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"I Found A Tarantula!"
Miep R. O'Brien
Carlsbad, New Mexico USA

Native USA Tarantulas

There are over 50 species of tarantulas native to the southwestern and central portions of the United States, including several undescribed species (unknown to science). They can be found in all or parts of (going in a circle): California, Arizona, New Mexico, Texas, Louisiana, Arkansas, Missouri, Kansas, Oklahoma, Colorado, Utah, and Nevada. Their eastern border is the Mississippi River and further to the north, the Missouri River. There is an introduced population of Brachypelma vagans in central Florida, but this species is indigenous to southern Mexico and Belize.

People living in these areas often encounter wandering tarantulas at different times of the year. Depending on the species, many have a more or less set mating season which may occur in the spring (e.g., much of central and South Texas), summer (e.g., portions of southern New Mexico and Arizona), or fall (e.g., the high plains of the Texas Panhandle and southeastern Colorado). In desert areas, the mating season is not as clear, and it may depend entirely on rainfall; large numbers of Aphonopelma chalcodes from Arizona are often found wandering immediately after the heavy deluges produced by the summer monsoons. In some years, the entire crop of males may be lost if the rains are absent. The tarantulas observed are usually mature males wandering about in search of the burrows of mature females. Immature and female tarantulas tend to stay in their burrows unless flooded, starved, or driven out by an invader (e.g., Pepsis wasps, rodents, etc.); however, this may be too simple an explanation since Texas tan tarantulas (Aphonopelma anax) appear to migrate readily from burrow to burrow. This behavior is not well understood.

When a male tarantula molts for the final time, he matures, and will usually be darker in color (often black), depending on species. Males also are usually longer and slimmer than females and have much smaller abdomens on average. Mature male tarantulas native to the USA are not long-lived. Even in captivity, their lifespan seems to be less than a year, and some only a few months or less. In nature, the lifespan of male tarantulas may be measured in a matter of weeks, days, hours, or minutes. They have no interest in anything other than finding a mate. They are also, like all tarantulas, HARMLESS to humans and most pets (e.g., dogs and cats). Their venom is of no medical significance, and contrary to popular belief, nobody has ever died from such a bite; most people compare the bite to that of a bee sting and experience no lasting ill-effects other than mild to moderate pain and slight swelling at the site of the bite. Most species are nocturnal, and if one shows up in or around your house, it is just because he is trying to hide out during the day to return to his search at night (or maybe you have female tarantulas living around your house). In South Texas, some males hide out in the low mesquite trees during the daytime hours.

If you do not feel comfortable having tarantulas around, please gently chase the spider into a jar with a paintbrush or other long object with a soft end, and deposit it as far away as you feel comfortable. Remember, these animals are completely beneficial to humans, feeding on cockroaches, crickets, scorpions, and likely mice and other rodents.

Some people find these spiders and decide that they would like to keep them as pets; however, the first thing to do is to determine whether you have a mature male as they do not make particularly good pets. They are short-lived and will wear themselves literally to pieces trying to get away in order to find a female. Fortunately, this is easy to do: first, look at the appendages. Tarantulas have eight legs and two shorter leg-like appendages in front called the pedipalps. In mature males, the pedipalps are swollen with the reproductive organs. In females and immature tarantulas of both sexes, the pedipalps look like small walking legs. Additionally, mature males have little hooks or spurs on the underside of their front pair of legs, at the base of the tibial segment (i.e., the third segment up from the "foot", or the long segment after the short patella, or "knee").

Keeping Female and Immature Tarantulas as Pets

Some people are fortunate, and find wandering females or immature tarantulas in the USA, and though these are also valuable specimens for taxonomic studies and we strongly urge you to consider sending them to Brent, these animals also make fine pets. Their needs are simple and adult females can be extremely long-lived - tarantula keepers sometimes joke that you should make a point of making provisions for them in your will. The cage can be a plastic terrarium from a pet shop, a small aquarium, or even a plastic shoebox (available from discount chain stores and dollar stores). The lid should be secure as these animals are surprisingly strong.

The plastic cages with snap-on slatted plastic tops sold at pet shops are fine, just be careful about picking them up by the handles - if the bottom slips out and the cage drops, your pet may well be killed in the fall. Small aquariums are also good, with a couple of warnings. Window screen is exactly the right grade for tarantulas to get their claws stuck in, and windows screen tops may lead to a climbing tarantula (yes, they can walk up glass) getting stuck and losing a leg and falling. If there are rocks or spiny cactuses under it when it falls, it will likely be killed. Everything in the cage should be relatively soft. Substrate may be as simple as potting soil. Some people like to mix up potting soil, topsoil, and/or peat moss. You can use several inches of substrate if you would like to give the spider an opportunity to burrow (it may or may not). This is an especially good idea with taller cages. The distance from the substrate to the top of the cage doesn't need to be more than eight or ten inches, and a lot more, again, can be dangerous if the spider falls from the inside of the lid.

You should also provide a hiding place, some tarantulas will use them. This can be a clay flower pot cut in half, or a piece of cork bark, or any other soft curved cave-like object. Other than that, all you need is food and water. Watering the substrate and/or misting the tank is not required. A water dish alone is sufficient. This can be a plastic bottle or jar cap and should always be kept full. If the spider hangs around its water dish for long periods of time, it may need higher humidity levels. If this happens, it's time to moisten the substrate a little, but don't go overboard - dampen it, don't get it wet. Do not keep any tarantula where it will be hit by direct sun, this can easily overheat and kill a spider.

Food can be as simple as crickets purchased at a pet shop. You can also use various kinds of wild-caught insects, such as grasshoppers, beetles and moths. Don't use earwigs or chafer beetles. June beetles are okay but they look a lot like chafer beetles, so if you can't tell the difference, don't chance it. Don't use insects from areas that are being sprayed with pesticides. If the insect is acting weird, it may be in the process of dying of pesticide poisoning. Pinky mice are also sometimes accepted, especially by hungry tarantulas. They will also sometimes take dead prey, even little pieces of beef heart. Make sure you clean out the remains quickly as they decay and attract mites (and smell horrible).

When you are working with tarantulas native to your area, temperatures are not something to be concerned about as long as the spider is kept inside your house. Room temperature is fine. Overall temps below 70F may lead to dormant behavior, and above 90F you should be careful with providing the spider with adequate moisture. Their burrows hold soil moisture and help to humidify them during hot dry summers, and high summer temperatures in a more exposed caged environment can be stressful.

Tarantulas molt occasionally. Mature females do this roughly once a year, immatures do so more frequently. They will stop feeding for awhile beforehand, and the abdomen may look shiny and dark, especially if the spider has developed a bald spot on the abdomen. When a tarantula is preparing to molt, it will flip over on its back or side. It is extremely rare for a tarantula to do this for any other reason. Dying spiders generally curl up their legs under them. When your spider flips on its back, do not touch it. It's not a bad idea to mist the surrounding substrate and the spider's legs and cepahlothorax, but don't get water near the booklung openings. Molting is fascinating to watch and usually takes a few hours at most. The spider will be extremely fragile after it molts and should not be disturbed in any way for at least a week, until its new exoskeleton hardens up.

If you wish to find out the sex of your spider, this can be done from the molt. Send it to the American Tarantula Society with your email address and we will be happy to do this for you and email you with the results.

Tarantulas occasionally get injured, and molting as well is an especially hazardous time for them. The ATS Arthropod Medical Manual is available from us for $6 (additional postage internationally) and covers all that is known on how to prevent tarantula injuries, and how to treat them when they occur. The most common medical crises for tarantulas in captivity are injuries from falls and those resulting from the tarantula trying to molt when it is being kept either too dry or too wet. Injuries from falls can be prevented by designing the cage properly. Only arboreals can be safely kept in tall cages. Terrestrial (ground-dwelling, usually burrowing) tarantulas are often much more appreciative of deep soft substrate, in which some will be quite interested in constructing burrows. The space between the lid and the surface of the substrate need only be as long as the tarantula's legspan, or a little more. Terrestrial tarantulas are kept much more safely in cages that are not too tall.

Molting problems include spiders not being able to get fully out of their molt, and this is usually due to their being kept in conditions that are too dry for them. Their need for moisture varies wildly among species. It is crucial to find out what species you have. Some species that prefer dryer conditions and are being kept too wet, may literally fall apart when they attempt to molt, legs falling off and the spider dying from bleeding to death and perhaps fungal or bacterial problems that led to their losing their appendages. This is quite different from a spider getting stuck in its molt and not being able to extricate its legs from the molt.

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