Tarantula (Mexican Red Knee) — Food & Nutrition Products

Mexican Red Knee Tarantulas are obligate carnivores that rely entirely on live or pre-killed prey for their nutritional intake. In the wild, they ambush insects, small invertebrates, and occasionally tiny vertebrates along the forest floor of semi-arid Mexican scrublands. Their metabolism is slow compared to many other pets, and they can go weeks or even months without eating, particularly during pre-molt periods. Understanding this natural feeding rhythm is essential to selecting the right products and avoiding overfeeding.

The bulk of their diet should consist of appropriately sized feeder insects. Crickets, dubia roaches, and mealworms form the staple prey items for most captive Mexican Red Knees. The key nutritional considerations are protein content, fat balance, and calcium-to-phosphorus ratio of the feeder insects themselves. Gut-loading feeders with quality vegetables and grains before offering them to your tarantula dramatically improves the nutritional value of each meal.

Because tarantulas digest their prey externally — injecting digestive enzymes and consuming the liquefied contents — the internal nutritional quality of the feeder insect matters far more than its outer shell. Feeder insects raised on nutrient-poor substrates provide correspondingly poor nutrition. Investing in high-quality feeder sources or raising your own colony with proper gut-loading diets is one of the most impactful choices you can make for long-term tarantula health.

Juvenile Mexican Red Knees have faster metabolisms and should be fed more frequently than adults, typically two to three times per week. Adults in good condition may only need a meal every one to two weeks. During the weeks leading up to a molt, most tarantulas will refuse food entirely, and this is completely normal. Attempting to force-feed or leaving live prey in the enclosure during this vulnerable time can actually injure your spider.

The single most important factor when selecting feeder insects is size. The prey item should be no larger than the tarantula's opisthosoma (abdomen) and ideally somewhat smaller. Offering oversized prey can stress the spider and, in rare cases, lead to injury. For slings and juveniles, flightless fruit flies, pinhead crickets, and micro mealworms are appropriate. Adults can handle full-size crickets, adult dubia roaches, and superworms.

Freshness and vitality of feeder insects are significant quality markers. Lethargic, dehydrated, or dying feeders are nutritionally depleted and may introduce bacteria or parasites into the enclosure. When purchasing feeders from a retailer, look for active, well-hydrated insects housed in clean containers with access to food and moisture. If ordering online, choose suppliers that ship with cold or heat packs seasonally and guarantee live arrival.

Variety in feeder selection helps round out the nutritional profile over time. While crickets are the most commonly available and affordable option, rotating between crickets, dubia roaches, superworms, and occasional hornworms or waxworms provides a broader spectrum of amino acids, fats, and micronutrients. Waxworms and butterworms are high in fat and should be offered sparingly, functioning more as occasional treats than dietary staples.

Avoid feeder insects that have been exposed to pesticides, chemical substrates, or unidentified food sources. Wild-caught insects carry parasites and toxin risks and should never be used. Commercially bred feeders from reputable suppliers raised on controlled diets are the safest option. If you maintain your own feeder colony, keep it in a separate area from your tarantula enclosures to minimize cross-contamination.

Crickets remain the most widely available and versatile feeder insect for Mexican Red Knee Tarantulas. They are inexpensive, come in a range of sizes suitable for all life stages, and are readily accepted by most tarantulas. The main drawback is their relatively short shelf life and the noise adult crickets produce. Keeping a dedicated cricket habitat with egg crate hides, a dry grain-based food, and a gel-based water source will extend their usability and improve gut-load quality.

Dubia roaches are increasingly favored by tarantula keepers for several practical reasons. They are quiet, do not climb smooth surfaces, have a longer lifespan than crickets, and carry a superior protein-to-fat ratio. Dubias are also easier to maintain in a home colony, reproducing steadily in warm, dark conditions with minimal odor. Their softer exoskeleton compared to some other roach species makes them particularly suitable for tarantulas, which must externally digest their prey.

Mealworms and superworms offer convenience and long shelf life. They can be kept in a container of bran in a cool area for weeks. However, their chitinous exoskeleton is harder than most other feeders, and their tendency to burrow into substrate means they may not always be accessible to the tarantula. Offering them in a shallow dish or using tongs to present them directly helps ensure the spider locates and captures the prey.

Hornworms serve as an excellent hydration-boosting feeder due to their high moisture content. They grow rapidly, so purchasing them small and using them promptly is important. Waxworms and butterworms are fatty and soft-bodied, making them useful for underweight or post-molt tarantulas that need an energy-dense meal. Neither should be offered routinely, as their high fat content can lead to an unhealthy abdomen-to-body ratio over time.

Gut-loading is the practice of feeding nutrient-rich food to feeder insects 24 to 48 hours before offering them to your tarantula. This transforms the feeder from a simple protein source into a more complete nutritional package. Common gut-load ingredients include dark leafy greens like collard greens and dandelion leaves, shredded carrots, sweet potato, and high-quality dry grain mixes formulated for feeder insects.

Commercial gut-load products are available as dry blends or gel-based formulas that combine hydration with nutrition. These products simplify the process and often include calcium, vitamins, and trace minerals that would be difficult to replicate with kitchen scraps alone. Look for gut-load formulas that list whole food ingredients and avoid those heavy in fillers, soy, or artificial preservatives.

Calcium and vitamin supplementation is less straightforward with tarantulas than with reptiles or amphibians, since you cannot dust a prey item the same way you would for a lizard. The most effective supplementation strategy is indirect: ensure the feeder insects themselves have access to calcium-rich foods and supplements before being offered. Some keepers lightly dust feeders with a calcium powder, though the effectiveness of this method for arachnids is debated and data is limited.

Hydration is a critical but often overlooked aspect of tarantula nutrition. While Mexican Red Knees obtain much of their moisture from prey, a shallow water dish should always be available in the enclosure. Gel-based water crystals marketed for feeder insect hydration can also be placed in the enclosure as a supplemental moisture source, though they should not replace a clean water dish. Dehydration is a more common health issue in captive tarantulas than nutritional deficiency.

Wild-caught insects are the most significant feeding risk for captive tarantulas. Insects collected from gardens, fields, or wooded areas may carry internal parasites, pesticide residues, or environmental toxins that can sicken or kill a tarantula. Even in areas where pesticide use is minimal, wild insects can harbor nematodes and other parasites that thrive in the warm, humid environment of a tarantula enclosure. Always use commercially bred feeder insects from known sources.

Certain feeder insects pose mechanical risks. Lightning bugs and fireflies contain lucibufagins, which are toxic to many predators including arachnids, and should never be offered under any circumstances. Ants, wasps, and bees can sting or bite the tarantula during a feeding attempt, potentially causing serious injury. Beetles with hard, thick exoskeletons can be difficult for the spider to process and may damage its chelicerae.

Pinky mice and other vertebrate prey items are sometimes offered to large tarantulas, but this practice is generally discouraged for Mexican Red Knees. Their jaws and digestive systems are optimized for invertebrate prey, and vertebrate items carry a higher risk of bacterial contamination, particularly if not fully consumed. The ethical considerations of feeding live vertebrates when invertebrate prey is nutritionally sufficient also weigh against the practice.

Never leave uneaten live prey in the enclosure for extended periods. A cricket or roach left overnight with a tarantula that is not interested in feeding — particularly during a pre-molt period — can chew on the spider and cause wounds. If the tarantula does not strike within a few hours, remove the feeder insect and try again in a few days. This is especially critical for slings and freshly molted individuals whose new exoskeletons are soft and vulnerable.

Long feeding tongs are arguably the most essential feeding accessory for tarantula keepers. Stainless steel or rubberized-tip tongs in the six to ten inch range allow you to present prey directly to the spider without putting your fingers near the enclosure opening. Rubber-tipped tongs are preferable because they grip the feeder securely without crushing it and reduce the risk of injuring the tarantula if accidental contact occurs. Avoid sharp-edged metal forceps, which can harm both the prey and the spider.

Small feeding dishes or escape-proof bowls are useful for containing mealworms and superworms, which tend to burrow into substrate before the tarantula can locate them. A smooth-sided ceramic or glass dish set flush with the substrate surface keeps burrowing prey visible and accessible. Some keepers use bottle caps or shallow jar lids, which work well for slings and juveniles in smaller enclosures.

Prey containment and transport tools matter more than many beginners realize. Clear plastic catch cups with ventilated lids make it easy to transfer individual feeder insects from a colony or retail container to the enclosure without escapees. Fluon-coated containers prevent climbing roaches and crickets from escaping during storage. Having a designated set of feeding tools that are cleaned regularly helps maintain hygiene and reduces the chance of transferring mites, bacteria, or substrate contaminants between enclosures.

For keepers maintaining feeder colonies, investing in quality colony housing and gut-loading infrastructure pays dividends over time. Stackable plastic bins with screened ventilation panels, heat mats with thermostats for dubia roach colonies, and dry grain dispensers keep feeder populations healthy and productive. The initial setup cost for a dubia roach colony, for example, is recovered within a few months compared to purchasing feeders individually from a pet retailer.

Mexican Red Knee Tarantulas do not require daily or even every-other-day feedings. Adults in good body condition typically thrive on one appropriately sized meal every seven to fourteen days. Overfeeding leads to an excessively distended abdomen, which increases the risk of rupture from a fall and can contribute to lethargy. A well-fed adult will have a plump, rounded abdomen without appearing stretched or taut.

Juvenile and sub-adult Mexican Red Knees grow slowly but benefit from more frequent feedings, usually two to three prey items per week. Slings may be offered tiny prey every three to five days. Growth rate in this species is notably slow compared to many other tarantula species, and female Mexican Red Knees can take seven to ten years to reach full maturity. Consistent, moderate feeding supports steady growth without the health risks associated with power-feeding practices.

Seasonal appetite fluctuations are common and normal. Many captive tarantulas eat less during winter months even when kept at stable temperatures, likely reflecting deep circadian and seasonal rhythms. Pre-molt fasting can last anywhere from two weeks to several months in adult Mexican Red Knees. The spider's abdomen will often darken noticeably as the new exoskeleton forms beneath the old one, which is a reliable visual indicator that a molt is approaching and feeding should be suspended.

Keeping a simple feeding log helps track patterns over time. Recording the date, prey type, prey size, and whether the tarantula accepted or refused the meal makes it much easier to identify pre-molt fasting, seasonal rhythms, and any changes in appetite that might signal a health issue. A basic spreadsheet or notebook entry after each feeding attempt is sufficient and becomes an invaluable reference over the lifespan of a spider that can live two to three decades.