Most pet spiders eat live insects, and the best options depend on your spider’s species and size. Crickets, roaches, and flies are the most commonly used feeder insects, but getting the prey size right matters just as much as the type. Here’s what you need to know to keep your spider well-fed and healthy.
Best Feeder Insects by Spider Type
Spiders are generalist predators, meaning they’ll eat almost any insect that’s the right size. For tarantulas and other ground-dwelling species, crickets and dubia roaches are the go-to options. Both are widely available, easy to keep at home, and nutritious enough for most captive spiders.
Jumping spiders are a different story. Flies, particularly green and blue bottle flies, are one of the most popular and well-accepted food choices. Some jumping spider species strongly prefer flying prey and may flat-out refuse crickets. The canopy jumper (Phidippus otiosus) is one well-known example. If your jumping spider turns its nose up at crickets, try flies before assuming something is wrong. Pinhead crickets (tiny, newly hatched ones) tend to work better than full-sized crickets for smaller jumping spiders, and many will also accept small dubia roaches.
Mealworms and waxworms can work as occasional treats, but they’re higher in fat and have tough outer shells that some spiders struggle with. They shouldn’t be the main diet.
How to Size Prey Correctly
Prey size is one of the most important details new spider keepers get wrong. Research on spider feeding behavior found that prey roughly 50 to 80 percent of the spider’s body length gets the highest acceptance rates. Prey that’s double the spider’s size was refused by nearly all species tested. A good visual shortcut: the feeder insect should be no larger than the spider’s abdomen. If you’re unsure, go smaller. A spider can easily take down something slightly too small, but an oversized cricket left in the enclosure can actually stress or injure your spider, especially during vulnerable periods like molting.
Feeding Frequency for Adults and Spiderlings
Adult tarantulas generally do well eating once or twice a week. Some larger species can go even longer between meals without any health concerns. Spiders in the wild don’t eat on a set schedule, so occasional fasting is normal.
Spiderlings need more frequent feeding to support their rapid growth. One or two appropriately sized crickets or roaches per week is a solid baseline for small slings. The key word is “appropriately sized,” since a spiderling’s prey needs to be tiny. Pinhead crickets, flightless fruit flies, or pre-killed and cut-up insects all work well for very young spiders. As your spider grows through successive molts, you can gradually increase prey size.
Why Your Spider Stopped Eating
If your spider suddenly refuses food, the most likely explanation is premolt. Spiders shed their exoskeleton to grow, and in the days or weeks leading up to a molt, most species stop eating entirely. Several signs point to premolt:
- A fat, shiny abdomen. The abdomen may swell to 1.5 times the size of the front body segment as fluid builds beneath the old exoskeleton.
- Darkened coloring. The new exoskeleton forming underneath causes a visible darkening, especially on the abdomen. Tarantulas with bald patches from flicking defensive hairs show this most clearly.
- Lethargy and hiding. Many spiders become noticeably less active and retreat to their burrows, sometimes sealing the entrance.
- A web mat on the ground. Tarantulas often lay down a flat hammock-like sheet of silk where they’ll flip onto their backs to molt. If you see this, the molt is likely a day or less away.
During premolt, remove any uneaten feeder insects from the enclosure. A live cricket can bite and injure a molting spider. Wait until a few days after the molt is complete and the new exoskeleton has hardened before offering food again.
Gut-Loading: Making Feeder Insects More Nutritious
Feeder insects straight from the pet store aren’t particularly nutritious on their own. Crickets and roaches are naturally low in calcium and certain vitamins. Gut-loading, the practice of feeding your feeder insects a nutrient-rich diet for 24 to 48 hours before offering them to your spider, turns them into better meals. Feed your crickets or roaches fresh vegetables, high-calcium greens, or a commercial gut-loading diet during that window.
Timing matters. Nutrient levels in feeder insects drop quickly once they stop eating the enriched diet, so offer them to your spider within a few hours of gut-loading for the best results. This practice is more established in reptile keeping, but the same logic applies to any insectivore: a well-fed cricket is a more nutritious cricket.
How Spiders Actually Eat
Spiders don’t chew. They digest their food externally, which is worth understanding because it explains some of the odd behavior you’ll see at feeding time. After subduing prey with venom, a spider floods the body with digestive enzymes that liquefy the insect’s tissues from the inside out. Specialized enzymes break down the prey’s exoskeleton while others dissolve soft tissue into a nutrient-rich soup that the spider then sucks up. This process can take hours, so don’t be surprised if your spider sits with its prey for a long time. The leftover husk, called a bolus, is normal. Remove it from the enclosure once your spider walks away from it.
Water and Hydration
Spiders need water, and dehydration is a surprisingly common problem in captivity. How you provide water depends on the species. For tarantulas, a shallow water dish works well. Keep it clean and refilled, and make sure it’s shallow enough that the spider can’t submerge itself.
Jumping spiders are trickier. Their book lungs (breathing organs on the underside of the abdomen) sit close to the ground, making standing water a potential drowning risk. Many keepers mist the enclosure once or twice a day so the spider can drink from water droplets on the walls or web. If you do use a water dish for a jumping spider, keep it very small and place it high in the enclosure. Adding tiny pebbles to the dish gives the spider something to grip and prevents full submersion. Use bottled spring water rather than distilled or tap water, since distilled lacks minerals and tap water may contain chlorine or other additives.
The One Spider That Eats Plants
Nearly all of the roughly 40,000 known spider species are carnivores. The one notable exception is Bagheera kiplingi, a jumping spider found in Central America that feeds primarily on plant tissue. Specifically, it eats protein-rich nubs called Beltian bodies that grow on acacia trees. In Mexican populations, these plant structures made up 91 percent of the spider’s diet, with occasional nectar supplements. Researchers estimate that these spiders get over 95 percent of their nutrition from plant sources, making them near-total vegetarians throughout their lives. This is not something you need to replicate at home. No pet spider species requires or benefits from plant matter in its diet. It’s simply one of the more surprising facts in spider biology.