Do You Have to Gut Load Feeders for Tarantulas?
Gut loading is a common practice in exotic pet husbandry, so it’s only natural if you’re wondering whether or not you need to gut load feeders for tarantulas. This seems to be a particularly common question from people who have a background in keeping reptiles.
It is not necessary to gut load feeders before giving them to tarantulas. Many keepers give crickets directly to their spiders after buying them. However, gut loading won’t adversely affect the spider either, so if you prefer to feed the crickets a nutrient-dense food prior to offering them to your tarantulas there’s nothing wrong with doing so. In fact, many tarantula keepers feel that it is still a beneficial practice.
Why would you gut load feeders for tarantulas?
The idea behind gut loading feeders is that they will make a more nutritious meal item if they are fed properly. This is a carry-over practice from the reptile hobby that was started because reptiles require vitamins and minerals in their diet.
Even though there is no proven benefit for tarantulas, there are many hobbyists that choose to continue doing this because they feel it is better to be safe than sorry. Another common practice is making sure that crickets, roaches, and other feeder insects are offered moisture-heavy foods on the day of feeding. This is because it’s possible that it may help with hydrating the tarantula.
What do you use to gut load feeders for tarantulas?
Many people choose to use high-quality dog or cat foods, as well as a variety of fresh fruits and vegetables to gut load feeder insects prior to offering them to their tarantulas. Carrots are a very common food for crickets and roaches.
There are also premade commercial gut load formulas on the market that you can purchase, however, many people don’t think that these are better than just offering fresh foods. Some keepers will offer their feeders fish flakes and oats in addition to the above-mentioned foods.
Is gut loading beneficial for tarantulas?
There is no conclusive answer to whether or not gut loading feeders will benefit tarantulas like it does reptiles, only anecdotal reports from forum users about their own experiences with feeding (or not feeding) gut-loaded prey.
Little is known about the exact nutritional requirements for inverts, which is why there isn’t a clear-cut answer as to whether or not they get anything out of gut loaded prey items. What we do know collectively as a hobby is that tarantulas have successfully been raised and bred for many years without being offered prey items that have nutritionally dense diets.
I don’t personally go out of my way gut load my feeders prior to offering them to my inverts when I purchase them from the pet store, and it isn’t a practice that I’ve ever made a point to do in all of my years of tarantula keeping.
That being said, I will obviously offer my feeders food if I purchase them in excess and have to keep them in a container for some time prior to feeding them off to my spiders. This usually ends up being fresh veggies or fruit.

Will supplementing my feeder insects with calcium hurt my tarantula?
There is a pervasive myth in the hobby that calcium will cause harm to tarantulas, such as wet molts and other ailments. It started sometime in the early 1990’s, and began circulating after someone had a tarantula die in a molt after being given a mouse. At the time, it was common for new keepers to feed their spiders mice, and if any of them ever ended up having a bad molt they would immediately point the finger at the calcium content.
The specimen that initially started the myth swirling around was likely a wild-caught adult T. blondi, a species which at the time were notorious for dying after import. The bad molt they experienced is highly unlikely to have anything to do with the tarantula being offered a mouse prior to its death. It was more likely due to poor husbandry because Theraphosa are known to be sensitive to mistakes with their care.
Since then, many keepers have perpetuated the story as truth on the basis that there is calcium in a mouse’s skeleton, whereas calcium isn’t found in the exoskeleton of the prey tarantulas usually eat. You’ll see calcium constantly cited as a possible cause for a bad molt when you visit tarantula forums.
You do not need to supplement prey items for tarantulas with calcium, however, feeding them vertebrates like mice and amphibians will also not harm them due to the calcium content. In fact, in the wild T. blondi has been reported to eat a diet high in amphibians by Sam Marshall and Rick C. West, both very respected arachnologists in the tarantula hobby.
A mouse’s teeth and the spider’s propensity to obesity is what will harm a tarantula that is regularly fed mice. This is what Stan Shultz, the author of the Tarantula Keeper’s Guide, has to say in regards to calcium:
“Over the last third of a billion years that vertebrate prey has been available, it requires a huge leap of negative intellect to imagine that arachnids/spiders/tarantulas wouldn’t have evolved an efficient way of dealing with any calcium issues. Or, gone extinct.”
Final Thoughts on Gut Loading Feeders for Tarantulas
In my opinion, sourcing quality feeders is far more important to me than going out of my way to gut load prey items before offering them to my tarantulas. If the feeders have already been taken care of properly before being offered to the spider I just don’t see any reason to fuss with it.
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