Fireflies in Houston
by Donald Ray Burger
Attorney at Law

My goal is simple: to bring fireflies back to Houston! And I am hopeful that the basic principles needed to accomplish this have already been outlined by the butterfly gardeners.

When butterfly aficionados noted the diminished numbers of butterflies they set about discovering how to reverse that trend. And in books and TV shows, and at museums and in gardens, they put forth their message: the number of butterflies is directly related to the presence of suitable habitat.

Butterfly gardeners set about educating the public about such things as (1) the kinds of nectar plants butterflies need; (2) the host plants caterpillars need as their food supply; and (3) problems pesticides pose. I am hopeful that these valuable lessons can be applied to bring back the fireflies.

So why aren't there fireflies in Houston? Theories that have been advanced include: (1) mosquito spray programs; (2) too much light in the city at night; (3) wrong temperatures (too hot or too cold); (4) fire ants kill them, (5) lack of food supply for the larval form of fireflies; or (6) something else.

Spray Programs

Since mosquito control programs don't seem to be able to eliminate mosquitoes and because it is difficult to think of other insects that have been eliminated by spray programs, my conclusion is that although spray programs can hurt a population of insects susceptible to the particular chemicals used, the complete absence of fireflies in Houston cannot be explained by this theory. Also, readers report the presence of fireflies even in cities with spray programs. Nonetheless, insecticides cannot be beneficial to fireflies, and anyone wanting to help reintroduce fireflies would be well advised to avoid insecticides as much as possible.

City Lights

This theory is harder to get a handle on. I have come across no literature addressing the idea that fireflies have light preferences. However, since the blinking lights are the mating signals of fireflies, it makes sense that they would prefer areas where the light is readily visible. That sounds like dark areas. I originally figured that if one found fireflies in other major metropolitan areas this theory would be laid to rest. To that end, I welcomed reader input. And many readers sent me their reports (you can view them by clicking here.) I would still appreciate more reports (send the locations at which you have recently seen fireflies (name of the city, town or rural area), the numbers seen (i.e. a few, quite a few or massive numbers) and what time of the year they were seen (season or date)), but reader input already seen has put this theory to rest. Fireflies are seen in urban areas, and in well lighted ones. Apparently pitch dark is not a necessary backdrop for the mating ritual.

Wrong Temperature

We know that certain plants and animals have temperature preferences. Almost all plant books address USDA climate zones for hardiness. Similarly, we rarely see hummingbirds in Houston except in spring and fall because of their migratory habits. Certain butterflies also migrate through Houston. Do fireflies migrate? I have found no literature on this. Do fireflies avoid Houston because it is too hot--or too humid? The visitor register indicates that Houston's temperature is not a problem, because there are no trends that I can detect as to temperature preferences of fireflies (other than they don't like extreme cold--a condition not usually found in Houston).

Fire Ants

Ah, yes. Another reason to hate fire ants. The theory is that the little beasts eat the larval form of the fireflies, thus interrupting the life cycle. There is some logic to this idea because the fireflies hatch in the ground, and could therefore be at risk from marauding fire ants. But the theory does not hold up to the facts we know. If fire ants were the cause of the disappearance of fireflies we would expect to see no reports of fireflies in areas where fire ants flourish. However, there are numerous reports of fireflies in southern climes where fire ants are also abundant.

Habitat

We now turn to habitat. Butterfly gardeners have paved the way here. They have learned that to increase the presence of butterflies in your garden you must make the garden an attractive site to the particular kind of butterfly in which you are interested. For instance, adult swallowtails (and lots of others) like the nectar of butterfly weed. But if you really want to keep them around your yard you will have to provide plants such as butterfly bush on which the butterflies will lay their eggs so the newly hatched caterpillars will have a ready food source when they hatch. Caterpillars don't eat the same plants as adults and a garden lacking food for the larval stage is an incomplete habitat--and one which will have a lower number of butterflies. The problem is that we don't know what fireflies like to eat. That makes it difficult to create a proper habitat. Still, I personally believe that habitat is the key to reintroduction of fireflies to Houston. We just need more knowledge of what habitat the fireflies need. What we can guess so far is that fireflies like dark, moist soil areas, with tall grasses and decomposing tree branches. Water features such as ponds also seem attractive to fireflies. Not much to go on, but it is a start. Some reports note that fireflies tend to return to the same area each year, so once you have attracted them, they may be there to stay if you provide them with a suitable habitat.

Is Something Else at Work?

If you have a theory not covered above, let me know. The goal here is to gather enough information to solve the problem of the missing fireflies. Any assistance will be appreciated.

To learn more about fireflies, try some of the topics on the left. Thanks for visiting. Comments are always welcome.