Can You Feed Crested Geckos Black Soldier Fly Larvae?
By: Jason
Last Updated: February 23, 2023
Insects are part of the natural diet of crested geckos, but not all insects are good for them. What about BSFL? Can crested geckos eat black soldier fly larvae?
Crested geckos can eat black soldier fly larvae (BSFL) as a staple feeder. Black soldier fly larvae are packed with calcium and have a good amount of protein and fat. They are widely available and easy to keep.
There is more to learn about buying and storing BSFL and how to get them ready for your crested gecko. Read on to discover all you need to know!
Species Overview
Black soldier fly larvae (Hermetia illucens) is the larval stage of the black soldier fly. The species is native to the warmer coastal states in the US and Canada and lives on all continents.
Black soldier fly larvae are also known as Phoenix worms, NutriGrubs, ReptiWorms, and CalciWorms. Each is a trademarked brand of BSFL based on diet, packing medium, and testing.
Life cycle
The lifecycle of the black soldier fly has four stages; egg, larval, pupal, and adult.
Adult females lay hundreds of eggs at a time, often near compost or manure. The eggs hatch four days later.
The larval stage naturally lasts between 18-36 days but can be extended by months at ideal temperatures and control over food sources.
At the end of this stage, they enter the pupal stage for 1-2 weeks before becoming adult black flies.
The larval phase is our focus as feeder insects for crested geckos, but the eggs and flies are feeders for other animals.
Diet
Black soldier fly larvae live in compost and get top-tier nutrients as they feed on it. They will eat nearly any type of organic waste. Bits of food, compost, and manure are all on the menu.
Adult flies don’t eat anything, instead relying on stored fat.
Some raised as feeders eat a mix of grains and grasses with extra nutrients. Others use local food scraps to help compost waste and keep it out of landfills.
Other notes
The larvae and adults are not considered pests and don’t carry diseases. Unlike houseflies, adults don’t fly much. They mostly ignore people and stay away from our food.
Black soldier fly larvae don’t bite or have a stinger. They can’t harm you or your pet.
Nutritional Value
It is vital to look closely at the nutritional value of anything you feed to your pet.
Husbandry changes the nutritional composition of an animal. If you look around, you will find a range of results online. Below is an average of their nutrients.
Black Soldier Fly Larvae
- Protein – 17.5%
- Fat – 14%
- Fiber – 3%
- Moisture – 62%
- Minerals – 3.5%
- Calcium – 9256 mg/kg
- Phosphorous – 3560 mg/kg
Black soldier fly larvae have a lot going for them nutritionally.
They are high in protein and fat, but it is their calcium content that causes them to stand out. Unlike other live feeder insects, black soldier fly larvae have an excellent calcium content and a healthy Ca-P ratio. They are the only feeder insect you don’t need to dust.
Compared to other pupae feeder insects, they have a low chitin content, which makes them easier to digest.
Overall, black soldier fly larvae are incredibly nutritious.
Feeding Instructions
Size
Crested geckos can eat insects shorter than the distance between their eyes.
Black soldier fly larvae are among the smaller feeder insects. Newborn larvae start small, about 1/20th of an inch (1 mm). Most grow to 1/2 – 3/4 of an inch long (12-19 mm).
Gut loading
Black soldier fly larvae purchased commercially do not need to be gut-loaded. They do not need any food or water.
(If you feed them, it can reduce how long they last. Giving your BSFL food causes them to defecate in their packing material, which increases humidity and speeds up their growth. They are loaded with nutrients and come ready to go!)
Dusting
There is no need to dust black soldier fly larvae. They are unique among feeder insects because they naturally have a balanced Ca-P ratio.
Where do I feed the BSFL to my crestie?
Like other feeder insects, you have some options on how to feed black soldier fly larvae to your crested gecko.
One approach is to place them in a dry bowl in their tank. As long as there isn’t any moisture in the bowl, the worms won’t be able to climb out. Your crestie can eat them as they like.
A second plan would be to place them in a bowl in a tank intended just for feeding. This secondary enclosure wouldn’t have any substrate to dig in and is only for giving live feeders to your crested gecko. This way, you can keep an eye on the worms and count how many get eaten in 15 minutes. It still has the crestie ‘feeding themself.’
The last option is to hand-feed them with tongs. Pinch the worm with the long pincers and hold it near the mouth of the crested gecko.
Since the larvae wriggle but don’t move about much, this feeder doesn’t stimulate the hunting instinct like some other insects. In that way, hand-feeding doesn’t detract as much as it might with other live feeders.
Give the BSFL time to warm up to room temperature if you keep them in colder conditions.
How often can I serve them?
Insects are a once-a-week food.
Ideally, your pet should mostly eat CGD with some live feeder insects and occasional fruit. This mix gives them all the vitamins and minerals they need.
Many keepers use black soldier fly larvae to feed their crestie for one week and use a different live feeder the following week. Some brands of BSFL are very high in calcium, higher than the recommended ratio. Others are higher in fat than are healthy for a staple feeder.
Serving a variety of foods is vital to optimal pet health.
How many should I give?
You want to feed as many worms as your crested gecko can eat in fifteen minutes.
The size of your pet and the size of the worms will make a real difference in the count. Black soldier fly larvae are smaller than many other feeder insects, so this might be quite a few.
For hatchlings (0-4 months old), start with 2-5 1/4-inch (6 mm) long BSFL. Juveniles (4-12 months old) can likely eat 5-10 1/2-inch (12 mm) long BSFL. Adults (12+ months) might eat as many as 5-10 3/4-inch long (19 mm) worms.
Each animal is different. If you note how many worms your pet eats in one week, you can use that as a starting place for the next time you feed them BSFL.
Dead or alive?
Most crested geckos prefer eating live feeders over dead, freeze-dried, or canned ones.
Canned and freeze-dried black soldier fly larvae are available. They are easy to store, keep for a long time, and help keepers looking to avoid live insects (like, for a pet sitter). But, they are more expensive (per worm), and not all crested geckos will eat them.
There are good reasons to serve dead black soldier fly larvae, but try to use live ones when you can.
Buying & Storing
Price range
So, how expensive are black soldier fly larvae? The answer depends on which brand you choose and how many you buy.
Prices range from 1.5 – 5 cents per worm. You can buy the grubs in different sizes and quantities, and the price goes down when you buy more worms at one time. Some vendors charge the same amount per worm regardless of size, while others increase the cost as they get larger.
The big chain pet stores do not carry live black soldier fly larvae, but many online retailers do. Some include shipping costs in their price, while others do not.
Comparing black soldier fly larvae prices to other feeder insects is tricky. While the ‘price per insect’ for BFSL is only a few cents, you often have to feed a pet many more of these worms than another insect to fill them up.
Where can I buy the best BSFL?
Several great companies sell black soldier fly larvae, often using different brand names.
How do I keep them?
Black soldier fly larvae require little care. Store them in the cup they arrive in with the lid on them.
These worms are packed in a media that looks like sawdust. It’s not their food. The material varies by brand, but they all provide a safe substrate to keep the larvae in until you feed them to your crested gecko.
Keep them at room temperature if you will use all of them within 2-3 weeks. To extend the shelf life beyond two weeks, you can store them between 50 and 55 degrees Fahrenheit. Most people use a cool room in their house, like a basement, garage, or enclosed porch. Some people put them in the door of the refrigerator, but it is hard to keep the temp from dropping too low. Many wine coolers have a manual way to set how cold it gets, which works better.
If you store them in a cool place, give them time to warm to room temp before serving them to your crested gecko.
These critters do not require any food from you. Giving them food may shorten how long they stay in the larval stage. How? An increase in humidity plus their waste matter causes them to grow more quickly. They are perfectly healthy for your pet to eat “as-is.”
How long do they live?
At room temperature, expect black soldier fly larvae to last 2-3 weeks. Stored at the proper, cool temperature, BSFL can last for months.
The optimal temperature to extend their life for the longest is 50-55 degrees Fahrenheit. If they get too cold, however, they will die.
Do All Crested Geckos Like Black Soldier Fly Larvae?
Just like with humans, each crested gecko has preferences. Not every person enjoys the same foods, nor does every crestie.
Can you think back to a time you tried a new food? Maybe you took only a little taste but didn’t love it and then tried more another time. Just like humans, crested geckos need to warm up to new things.
If you’ve offered black soldier fly larvae to your pet and they weren’t interested the first time, don’t worry. Try offering only a few at first, maybe with tongs, to get them started.
Conclusion
Black soldier fly larvae are one of the top live feeder insects for crested geckos.
They are nutritional, with the right amount of calcium. Their protein, fat, and chitin content make them better than a treat.
One of their strengths is that they are easy to keep. Store them in the container they arrived in. You don’t need to feed them or dust them.
Another is that they are inexpensive and they can last a long time.
Overall, BSFL works well as live feeders for crested geckos.
What about other insects? Can Crested Geckos Eat Crickets?