Dried Mealworms for Birds: Why They Get Ignored, and How Many Is Too Many

Dried mealworms for birds are cheaper to keep and easier to store, and they are also the version birds most often refuse. That refusal has a known cause and a known fix.

The quantity question matters more than the dried question, though, and it is the one almost nobody asks. Mealworms are calcium depleting, which means the right amount is a real limit rather than a suggestion.

Dried vs live mealworms

The two most-cited bluebird sources take opposite positions, so this is worth laying out rather than resolving quietly.

Project FeederWatch declines to pick: Some people feed live mealworms while others prefer offering dried larvae (both forms are commercially available).

The North American Bluebird Society treats dried as a legitimate option. Its factsheet presents them as the low-maintenance alternative: They are maintenance-free and may last longer so are considered by some to be more cost effective.

Sialis takes the opposite line, in capitals. Its verdict is I do NOT recommend feeding DRIED MEALWORMS.

A note on that second source, because it matters for how much weight to give it. Sialis.org is the work of one person, Bet Zimmerman Smith, rather than an organization. It is among the most detailed and most cited bluebird references in North America, and it is a named individual's judgment rather than an institutional position. NABS is a non-profit organization. We are quoting both because the disagreement is real, and the distinction between them is the reader's to weigh.

Why birds ignore dried mealworms

If your birds are not eating dried mealworms, the reason is movement, and NABS says so directly.

Its factsheet: However, bluebirds may ignore the lifeless mealworms unless other options for food are limited, giving poor weather as the example of when hunger overrides the preference.

Dried mealworms are not rejected because something is wrong with your batch. They are rejected because a dried larva does not look like prey, and an insect-eating bird with alternatives will take the alternatives.

Two consequences follow. In good weather with insects everywhere, dried mealworms may sit untouched for days, which is normal. And in cold or wet spells, the same dish gets cleared, which is when supplementary feeding is doing something useful anyway.

How to rehydrate dried mealworms for birds

Soak them briefly before you put them out. NABS gives the method and hedges it honestly: Rehydrating the worms with a little water or vegetable oil may make them more attractive to birds.

Warm water, ten minutes, drained before serving. The point is to restore some of the plumpness and smell that drying removed. The source says may, which is not a promise that it works, and neither is this.

Two practical limits. Rehydrated mealworms spoil like any wet food, so put out what will be eaten rather than a full dish. And once wet, they lose the storage advantage that made dried worth buying, so rehydrate per serving instead of by the bag.

How many mealworms is too many?

How many mealworms to feed birds is the question the two sources answer very differently, and both answers are published as guidance.

Sialis sets a per-bird ceiling. Its instruction is to limit quantities to no more than 15 mealworms per day, per bird, attributing the figure to a named source: Fawzi Emad recommends offering about 15 mealworms per bluebird per day.

NABS sets a per-household rhythm. Its guidance is to Offer mealworms in limited quantities just once or twice a day unless poor weather conditions dictate more frequent feeding, with a worked figure: A hundred or so worms offered morning and evening would be more than adequate for a pair with a box of nestlings.

These are measured differently, and the gap survives converting them. Sialis counts per bird per day. NABS counts per family per feeding. Two hundred worms a day shared by two adults and a brood of four or five works out at roughly thirty a bird, which is about double the Sialis ceiling. Note also that NABS calls its own figure more than adequate, so it is an upper bound rather than a target.

We are not going to split the difference and invent a third number. What both sources agree on is the shape of the answer: limited quantities, once or twice a day, more only in bad weather. Sialis puts the same point plainly: Offering an unlimited supply of mealworms is probably NOT recommended, as the nestlings need a varied diet.

If you want a rule that satisfies both, feed the smaller number.

The calcium problem

On mealworms, calcium and bluebirds the two sources agree completely, which is what makes this the load-bearing part of the page.

NABS states the constraint and the reason: Because they do not provide complete nutrition, mealworms should be used as a supplemental food only. And the mechanism: They are calcium depleting, which can leave young birds with weak bones or cause egg binding in laying birds.

Sialis describes the same problem with the timing attached: Mealworms are calcium depleting, and birds a week away from fledging need to have strong bones for that first flight/crash landing. It adds a second reason to moderate, which is digestive rather than nutritional: mealworms are low in calcium and have a tough exoskeleton that can be hard for young birds to digest.

This is the same category of harm behind the broader warning about feeding wildlife the wrong things, which the US Fish and Wildlife Service describes as metabolic bone disease in the context of handouts that displace proper nutrition.

If you are feeding a lot, NABS gives a countermeasure: To counter this, put the mealworms in a plastic bag with calcium carbonate or calcium citrate powder, and shake it gently to coat them. Sialis recommends the same technique and is explicit that it is extrapolated from nutritional research on poultry and parrots rather than from songbird trials.

The simpler version of this rule needs no powder at all. Feed the smaller quantity and the deficiency does not arise, because the parents are still bringing in wild insects for the rest of the diet.

Will mealworms bring bluebirds that are not already there?

Probably not, and NABS is unusually blunt about it: If you have never or rarely seen a bluebird in your yard, chances are they will not show up just because you put out mealworms.

This deserves care, because it sits next to a claim we have quoted ourselves: FeederWatch describes mealworms as one of the only foods that reliably attract bluebirds. Both are accurate and they answer different questions. FeederWatch is saying that among foods, rehydrating them is what works on bluebirds. NABS is saying that a food cannot summon a species that is not in your area.

The popular reading, that a tub of mealworms will produce bluebirds in a yard that has never had them, is the one NABS is warning against. What is likelier is that everything else in the yard finds them first.

Sialis adds that even resident birds need teaching: Bluebirds need to learn to come to a feeder.

Where to put mealworms

Not on the ground, and inside something that excludes larger birds.

NABS rules out the simplest option: If you put mealworms on the ground, they will burrow into the dirt, or other birds like robins will probably eat them all.

Its preferred hardware works by geometry: The best type of feeder is a hopper style where the mealworms can be placed inside the feeder, with the bluebirds entering from a hole at either end. The factsheet specifies a hole of 1½ inches or 1 9/16 inches at each end to exclude larger birds, which is the same principle, and nearly the same measurement, that governs what a nest box entrance hole can and cannot exclude.

Containment is the other half. NABS: To prevent mealworm escape from a feeder, put them in a cat food can or a glass or ceramic dish with smooth sides. Smooth sides matter because live larvae climb.

For storage, live worms can be parked: If you are not planning to raise mealworms, they can be kept in a dormant state in the refrigerator, in small containers with tops that allow some air to enter. Dried worms need no such arrangement, which is their entire advantage.

Where the sources disagree

Question	NABS	Sialis
Dried mealworms	A legitimate option, maintenance-free and cheaper per serving	Not recommended
Why they get ignored	Birds may pass on lifeless worms unless other food is scarce	Same, and does not recommend using them
Quantity	Once or twice a day, about 100 morning and evening for a pair with nestlings	No more than 15 per day, per bird
Calcium	Depleting. Coat with calcium carbonate or citrate if feeding a lot	Same, and notes the guidance is extrapolated from poultry and parrot research
Attracting bluebirds	Will not summon birds that are not already around	Resident birds still have to be taught the feeder
What it is	A non-profit organization	One named individual's reference site

Questions people ask

Why are my birds not eating dried mealworms? Because a dried larva does not move or smell like prey. NABS notes that bluebirds may ignore them unless other food is limited, which is why they often get taken in bad weather and ignored in good.

How do you rehydrate dried mealworms for birds? Soak them briefly in a little warm water, or in vegetable oil, before putting them out. NABS says this may make them more attractive, and does not promise it.

How many mealworms should I feed a day? Sialis says no more than 15 per bird per day. NABS says once or twice a day, and calls about 100 morning and evening more than adequate for a pair with a box of nestlings. Feeding the smaller figure satisfies both.

Are mealworms bad for baby birds? In quantity, yes. Both sources describe mealworms as calcium depleting, which NABS links to weak bones in young birds and egg binding in laying females. As a supplement alongside the insects the parents bring in, they are not a problem.

Do I need to add calcium to mealworms? Only if you are feeding a lot of them. The method both sources give is to shake the worms in a bag with calcium carbonate or calcium citrate powder. Feeding less is the alternative.

Will putting out mealworms attract bluebirds? Not if bluebirds are not already in the area, according to NABS. Other birds will find them first.

Can I just scatter mealworms on the ground? No. NABS says they burrow into the dirt or get eaten by robins and other birds. A hopper feeder with small end holes is the recommendation.

Dried mealworms for birds: the short version

Dried mealworms for birds trade acceptance for convenience. They keep without care, and they get refused whenever the birds have live insects available, which in summer is most of the time. A short soak improves the odds and costs nothing to try.

The number matters more than the format. Both bluebird sources call mealworms calcium depleting and both cap the quantity, though at figures that differ by roughly double, and neither treats them as a diet.

So put out a smaller dish than you were planning to, soak the worms for ten minutes first, and see what happens over a cold wet week rather than a warm one. That is the week the answer actually shows up. Dried mealworms for birds are cheap to test and easy to abandon, which is the best thing about them.

This article contains no affiliate links. Quantities and methods cited here come from published guidance and are not our own testing.