Most backyard lizards eat insects and other small arthropods. The typical species you see darting across a patio or fence post, whether it is a green anole, a fence lizard, or a small skink, gets the bulk of its calories from ants, beetles, crickets, spiders, caterpillars, and flies. Some larger or more omnivorous species also eat plant material, fruit, or flower nectar, but insect-hunting is the default. What you should not feed them is a shorter but more urgent list, because a few common backyard creatures, especially fireflies, are genuinely lethal.
How Backyard Lizards Hunt
Lizards use two broad hunting strategies, and the one your backyard lizard favors determines what ends up in its stomach. Some species are “sit-and-wait” predators: they park themselves on a rock, fence, or tree trunk and grab whatever walks or flies within striking distance. Others are active foragers that spend most of their waking hours on the move, covering ground to flush out prey hiding under leaves or debris.
Research on two closely related desert lizard species illustrates how extreme this split can be. The whiptail Cnemidophorus tigris spent about 91% of its five-hour daily activity window moving, while the zebra-tailed lizard Callisaena draconoides moved less than 2% of its ten-hour window.1PubMed. Contrasts in energy intake and expenditure in sit-and-wait and widely foraging lizards The sit-and-wait species ate fewer, larger prey items; the active forager ate more numerous, often smaller ones. A study on Aegean wall lizards found that populations living on human-built stone walls became significantly more sedentary than populations in natural habitats, and their diets shifted accordingly: wall-dwelling lizards ate more mobile prey that came to them, while lizards in wilder settings consumed a higher proportion of sedentary prey they had to go find.2PubMed Central. Aegean wall lizards switch foraging modes, diet, and morphology in a human-built environment
Your backyard is essentially a human-built environment, so the lizards living there are often leaning toward the sit-and-wait end of the spectrum. They pick a sunny perch, wait for an ant column or a passing moth, and strike. That is why you tend to see them sitting still rather than running around.
Common Prey Items and Seasonal Shifts
If you could inventory a backyard lizard’s stomach over the course of a year, you would find a rotating cast of small invertebrates. Ants and beetles show up consistently across seasons and species. Spiders, caterpillars, grasshoppers, moths, flies, and small wasps round out the list. The exact mix depends heavily on what is available, and that changes with the calendar.
A DNA-based diet study of four species of spiny lizards in Mexico found that the variety and evolutionary range of prey items was actually higher during the dry season than the rainy season. When fewer insects are around, lizards diversify and eat whatever they can find rather than specializing. The shift was especially pronounced in species living at higher elevations, where seasonal swings in prey abundance are more extreme.3PubMed. DNA metabarcoding reveals seasonal changes in diet composition across four arthropod-eating lizard species (Phrynosomatidae: Sceloporus) In practical terms, the lizards in your yard eat more diverse prey in winter and early spring, and may focus on a few abundant insect types during summer.
Size matters too. A very small lizard, like a juvenile anole, targets tiny prey: aphids, gnats, springtails, and fruit flies. A larger adult fence lizard takes on bigger game like grasshoppers, beetles, and even small snails. The prey has to fit in the lizard’s mouth, so body size is a hard limit on what is edible.
When Lizards Eat Plants
Not every backyard lizard is a strict insectivore. Some of the larger species you might encounter, particularly iguanas, chuckwallas, and certain skinks, eat substantial amounts of plant material as adults. What is interesting is that even within these species, the youngest individuals are often dedicated insect-eaters. The diet shift happens as they grow.
In the Mexican spiny-tailed iguana, for example, insects made up about 87% of food volume in the smallest juveniles but were nearly absent from adult diets.4PubMed. Ontogenetic plasticity of food habits in the Mexican spiny-tailed iguana, Ctenosaura pectinata A similar pattern shows up in the Peruvian lizard Microlophus thoracicus, where juveniles were mainly insectivorous and adults mainly herbivorous. The adults even developed proportionally wider and taller heads, which may help them process tougher plant material.5PubMed. Ontogenetic Changes in the Diet and Head Morphology of an Omnivorous Tropidurid Lizard (Microlophus thoracicus)
If the lizards in your yard are small anoles or fence lizards, they are eating almost exclusively insects and spiders. If you have larger species visiting, like blue-tongued skinks in Australia or green iguanas in subtropical areas, those adults are also munching on flowers, leaves, berries, and fallen fruit. Some lizards are even documented visiting flowers for nectar, though confirmed pollination by lizards is uncommon on mainlands. A global review found that lizard-flower interactions were recorded on islands about 79% of the time, and only about a fifth of all documented interactions confirmed effective pollination.6Ecography. Environmental and morphological drivers of mutualistic plant–lizard interactions: a global review
Fireflies and Other Toxic Prey
This is the most important section if you keep pet lizards outdoors or if you are thinking about catching bugs to feed a backyard lizard. Fireflies (lightning bugs) are genuinely deadly to many lizard species. They contain chemicals called lucibufagins, which are potent cardiotoxins. Bearded dragons are especially vulnerable, and a single firefly can be a lethal dose.7Veterinary Clinics: Exotic Animal Practice. Dietary intoxications of zoo, exotic, and wildlife species The toxin disrupts heart function, and by the time symptoms are visible, it is often too late. This applies to captive lizards kept in outdoor enclosures during summer evenings when fireflies are active, and it applies if you catch insects from your yard to feed a pet lizard without sorting out the fireflies.
Fireflies are not the only risky prey. Some grasshoppers and caterpillars acquire toxicity from the plants they eat, effectively turning into poison packages. A study using green anoles as predators showed that grasshoppers fed on a particular plant (hop tree, Ptelea trifoliata) became distasteful and toxic to the lizards. When the grasshopper regurgitated during the attack, the plant-derived chemicals in its gut deterred the lizard, sometimes causing the lizard to reject the prey entirely.8PubMed. Tasty on the outside, but toxic in the middle: grasshopper regurgitation and host plant-mediated toxicity to a vertebrate predator Wild lizards generally learn to avoid brightly colored or foul-tasting insects after one bad experience, but captive lizards presented with unfamiliar wild-caught prey do not always get that chance.
The practical takeaway: if you are supplementing a pet lizard’s diet with wild-caught insects, stick to known-safe species like crickets and mealworms from a pet store. Never feed fireflies, brightly colored beetles, or caterpillars you cannot identify. Wild backyard lizards handle this on their own through trial and avoidance learning, but the consequences of a mistake with fireflies are severe.
How Lizards Handle Venomous Prey
Backyard lizards routinely eat spiders, including venomous ones. You might wonder how a small fence lizard survives eating a black widow. The answer is that many lizard species have evolved meaningful resistance to spider venom, though the degree varies.
A study tested three lizard species that overlap geographically with black widow spiders. Southern alligator lizards showed minimal tissue damage and almost no loss of sprint speed after exposure to black widow venom. Western fence lizards showed more muscle damage and immune response but still maintained their sprint performance. Side-blotched lizards fared worst: those receiving the venom ran roughly 25% slower than their baseline, and at higher doses, about 42% slower.9Royal Society Open Science. Preying dangerously: black widow spider venom resistance in sympatric lizards The researchers found that the alligator lizard, which is a dedicated arthropod predator with a strong bite, had significantly lower tissue damage compared to the other species.
For backyard lizards in North America, black widows and other venomous spiders are a normal part of the diet. The lizards that regularly eat them have evolved enough tolerance that the venom is not a serious threat. Smaller lizard species may be more vulnerable, but they also tend to go after smaller spiders. You do not need to worry about your resident fence lizards getting hurt by the spiders in your garden; the lizards are doing you a favor by eating them.
Why You Should Not Hand-Feed Backyard Lizards
It is tempting to leave out mealworms or fruit to attract lizards, but supplemental feeding creates problems. Wild lizards that get easy food tend to change their behavior in ways that leave them worse off overall. Research on fence lizards showed that individuals facing predation pressure traded foraging time for safety: they moved less, became active later in the day, and chose safer but less productive hiding spots. Over time, these lizards grew smaller and produced lighter clutch masses and smaller offspring. The long-term fitness cost was real and lasting, even after the threat was removed.10Wiley Online Library (Ecology). Trading heat and food for safety: costs of predator avoidance in a lizard
That study focused on predation risk rather than supplemental feeding directly, but it illustrates a broader point: wild lizards calibrate their behavior based on environmental signals, and artificial changes to those signals have cascading effects. A feeding station can concentrate lizards in one spot, attracting cats and birds of prey. It can reduce natural foraging behavior, which in turn reduces the pest control that makes lizards valuable in your yard. It can also spread parasites, since lizards from different territories are now sharing a resource in close quarters.
If you want more lizards in your yard, the better approach is habitat improvement: rock piles, leaf litter, native plants that attract insects, and a shallow water dish refreshed daily. Let them forage naturally.
Vitamin D and the Sunlight Connection
Diet is only half the nutritional picture for lizards. Sunlight, specifically the ultraviolet-B component, plays a critical role in their vitamin D metabolism, and this relationship is more important than most people realize.
A study on juvenile bearded dragons found that animals exposed to UVB light for two hours a day had plasma vitamin D metabolite levels about 18 times higher than animals given oral vitamin D supplements instead. The supplement simply could not replicate what UVB exposure did for the lizard’s internal chemistry.11PubMed. Effects of vitamin D3 supplementation and UVb exposure on the growth and plasma concentration of vitamin D3 metabolites in juvenile bearded dragons (Pogona vitticeps) Panther chameleons took this a step further: when researchers gave some chameleons low-vitamin-D diets and others high-vitamin-D diets, the low-D chameleons voluntarily increased their UV exposure by basking more in natural sunlight. They were essentially self-medicating through sun exposure.12PubMed. Panther chameleons, Furcifer pardalis, behaviorally regulate optimal exposure to UV depending on dietary vitamin D3 status
Different species have different adaptations depending on their lifestyle. Sun-loving anoles obtain more dietary vitamin D than shade-dwelling species, but the shade-dwellers compensate with skin that is more sensitive to whatever UV-B they do receive.13PubMed. Ultraviolet exposure and vitamin D synthesis in a sun-dwelling and a shade-dwelling species of Anolis: are there adaptations for lower ultraviolet B and dietary vitamin D3 availability in the shade? For backyard lizards, this means their basking behavior is not just about warming up. When you see a lizard flattened out on a sunny rock, it is simultaneously thermoregulating and manufacturing vitamin D. Disrupting basking spots, whether by removing flat rocks or adding too much shade with landscaping, can affect lizard health as much as removing their food supply.
Lizards as Garden Pest Control
One of the strongest practical reasons to encourage lizards in your yard is their appetite for agricultural and garden pests. Research has documented this effect across multiple crop systems. In both Mexican and Puerto Rican coffee farms, anole lizards significantly reduced infestation rates of the coffee berry borer, a major agricultural pest, in controlled experiments.14PubMed Central. Anolis lizards as biocontrol agents in mainland and island agroecosystems The lizards consumed the borers in high numbers and were effective enough for researchers to describe them as genuine biocontrol agents.
Aegean wall lizards in Mediterranean agricultural settings showed a similar pattern. When lizards were present in experimental plots, the abundance of ground-dwelling arthropods in the 2-to-5 millimeter size range dropped significantly over time. The lizards were especially effective later in the growing season, when other food resources became scarce and the lizards consumed prey in large quantities relative to their body size.15Deep Blue / University of Michigan. Efficacy of the Aegean Wall Lizard (Podarcis Erhardii) as a Potential Biological Control Agent in Mediterranean Agroecosystems A diet study of wall lizards in Portuguese vineyards confirmed that the lizards ate a wide range of arthropod groups, though specific vineyard pests appeared at relatively low frequencies in their stomachs.16Agriculture, Ecosystems & Environment. Trophic ecology of lizards in vineyards: Diet composition and implications for pest control The takeaway is that lizards are not targeted pest-control specialists. They are generalist predators that eat whatever small arthropods are most abundant, and that broad appetite is exactly what makes them useful.
For your garden, this means a healthy lizard population helps keep aphids, ants, slugs, beetles, and caterpillars in check without any chemicals. The lizards are self-sustaining, free, and they work every day the weather allows.
How Artificial Light Affects What Lizards Eat
If you have bright outdoor lights, you may have noticed lizards hunting around them at night. Porch lights and security lamps attract moths and other nocturnal insects, creating an artificial buffet. Research on green anoles exposed to artificial light at night found that the lizards were more likely to stay awake after dark, using the light to explore, forage, and even display to other lizards. But there was a cost: during the daytime, those same lizards were less active, slower to move, and females displayed less often. The light-exposed lizards also accumulated heavier fat pads, suggesting they were eating more overall but expending less energy during the day.17PubMed Central. Artificial light at night alters diurnal and nocturnal behavior and physiology in green anole lizards
This is a mixed bag for backyard lizard health. On one hand, night-active lizards near lights probably eat more insects overall. On the other hand, altered sleep-wake cycles can affect reproduction and stress physiology. If you are trying to support a healthy lizard population, consider using motion-activated outdoor lights or amber-toned bulbs instead of bright white LEDs that stay on all night. The lizards will still find plenty to eat during the day.
How Lizards Get Water
Diet questions inevitably lead to hydration. Most backyard lizards drink from droplets: dew on leaves, rain pooling on surfaces, or water left on plants after you run a sprinkler. They do not typically drink from standing water bowls the way a dog or cat would, though some larger species will use a shallow dish. Misting plants in the morning can make a meaningful difference in arid climates.
Some lizard species have evolved remarkable water-harvesting adaptations. The thorny devil of Australia, for instance, has a capillary network across its entire skin that wicks water from rain, puddles, or even moist sand toward its mouth, where it drinks the collected water one tiny jaw movement at a time. Researchers found the volume needed to fill the capillary system was only about 3% of the lizard’s body weight, and the most ecologically reliable sources were rain and moist sand shoveled onto the lizard’s back by its own digging behavior.18Journal of Experimental Biology. Cutaneous water collection by a moisture-harvesting lizard, the thorny devil (Moloch horridus) Your backyard lizards are not thorny devils, but the principle holds: lizards in dry environments are resourceful about finding water, and providing morning moisture through garden irrigation helps them enormously.
A dripping hose, a birdbath with a rough surface they can climb, or a daily misting routine gives lizards reliable access to the water they need without attracting mosquitoes the way a stagnant dish might. If you already water your garden regularly, the lizards are probably getting what they need from leaf surfaces and damp soil.