Mexican Free-tailed Bats

The other night we took a friend to see the Mexican Free-tailed Bats at the Congress Street Bridge here in Austin, Texas. This is the largest urban bat colony in the world. It had been a while since I had seen it and reminded me of the great photo opportunities I've had with this species.


The Mexican Free-tailed or sometimes called Brazillian Free-tailed Bat (Tadarida brasiliensis) is a wide-ranging bat found throughout North, Central and South America. They get their name because of their long, prominent tail.


They can roost in a number of different places from buildings to trees, but they are probably best known for the large colonies they form in caves. The photo above was taken at the Eckert James River Bat cave owned by the Nature Conservancy. It is one of the largest bat nursuries in North America and his home to around 4 million bats throughout the summer. The emergences from this cave are quite impressive.




The two photos above were taken at Bracken Cave owned by Bat Conservation International. It is home to the largest bat colony in the world and is home to some 20 million Mexican Free-tailed bats that emerge every night throughout the summer. It is truly a spectacular phenomenon and I encourage anyone  who has the opportunity to watch an emergence. They are so numerous when coming out of the cave that as they fly in a cyclone like pattern up and out of the entrance, some bats get pushed to the outside and are actually impaled on prickly pear cactus spines!

Spring has Sprung

This has been a very dry spring in Texas, but the insect activity is picking up quickly. Here are some of the neat things now flying in the Austin area, specifically at Wild Basin Wilderness Preserve.



This is a snakefly (Agulla sp.); so named because of its cobra like head and appearance. A neat group of insects generally placed in their own order (Raphidioptera), but sometimes placed in the Neuroptera (lacewings, ant lions and owlflies). They are predators and found only in the west within the U.S. Austin, Texas is at the very eastern edge of their range. This is a female with a its long ovipositor that she uses to lay eggs in the crevices of bark and rotting wood.


This is a robber fly in the genus Efferia, most likely E. snowi. Like the snakefly above, this is a predator and a female with a stout ovipositor. Efferia species can be commonly seen perching on rocks and vegetation while waiting for potential prey items to pounce on.


This is a small long horn beetle (Typocerus sinuatus). These can be seen commonly on flowers at Wild Basin right now. They will readily fly from one flower to another looking for mates and taking in nectar.

The Dark of Night

Blacklighting, or the use of an ultraviolet light to attract insects at night is a favorite past time of almost every entomologist. This technique can bring in amazing numbers of insects. The most productive time to blacklight is usually on a calm, balmy night with a new moon and no competing artificial light sources. It is fun to take the time to photograph insects coming into these lights. Because they are nocturnal, many of these are seldom seen.


This is a composite of many moths, beetles, true bugs, caddisflies, and true flies that came to a light I had setup throughout the night.


This Armyworm moth visited the light frequently one night. The larvae can be very destructive on a variety of crops and considered serious pests.


This is not a mosquito, but rather a non-biting midge in the family Chironomidae. They are really neat when seen up close. Like mosquitoes, their larvae are aquatic, but as their name implies, they cannot bite and are harmless.


This is the adult of a net-spinning caddisfly in the family Hydropsychidae. This group of insects have aquatic larvae. The adults look like moths, but they have hairs on their wings rather than scales and they lack the coiled proboscis found in moths and butterflies.


This caddisfly belongs in the family Leptoceridae. They are called Long-horned caddisflies because they have very long antennae.


This is one of my favorite insects, the dobsonfly. The larvae are aquatic, called helgramites, and are often used for fish bait. The adults are short-lived, secretive and thus rarely seen by the casual observer. Males (left) in this group have very long sickle-shaped mandibles that they use to grab a hold of the female (right) with during mating. They are large and really cool looking!

Dragons Underwater

Most people are familiar with dragonflies and damselflies as adults, but few are familiar with the much longer-lived and equally (if not more so) interesting larval stage. They live in the water in a variety of habitats and take on a tremendous variety of shapes and forms. Below are representatives of four different dragonfly families and one damselfly family.


Common Sanddragon (Progomphus obscurus)

Gray Petaltail (Tachopteryx thoreyi)

Yellow-sided Skimmer (Libellula flavida)

Undescribed Spiketail (Cordulegaster sp.)

Ebony Jewelwing (Calopteryx maculata)