Bird Food

Mealworms for Birds

Mealworms are the one feeder food that pulls in birds seed will never reach. They are also the easiest food to over-offer, and the season when that matters most is the one when everybody offers most.

Mealworms are the larvae of the darkling beetle, Tenebrio molitor, sold either live in a tub of bran or dried in a bag. They are the only common feeder food that reliably attracts insect-eating birds, which is to say the birds that walk past your sunflower without a glance: bluebirds, wrens, robins, catbirds, phoebes and, in migration, the occasional warbler.

They are also the food most easily overdone. A dish kept permanently full is an expensive habit for you and a nutritionally lopsided one for a bird feeding nestlings.

This page covers the live-versus-dried decision, how to rehydrate dried worms so birds actually take them, how to serve them without feeding the neighborhood starlings, and what quantity makes sense across the year.

Which birds eat mealworms#

Mealworms sort your yard into two groups fast. The seed birds mostly ignore them, and the insect eaters treat them as the best thing that has happened all week.

Woodpeckers and nuthatches will take the odd worm but are better served by suet. If your goal is bluebirds specifically, the dish is only half the job: the other half is nest boxes and open mown ground, covered in how to attract bluebirds.

Live versus dried#

Live mealworms move, and movement is the trigger. A bluebird scanning from a wire spots a writhing dish from a considerable distance. Dried worms are inert, so birds usually have to be taught they are food, typically by starting with live worms or by mixing the two for a week.

Live worms need looking after. Keep them in a smooth-sided container with an inch or so of wheat bran or rolled oats, add a slice of carrot or potato twice a week for moisture, and pick out anything dark or soft. Refrigeration keeps them dormant. Warm them to room temperature for an hour before serving or they will barely move, which defeats the point.

How to rehydrate dried mealworms#

Cover the worms with warm, not hot, water and leave them 10 to 20 minutes. They will plump up, soften and roughly double in weight. Drain off the excess and serve.

This is worth the trouble for two reasons. Softened worms are much more readily taken, and they carry water rather than pulling it out of the bird. In a hot, dry spell that second point matters, particularly for an adult carrying food to nestlings that cannot drink.

Rehydrate only what you plan to put out that day. Soaked worms left in a dish go slimy and sour within a day in summer heat, and a wet mass in a hot plastic dish is a mold problem waiting to happen.

Serving them without feeding starlings#

An open dish of mealworms is an open invitation to European starlings and house sparrows, both of which can clear it in a couple of minutes. Three things help.

• Use an enclosed feeder with entry holes about 1.5 inches (38 mm) across. Bluebirds, wrens, chickadees and titmice go in; starlings do not fit. The designs are compared in mealworm feeders.
• Use a smooth-sided dish at least 1.5 inches (4 cm) deep so live worms cannot climb out. Glass, glazed ceramic and slick plastic all work; rough wood does not.
• Serve on a schedule and let the dish run empty. A dish that is full for 20 minutes a day is far less useful to a starling than one that is full all day, and the birds you want learn the timing quickly.

Site the dish in the open with a clear view, 5 to 6 feet (1.5 to 1.8 m) up, and within sight of a perch such as a fence line or a wire. Bluebirds want to look at their food before they commit to it.

How many to offer#

The honest answer is fewer than most people put out. Mealworms are a supplement to a diet of wild insects, not a food source in their own right.

• Ordinary conditions: a small handful once or twice a day, adjusted so the dish empties and stays empty for most of the day.
• A bluebird pair you are feeding regularly: the widely repeated figure is about 15 worms per adult bird per day, split into two servings.
• Cold snaps and late-spring freezes: this is when a mealworm dish genuinely helps, because the wild insect supply collapses. Offer more freely for a few days, then return to normal.
• Continuous cold, ice storms, prolonged wet: see feeding birds in extreme cold, where high-fat foods matter more than protein.

Nesting season, in practice#

From roughly April through July, a mealworm dish stops being a novelty and starts being a resource the local pair may plan around. That is the moment to be deliberate.

Keep the twice-daily schedule and the measured amount. Do not switch to an always-full dish because the birds are visiting more often, which is the natural temptation. Watch what the adults do with the worms: if they are carrying every single one straight to a box, cut the serving back and let them go hunting.

Everything else about this stretch of the year, including the foods worth adding and the ones worth pausing, is in feeding during nesting season. If you are hosting a box, nest boxes: sizing and siting matters more to your bluebirds than the dish does.

Storage and hygiene#

Dried mealworms keep for six months or more in a sealed container somewhere cool and dry. They attract pantry moths and mice if left in the bag, so decant them, the same argument made in storing bird seed.

The dish needs washing more often than a seed feeder, because you are serving a moist protein food outdoors in warm weather. Rinse and scrub it daily in summer, and give it the full clean weekly using the method in how to clean a bird feeder. Any residue that has gone dark or smells sour goes in the trash, not back in the dish.

A mealworm routine that works#

• Buy dried unless you are actively trying to recruit a new bluebird pair, in which case start with live.
• Soak the day's worms in warm water for 10 to 20 minutes before serving.
• Serve twice, morning and mid-afternoon, in a measured amount that empties.
• Use an enclosed dish at 1.5 inch (38 mm) entry holes if starlings find you.
• Cap the quantity from April to July, and keep eggshell calcium available nearby.
• Wash the dish daily in summer heat and fully once a week.

Pair the dish with fruit and suet and you have covered nearly every non-seed eater a North American yard is likely to get. Which bird takes what, across every food on the site, is laid out in the bird food chart.