southern Arizona. Other species include Eumorpha typhon, Eumorpha vitis, Smerinthus saliceti, and Pachysphinx occidentalis, which can also be encountered regularly during the mid to late summer in and around the Santa Ritas. Some species, such as Eumorpha satellitia and Callionima falcifera, have been known to stray into some of the mountains and canyons located in the southern region of the state from Mexico or Central America. I am always hopeful to see species like these that end up straying into the areas I blacklight in because it is as close to the tropics as one can be in the southwest without leaving the country.

This can become a common sight with a mercury vapor light set up in many places across southern Arizona. (Photo Credit: Alex Nguyen)

Saturniidae or silk moths, include some of the largest moth species found in both the US and the world. In southern Arizona and the rest of the southwestern US, there are a number of different species that can be found ranging in sizes, shapes, and colors. Species commonly found in the area I mentioned earlier include, Sphingicampa hubbardi, Sphingicampa montana, and Eacles oslari. Others that are more uncommon in this region but can sometimes be found locally abundant include Anisota oslari, Automeris cecrops, Antheraea oculea, and Eupackardia calleta. There are also a number of day-flying silk moths that can be found in the region, such as Hemileuca heraHemileuca eglanterina, and Coloradia pandora, but they occur during the fall rather than the late summer. Due to the fact that most of the silk moths that come to the blacklight do so at very late hours of the night, they can be somewhat hard to come by. If you are willing to stay up late near the blacklight like I do, then the odds of you seeing these amazing insects is very high.

My colleagues who joined me on the trip to Arizona in 2015 were very excited to see what came to the sheet on the nights that we used the blacklight.

Even though silk moths and sphinx moths are some of the largest moths found in southern Arizona, they are definitely not the most abundant. There are many other groups of moths that make up the rest of the overall moth diversity in the region and a majority of those species are quite small. Despite their small size, they can come in many different shapes and colors and even mimic other insects. As far as collecting goes, I would only advise to be careful with smaller species because they can be damaged much easier than the larger, more robust moths. This region of Arizona has surprised me many times over the past few years and I hope to continue to show others the incredible amount of diversity that is found there.

Patience is the key to finding a majority of moth species while blacklighting.