Feeder Insects

Feeder insects form the dietary foundation for most carnivorous invertebrates kept in captivity, from tarantulas and scorpions to mantises and assassin bugs. When you are keeping predatory species, the quality and variety of your feeder insects directly determines the health and longevity of your animals. Think of feeders not as simple food items but as nutritional delivery systems that transfer whatever they have eaten and absorbed into your invertebrates. The cricket or roach you offer tonight becomes the building blocks for your tarantula's next molt or your mantis's developing eggs.

The world of feeder insects includes crickets, roaches, mealworms, superworms, waxworms, fruit flies, and many others. Each type brings different nutritional profiles, different movement patterns that trigger feeding responses, and different challenges for maintenance and storage. Matching the right feeder to your specific invertebrate species matters tremendously because what works perfectly for a large tarantula might be completely inappropriate for a delicate flower mantis. Understanding these differences helps you make smart choices rather than relying on guesswork.

Getting feeder insects right prevents the majority of nutritional problems you will encounter in carnivorous invertebrate keeping. Animals fed a steady diet of high-quality, properly maintained feeders develop normally, molt successfully, and live out their full lifespans. Those fed neglected, starved, or inappropriate feeders often show stunted growth, failed molts, and shortened lives. The connection between feeder quality and animal health is immediate and observable in ways that become obvious once you know what to look for.

New keepers often ask which single feeder insect is best, hoping for a simple answer that covers all situations. The reality is more nuanced because different invertebrates have different needs, and variety itself provides nutritional benefits. Some keepers also wonder whether wild-caught insects are acceptable or whether only commercially bred feeders are safe. Others want to know whether they need to maintain their own colonies or can rely entirely on purchased feeders. These questions deserve thoughtful answers based on your specific keeping situation and the species in your care.

This article walks you through the common feeder insects available, their nutritional strengths and weaknesses, and how to select appropriate feeders for different invertebrate species. You will learn how to maintain healthy feeder colonies, what gut-loading means and why it matters, and how to avoid the most common mistakes that lead to nutritional deficiencies in captive invertebrates.

Crickets remain the most widely available and commonly used feeder insect in the hobby, and for good reason. They are affordable, come in multiple sizes from pinhead nymphs to large adults, and their movement triggers strong feeding responses in most predatory invertebrates. Nutritionally, crickets offer decent protein levels but have a poor calcium to phosphorus ratio that requires correction through gut-loading or dusting. They also dehydrate quickly and can die off rapidly if not properly maintained with adequate water sources and ventilation.

Dubia roaches have become increasingly popular as a staple feeder because they address many of the problems associated with crickets. They cannot climb smooth surfaces or fly, making them easy to contain. They live much longer than crickets when properly maintained, they do not smell, and they carry less risk of introducing parasites or pathogens. Their softer exoskeleton makes them easier for some invertebrates to consume, and their nutritional profile is generally superior to crickets when gut-loaded properly. Many keepers now consider dubias their primary feeder with crickets as occasional variety.

Mealworms and superworms serve specific roles in invertebrate feeding. Mealworms work well for smaller species and for invertebrates that prefer slower-moving prey. Their hard chitin content is higher than other feeders, which some keepers view as a drawback but which actually provides valuable fiber and structural compounds. Superworms are larger and more active, making them suitable for bigger tarantulas and scorpions, though their strong mandibles mean you should offer them to actively hunting animals rather than vulnerable molting specimens. Both can be stored in refrigeration to slow metabolism and extend usability.

Fruit flies, specifically the flightless varieties, are essential for feeding tiny invertebrate species and young specimens that cannot handle larger prey. Drosophila melanogaster and the larger Drosophila hydei provide different size options for spiderlings, mantis nymphs, and other small predators. Culturing fruit flies requires some initial setup but becomes straightforward once you establish a rotation system with multiple cultures at different stages. Most keepers maintain three to five cultures simultaneously to ensure continuous supply.

Waxworms and butterworms occupy a special category as high-fat treats that should not form dietary staples. These soft, grub-like feeders contain significantly more fat than other options, making them useful for adding weight to thin animals or conditioning females before breeding. However, regular feeding of these fatty options can lead to obesity and associated health problems in species prone to overeating.

Healthy feeder insects display active movement, full bodies without visible shriveling, and normal coloration for their species. Crickets should be jumping readily, roaches should be moving purposefully, and mealworms should be wriggling when disturbed. Feeders that appear lethargic, have dark discoloration, or smell unpleasant should not be offered to your invertebrates because dying or dead feeders transfer their declining nutritional value and potential pathogens to whatever consumes them. Learning to assess feeder health at a glance becomes second nature with experience.

Tarantulas and scorpions accept the widest range of feeder insects due to their size and generalist predatory nature. Adult tarantulas handle everything from roaches and crickets to superworms, while scorpions particularly relish roaches because their movement patterns seem to trigger feeding responses effectively. Younger specimens of both groups need appropriately sized prey, typically starting with fruit flies or pinhead crickets and graduating to larger feeders as they grow. The key with arachnids is matching prey size to predator size so the animal can subdue its meal without risk of injury.

Mantises present more specific requirements because many species are visual hunters that respond primarily to movement. Fruit flies work perfectly for young nymphs, with the transition to house flies, blue bottle flies, and eventually crickets or roaches as the mantis grows. Some mantis species strongly prefer flying prey throughout their lives, while others accept crawling feeders readily. Flower mantises and other delicate species often do better with flying feeders because the presentation matches their natural hunting behavior.

Centipedes are aggressive predators that handle substantial prey items relative to their size. Large centipedes readily take adult crickets, roaches, and even pinky mice, though insect prey provides more appropriate nutrition for regular feeding. Their feeding response is triggered by vibration and movement, so active feeders like crickets often work better than slow-moving mealworms. Always supervise feeding with aggressive centipedes to prevent prey escape into the enclosure where it might disturb the animal.

Assassin bugs, predatory beetles, and other carnivorous insects each have their quirks regarding feeder acceptance. Assassin bugs typically prefer softer-bodied prey like fly larvae or freshly molted crickets. Predatory diving beetles obviously need aquatic prey like mosquito larvae or small aquatic crustaceans. Research your specific species thoroughly because assumptions based on similar-looking animals often lead to feeding failures.

Across all carnivorous invertebrates, the principle of appropriate sizing applies universally. Prey items should generally be no larger than the distance between the predator's eyes for mantises, or roughly the length of the abdomen for tarantulas and scorpions. Offering oversized prey stresses animals and can result in injury or refused meals.

Establishing a reliable feeder supply means deciding between purchasing feeders regularly or maintaining your own colonies. For keepers with just a few animals, buying feeders weekly or biweekly from local pet stores or online suppliers often makes sense. Once your collection grows beyond five or six predatory invertebrates, breeding your own roaches or crickets becomes more economical and ensures you always have feeders on hand without emergency store runs. Dubia roaches make particularly good colony candidates because they breed readily and tolerate beginner mistakes.

Gut-loading transforms basic feeders into nutritional powerhouses by filling their digestive systems with quality foods before offering them to your invertebrates. Twenty-four to forty-eight hours before feeding, provide your feeder insects with fresh vegetables like carrots, squash, and leafy greens along with quality dry foods like fish flakes or commercial gut-load products. Whatever the feeder eats becomes available to whatever eats the feeder, making this step essential for correcting nutritional imbalances inherent in most feeder insects. Think of gut-loading as the difference between offering empty calories and delivering complete nutrition.

Dusting provides another method for supplementing feeder nutrition, particularly adding calcium. Lightly coating feeders with calcium powder immediately before offering them delivers minerals directly to your invertebrate. This technique works especially well for species requiring high calcium intake, though it is less commonly necessary for invertebrates than for reptiles. Some keepers dust occasionally as insurance while relying primarily on gut-loading for their main nutritional supplementation strategy.

Feeding frequency varies tremendously across invertebrate species and life stages. Fast-growing mantis nymphs may eat daily, while adult tarantulas might only need feeding every week or two. Watch your animals rather than following rigid schedules. An invertebrate with a fat, healthy-looking abdomen can go longer between meals than one looking thin. Pre-molt animals often refuse food entirely for weeks, which is normal behavior rather than cause for concern. Learning to read your animals takes time but provides better guidance than any calendar.

Removing uneaten feeders after twenty-four hours prevents them from stressing your invertebrate or, in the case of crickets, actually nibbling on a vulnerable molting animal. Develop a routine of checking enclosures the day after feeding and removing any prey items that were not taken. This habit keeps enclosures cleaner and allows you to track feeding response patterns that help you anticipate molts and other behavioral changes.

Neglecting gut-loading represents perhaps the most widespread nutritional mistake in invertebrate keeping. Feeders purchased from stores have typically been maintained on minimal substrate or cardboard, leaving their digestive tracts empty or filled with nutritionally worthless material. Offering these hollow feeders means your invertebrate receives only the feeder's body tissues without the nutritional boost that gut contents should provide. Taking even a day to feed your feeders quality foods before offering them makes a measurable difference in nutritional delivery. Your animals deserve feeders that actually contain something worth eating.

Relying on a single feeder type creates nutritional gaps even when that feeder is high quality and well gut-loaded. Crickets alone, for example, provide reasonable protein but consistently poor calcium ratios. Mealworms alone offer different limitations. Rotating between two or three feeder types across your feeding schedule provides more complete nutrition than any single option. Think of variety as nutritional insurance against deficiencies you might not even recognize until health problems appear. Even simple rotation between crickets and roaches improves outcomes significantly.

Offering oversized prey creates stress and potential injury for your invertebrates. That giant cricket might seem like an efficient feeding choice, but a tarantula struggling to subdue prey larger than it can comfortably handle experiences stress that affects its overall wellbeing. Worse, oversized crickets left in enclosures can actually attack vulnerable invertebrates, especially those in pre-molt or freshly molted states when their defenses are compromised. Size prey appropriately and err on the smaller side when uncertain. Multiple smaller feeders always works better than one oversized item.

Using wild-caught feeders introduces significant risk despite the appeal of free food. Insects collected outside may carry pesticide residues, parasites, or pathogens that can harm or kill your invertebrates. Even areas you believe are pesticide-free may have received drift from neighboring properties or been treated by previous owners. The small savings from wild-catching rarely justify the risk of losing valuable animals to contamination. Stick with commercially bred feeders unless you have absolute certainty about the safety of your collection area.

Storing feeders improperly leads to mass die-offs and wasted money. Crickets packed too densely suffocate and create ammonia that kills the survivors. Mealworms kept warm pupate into beetles rather than remaining usable feeders. Roaches maintained without adequate moisture stop breeding and eventually die off. Each feeder type has specific storage requirements that, when ignored, result in losing your investment and scrambling for replacement feeders. Learn what each feeder type needs and provide those conditions consistently.

Quality feeder insects are not optional additions to invertebrate care but fundamental requirements for keeping carnivorous species healthy. The feeders you offer are the sole nutritional source for your animals, making every aspect of feeder selection, maintenance, and preparation directly relevant to your invertebrate's health. Investing attention in your feeder supply pays dividends through properly developing, successfully molting, long-lived animals. Cutting corners on feeder quality always shows up eventually in your animals' condition, while consistent quality feeding produces consistently healthy specimens.

Gut-loading and variety work together to provide complete nutrition that no single feeder type can deliver alone. The few minutes required to feed your feeders before offering them to your invertebrates corrects nutritional imbalances that otherwise accumulate over time into visible health problems. Rotating between different feeder types provides additional insurance that nutritional gaps in one feeder get covered by strengths in another. This two-pronged approach of loading and rotating gives your animals the best possible nutritional foundation without requiring complicated supplementation protocols.

Matching feeder size and type to your specific invertebrate species prevents stress and injury while ensuring your animal can actually consume what you offer. A feeder that triggers no feeding response wastes your effort regardless of its nutritional quality, just as one too large creates problems even if eventually subdued. Learning what your particular species prefers takes observation, but that knowledge makes feeding straightforward once established. Pay attention during early feedings and you will quickly understand what works best for each animal in your collection.

Whether you maintain breeding colonies or purchase feeders regularly, consistent supply matters because hungry invertebrates cannot simply wait while you sort out feeder availability. Plan ahead, keep reserves available, and develop backup sources for situations when your primary supply fails. The minor inconvenience of maintaining this supply chain prevents the major problems that result from forced fasting or desperate measures with inappropriate feeders. Your animals depend entirely on you to provide, so build systems that ensure you always can deliver what they need.