Diet – What do bluebirds eat
- Diet – What do bluebirds eat?
- What Do Bluebirds Eat?
- Attract Bluebirds With Their Favorite Foods
- Natural Foods for Bluebirds
- Feeding Bluebirds in the Yard
- What Bluebirds Won’t Eat
- Attracting Bluebirds Beyond Foods and Feeding
- How to Attract Bug-Eating Birds
- Bug Eaters
- Eastern Bluebird
- Diet and Foraging
- Welcome to the Birds of North America Online!
- Food Selection and Storage
- Nutrition and Energetics
- Metabolism and Temperature Regulation
- Drinking, Pellet-Casting, and Defecation
- Feeding Bluebirds
Diet – What do bluebirds eat?
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What Do Bluebirds Eat?
Attract Bluebirds With Their Favorite Foods
Bluebirds are some of the most desired backyard birds, but it can be difficult to get these colorful birds to visit feeders without correctly answering the question, what do bluebirds eat? Because bluebirds stay in parts of their range year-round, the answer changes depending on the time of year and how the birds’ nutritional needs vary each season.
Natural Foods for Bluebirds
Bluebirds are thrushes, the same types of birds as American robins, hermit thrushes, solitaires, and fieldfares, and they share the same type of diet. Depending on the season, habitat, activity level, and general food availability, bluebirds eat:
In general, bluebirds are insectivorous, and eat primarily insects throughout the spring, summer, and early fall. As cold temperatures kill insect populations in late fall and winter, the birds will consume more fruits when they can’t find enough insects. Southern populations of birds will eat more insects year-round, but will switch to fruit-based diets during cold periods.
Feeding Bluebirds in the Yard
Bluebirds eat the same types of foods in the yard as they eat in any other habitat, and planting bird-friendly landscaping that includes berry bushes and fruit trees for birds is best to feed bluebirds. At the same time, all insecticide and pesticide use should be minimized or eliminated so bluebirds can find plenty of insects to eat, and cobwebs should be left intact to encourage spider populations. Bluebirds will eat the spiders while other birds use the web material for nesting.
There are a variety of foods that can be added to bird feeders to tempt hungry bluebirds. To supplement bluebirds’ diet at the feeders, consider offering:
These foods should be offered in broad, open feeders that will help these thrushes feel comfortable and secure. Trays and dishes are best, as bluebirds will not typically perch on narrow ledges or short perches, but providing a cover over the feeding area will help keep the food protected from rain or snow. Live mealworms, especially, should be offered in small glass or plastic dishes with smooth sides to prevent the worms from crawling out of the feeder before they are eaten. Winter bluebirds may also visit a bird feeder garland that includes cranberries or other fruits, though they will not be interested in popcorn or cereal strings.
Because many of bluebirds’ favorite foods are very rich, it is best to offer them only in small quantities that the birds can consume in just one or two days. This will prevent bully birds from usurping all the food and chasing bluebirds away, since these colorful thrushes are not usually aggressive at bird feeders and will often yield to larger or more energetic birds.
What Bluebirds Won’t Eat
It is important to note that bluebirds won’t usually eat the most common foods offered to backyard birds, such as whole sunflower seeds, millet, and mixed birdseed. While bluebirds will sample sunflower chips when they are easily available and no other foods are abundant, these birds don’t typically eat seed. They also don’t sip hummingbird nectar, stay away from whole peanuts, and aren’t big fans of cracked corn. Avoiding these less desirable foods at a feeder buffet or separating feeding stations to provide a bluebirds-only section can help attract bluebirds to the feeders.
Attracting Bluebirds Beyond Foods and Feeding
It can be tricky to feed bluebirds, and understanding what bluebirds eat is the first step to successfully attracting these birds to the yard. Along with food, adding a clean bird bath and a suitable bluebird house can entice bluebirds to visit. Heated bird baths are especially critical for winter bluebirds, and roosting boxes are also useful in the colder months. While it is important to be patient while waiting for bluebirds to discover different foods in the yard, adding these extra attractions can make any yard bluebird-friendly.
How to Attract Bug-Eating Birds
As a founding employee of Gardener’s Supply, I wore many different hats over the years. Currently, I have my own company called Johnnie Brook Creative. The gardens around my home in Richmond, VT, include a large vegetable garden, seasonal greenhouse, cutting garden, perennial gardens, rock garden, shade garden, berry plantings, lots of container plants and a meadow garden. There’s no place I’d rather be than in the garden.
There are lots of great reasons to make your yard and garden more welcoming to birds. But here’s one more: pest control.
Most backyard birds eat a combination of seeds, berries and insects. But in late spring and early summer, birds are busy filling the mouths of their hatchlings, and baby birds like nothing better than freshly caught bugs.
That’s good news for gardeners, because garden pests are usually at their peak in late spring and early summer. Our bird friends can save us lots of headaches by combing our gardens for cabbage worms, whiteflies, aphids, earwigs, grasshoppers, cucumber beetles and grubs!
Below is a list of common backyard birds and the pests they eat. But first, a few tips on how to make your yard bird-friendly during the spring and summer months.
When designing a landscape to attract birds, it’s important to provide places where they can hide or take cover from the weather. During the spring and summer, birds also need nesting sites. Twiggy shrubs and small trees offer many appealing nesting options. If your landscape is always tidy and well coiffed, you might consider designating one area that can be allowed to develop more naturally. Remember that more nesting birds means more hungry mouths to feed and more doting parents combing your yard for food.
Birds are attracted to water for drinking and bathing — especially if that water is moving. If you already have a birdbath, consider adding a bubbler to it. If you don’t already have a birdbath, think about an outdoor fountain instead. You’ll provide the attraction of moving water, while adding an appealing sculptural feature to your garden as well. Installing a small pond with a solar-powered fountain or a re-circulating waterfall will draw birds from blocks away.
Most people, who feed birds, put their feeders away once warm weather arrives. But even birds that spend most of their time eating insects enjoy the occasional snack. Keep at least one feeder filled with a quality seed blend that will appeal to chickadees, grosbeaks, cardinals and sparrows. Also consider non-melting suet cakes that will keep titmice and woodpeckers coming to your yard. While they’re in the area, they’ll munch on insect larvae and other delicacies.
Below is a list of common backyard birds and some of the insect pests they eat. Next time you see or hear a bird in your yard, you can breathe a sigh of relief, knowing that they’re on your side, helping you keep your garden healthy and looking good.
Diet and Foraging
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Figure 2. Foraging methods of Eastern Bluebirds in Clemson, SC, 1996.
Samples based on focal individual samples during egg-laying stage of nest cycles throughout breeding season.
Adult female Eastern Bluebird (Sialia sialis) feeding on Winterberry (Ilex sp.) fruits in winter, Ithaca, New York, January.
Fruit is key to the diet of this species in winter., Jan 01, 2000; photographer M. Read
Adult female Eastern Bluebird, feeding young; Ohio, July.
Washington Co. Ohio; plumage of adult is Alternate (worn), that of young is Juvenal., Jul 15, 2004; photographer J. ZICKEFOOSE
Main Foods Taken
Insects, sp > Forbes, S. A. (1903). The food of birds. Bull. Illinois Lab. Nat. Hist. 1:86-162. Close Forbes 1903 , Beal, F. E. L. (1915). Food of the robins and bluebirds of the United States. U.S. Department of Agriculture Bulletin 171. Close Beal 1915b , Pinkowski, B. C. (1977c). Foraging behavior of the eastern bluebird. Wilson Bulletin 89:404-414. Close Pinkowski 1977c ), and the occasional small vertebrate, including salamanders (PAG) and small snakes (Braman and Pogue 2005).
Microhabitat For Foraging
Generally a sit-and-wait predator; individuals use available perches for staging foraging attempts at ground-living arthropods. Staging sites are usually 0.5 – 15 m above bare ground, grassy areas, and in forest areas with sparse understories. When searching for ripe fruit, individuals land on stalks of fruiting bushes or in fruiting clumps in trees (PAG, JHP).
See Habitat, above. Often in open habitats, with little or no overstory and sparse ground cover, such as old fields, pastures, and orchards. During the nonbreeding season, bluebirds forage in forested areas with more or less closed canopy, sparse ground cover, and shrubby edges (PAG, JHP).
Food Capture And Consumption
Hunt for prey from lookouts while perched upright; locate ground arthropods visually, sallying to the ground to capture prey. Indiv > Preston, F. W. and J. McCormick. (1948). The eyesight of the bluebird. Wilson Bulletin 60:120-121. Close Preston and McCormick 1948 ). Drop-foraging constitutes the method of almost 100% of foraging attempts during the early breeding season in Michigan ( Pinkowski, B. C. (1977c). Foraging behavior of the eastern bluebird. Wilson Bulletin 89:404-414. Close Pinkowski 1977c ) and in S. Carolina and Georgia (PAG); fly-catching, gleaning, and hopping increase in frequency during the summer, fall, and winter, although dropping from a perch is the most frequent foraging method in all seasons (Figure 2). During the breeding season, 80% of foraging attempts are perch-to-ground movements. Hovering is uncommon. There are no significant differences between the sexes in foraging mode.
Take ground arthropods in their beaks; often consume prey at the point of capture, though may take large prey items to a perch and bang the prey item against a substrate by moving their heads from side to side, then consuming the prey. Younger fledglings hop along the ground to forage before acquiring adult drop-foraging habits. Foraging during the breeding season peaks in the morning hours in S. Carolina and Georgia, is lowest at midday, and increases toward evening (PAG unpubl. data). No comparable, systematic data exist on winter foraging habits.
Major Food Items
During the breeding season, ground arthropods. In late summer and into winter, add small fleshy fruits to their mostly insect diet.
In Michigan, from samples over an entire year, the major food items of adults included butterfly and moth larvae (Lep >Phoradendron californicum) and sumac (staghorn sumac [ Rhus typhina] berries, as well as those of smooth sumac [ R. glabra]; Pinkowski, B. C. (1977c). Foraging behavior of the eastern bluebird. Wilson Bulletin 89:404-414. Close Pinkowski 1977c ). In Illinois, the stomach contents of 108 indiv > Forbes, S. A. (1903). The food of birds. Bull. Illinois Lab. Nat. Hist. 1:86-162. Close Forbes 1903 ).
Stomach contents of 855 indiv > Beal, F. E. L. (1915). Food of the robins and bluebirds of the United States. U.S. Department of Agriculture Bulletin 171. Close Beal 1915b ). In stomach analyses, insect prey predominated during the breeding season, and wild fruits during the nonbreeding season. Eastern Bluebirds frequently eat crickets and grasshoppers, which were in half the stomachs sampled. Beetles, butterflies, and moths equaled 20% each of the total sample. Fruits of 60 species were in stomachs of indiv >Microsorex sp. or Sorex sp.; Pinkowski, B. C. (1974e). Predation on a shrew by an eastern bluebird. Wilson Bulletin 86:83. Close Pinkowski 1974e ); snakes ( Flanigan, A. B. (1971). Predation on snakes by eastern bluebird and brown thrasher. Wilson Bulletin 83:441. Close Flanigan 1971 ); salamanders (on v > Bent, A. C. (1949). Life histories of North American thrushes, kinglets, and their allies. United States National Museum Bulletin 196. Close Bent 1949 ).
In Ohio, bluebirds took large items more often and small items less often than statistically expected, based on the frequencies of available large and small prey; prey items greater than the length of a bluebird’s bill equaled only 21% of available prey items, but represented 56% of items that bluebirds ate ( Goldman, P. (1975). Hunting behavior of eastern bluebirds. Auk 92:798-801. Close Goldman 1975 ). Detailed studies from most parts of the range of bluebirds are not available. See Breeding: parental care, below, for list of foods fed to nestlings.
Food Selection and Storage
In Athens, GA, experiments (Davison 1962) showed that under conditions controlling for their seasonal availability, bluebirds take a variety of fleshy winter fruits. The fruits bluebirds took included: blackgum ( Nyssa sylvatica), blueberry ( Vaccinium sp.), camphortree ( Cinnamomum camphora), black cherry ( Prunus serotina), dried current ( Ribes sp.), dahoon ( Ilex cassine), flowering dogwood ( Cornus flor >Elaeagnus umbellata), cherry elaeagnus ( E. multiflora), thorny elaeagnus ( E. pungens), sugar hackberry ( Celtis laevigata), American holly ( Ilex opaca), amur honeysuckle ( Lonicera maachi), Japanese honeysuckle ( L. japonica), laurelcherry ( Prunus laurocerasus), redbay persea ( Persea borbonia), common pokeberry, ( Phytolacca mericana), pyracantha ( Pyracantha sp.), nectar raisins ( Vitis sp.), redcedar ( Juniperus virginiana), Carolina snailseed ( Cocculus carolinus), smooth sumac ( Rhus glabra). No observers report bluebirds storing food.
Nutrition and Energetics
Nutritional requirements remain unstudied. Also very few systematic, controlled studies of energetics. Of the 3 bluebird species, Eastern Bluebirds have the highest wing-loading: 0.298 g/cm 2 (Pinkowski Pinkowski, B. C. (1977c). Foraging behavior of the eastern bluebird. Wilson Bulletin 89:404-414. Close Pinkowski 1977c , Pinkowski, B. C. (1978a). Feeding of nestling and fledgling eastern bluebirds. Wilson Bulletin 90:84-98. Close Pinkowski 1978a ), consistent with the fact that individuals use less airborne foraging than Western and Mountain bluebirds do.
From Buser, C. S. (1980). A time and energy budget study of the eastern bluebird ( Sialia sialis) during the breeding season. Master’s Thesis, Rutgers Univ., New Brunswick, NJ. Close Buser 1980 : average energy expenditure, based on time budget estimates during the breeding season, for 6 pairs with 4 nestlings evaluated in each year, was 70 kJ/d for males and 74 kJ/d for females. The overall similarity obscures the differences in distribution of female and male energy expenditures. For aspects of parental care that have to do with direct care of nestlings (excluding nest construction and incubation, which are activities of females alone), females expend more than twice as much energy as males. In New Jersey during the nest-building phase, females expend about 2.61 kJ/h building nests, about 1.38 kJ/h incubating; in the nestling phase, they expend about 0.97 kJ/h brooding nestlings in first week of life and about 0.16 kJ/h brooding in second week. Females spend about 0.58 kJ/h prov > Buser, C. S. (1980). A time and energy budget study of the eastern bluebird ( Sialia sialis) during the breeding season. Master’s Thesis, Rutgers Univ., New Brunswick, NJ. Close Buser 1980 ).
Metabolism and Temperature Regulation
No systematic, controlled studies of general metabolism or of temperature regulation in adults. Nestlings have endogenous thermoregulatory abilities by around 5–7 d of age (see Breeding: young birds, below). Communal roosting during winter in holes in trees and other cavities of 2 to several dozen indiv > Frazier, A. and V. Nolan. (1959). Communal roosting by the eastern bluebird in winter. Bird-Banding 30:219-226. Close Frazier and Nolan 1959 , Pitts, T. D. (1977b). Eastern bluebird mortality at winter roosts in Tennessee. Bird-Banding 49:77-78. Close Pitts 1977b ). During especially cold days, bluebirds retreat to heating sources such as chimney tops of gas-burning stoves ( Parker, R. L. and I. D. Parker. (1950). Note on behavior of birds on a cold winter day. Auk 67:108. Close Parker and Parker 1950 ). Metabolic rates of nestlings aged 12–14 d in the field were measured by the use of the doubly-labeled water technique; indicated no significant differences between males and females in CO2 production ( Droge, D. L., P. A. Gowaty and W. W. Weathers. (1991). Sex-biased provisioning: a test for differences in field metabolic rates of nestling eastern bluebirds. Condor 93:793-798. Close Droge et al. 1991 ).
Drinking, Pellet-Casting, and Defecation
Drink from ponds, streams, and birdbaths. Casual observations indicate that captives seem to prefer running water to standing water. Adults defecate in flight and while perched.
What do Bluebirds eat? Bluebirds eat many insects including crickets and grasshoppers, and insect larvae.They should NOT eat earthworms because they can’t digest them properly. Although they have been known to eat them when insects are in short supply, they can make the birds very sick. They also eat a variety of native berries such as Eastern Red Cedar; Flowering, Pagoda and Kousa Dogwoods; Red Mulberry; and American Holly. They may also learn to eat mealworms and peanut butter suet.
What can I feed them? Bluebirds generally are not attracted to seed feeders. Although they may sometimes be observed at seed feeders, their main diet consists of insects, insect larvae, and berries. Many Bluebird lovers offer their Bluebirds mealworms. Although mealworms are a great supplement, they are NOT a complete diet and most experts recommend offering no more than about 200 a day to a nesting pair. Some truly devoted Bluebird landlords offer as many as 300 a day to a nesting pair and even more if fledglings from the previous nestings are still hanging around. If you are trying mealworms for the first time, you can usually buy them in a small container from a wild bird store such as Wild Birds Unlimited, PetSmart, etc. in a 500 count container at first to see if your Bluebirds will find and eat them. Once your Bluebirds discover the mealworms, you will want to buy in larger quantities, as it is MUCH cheaper to buy them in large quantities than at a local bird supply store. There are several companies that ship on line:
All are similar in price, including shipping. When ordering online be sure to order at least 5 days in advance of when you will need them.
How can I get the Bluebirds to accept mealworms from me?If you put the mealworms where the Bluebirds will see them, they will almost certainly accept them. You can start by putting them in a small shallow dish (with sides to keep the worms from crawling out and preferably clear glass – both for weight and to allow the birds to see the worms) and placing them near the nestbox location, or somewhere close to the perch (a fence or fencepost, perhaps) that you have seen them hunting from. If you are keeping your mealworms in the refrigerator, let them warm up before offering them for the first few times – the worms’ movement will be likely to attract the Bluebirds’ attention. Then you can slowly move the feeding dish a little further away so as not to attract other birds too close to the nestbox. Eventually you will probably want to place the mealworms in a dedicated Bluebird feeder.
The BBF1 Feeder, for sale at TMBStudios.com
What kind of feeder should I use? There are many birds that enjoy eating the mealworms you offer to the Bluebirds, and if you don’t want to go to the expense of feeding them to all the birds in your yard, you will need a feeder that allows the Bluebirds easy access but discourages or prevents larger birds such as starlings and mockingbirds from gaining access. There are several types of feeders, but the idea behind most of them is providing a small opening that the Bluebirds will have no trouble navigating, but that the other birds will find either too small or uninviting. Our sister shopping site, TMB Studios, offers a number of Bluebird feeders. Our favorite is our own design, now made by Erva Tool, the BBF1.
You can also find other styles online, or in your local bird supply store. You can find plans for making your own feeder .
My Bluebirds won’t go into the feeder I bought for them. What is wrong? Sometimes it takes the Bluebirds a little while to understand how to use the feeder. If you’ve been feeding them from a dish, try putting the dish on top of the feeder at first. The birds will recognize the dish, and go to it. If you’re using the type with plexiglass sides, they may try to go in through the clear sides rather than through the holes at the ends. Once inside, they may have some difficulty figuring out how to get back out of the feeder, and try flying back out through the plexiglass. The specially-designed Bluebird Nut Mealworm Feeder depicted above circumvents all these problems, as its open design does not make the Bluebirds feel trapped.
Some people have tried whistling or calling or ringing a bell every time they place mealworms in the feeder, and have been able to train the birds to come to the feeder when they hear that sound. Others discourage this practice, as they feel it may serve as a “dinner bell” for hawks or other predators.
Is there a less expensive way of obtaining mealworms? Yes, you can raise them yourself. The information below was provided by a friend of BluebirdNut:
Mealworms (Tenebrio molitor) are the larval stage of the darkling beetle. Although nowhere as beautiful, if paralleled to a butterfly, the mealworm is the ‘caterpillar’, the pupae is the ‘chrysalis’, and the beetle is the ‘butterfly’. The fourth stage of the darkling beetle (as is a butterfly’s) life is eggs.
Aside from that, they are an easy to raise source of nutritious food for virtually all insect-eating birds and reptiles.
Being completely candid, the advantages of raising mealworms are the cost savings v. buying them and the ease of raising them. Just about anything else is a disadvantage. Raising mealworms is time consuming, dusty, sometimes smelly, and subject to mite and moth infestations. Raising mealworms is never recommended if anyone in the home has any respiratory problems or allergies.
If you are undaunted by that candor, let’s go raise worms!
Plastic bins: just about any large size and kind will do. One that works extremely well are the plastic, 3-drawer carts with castors. Each drawer is approximately 20″ long x 15″ wide x 7″ deep. Even if one isn’t going to launch 3 bins, the other drawers are great for storing other supplies (except the food medium) that are used.
Food medium: almost any grain product will work – chick starter, oatmeal, cornmeal, wheat bran, etc. (Using crushed sugary cereals should be avoided.) These food mediums each have their advantages and disadvantages. Cornmeal is the easiest for sifting to separate worms from the bin. Sifting to separate residual cornmeal from the worms’ digestive by-product (frass – ok, frass is worm poop) is virtually impossible. However, some folks have difficulty getting worms to grow in cornmeal. Wheat bran is extremely inexpensive, the worms’ digestive by-product sifts out easily, but separating the worms from intact bran is a little more difficult than sifting from cornmeal. Chick starter has two (2) concerns about it. Often chick starter has been treated with antibiotics which are helpful to poultry chicks but not advised for mealworms (nor the Bluebirds that will later eat the worms). The other issue with chick starter is that there are a lot of chunks of ingredients in chick starter that the mealworms just won’t eat. That makes sifting worms out of chick starter quite difficult. For starting one (1) bin, approximately five (5) pounds of bran would be needed. (A 50-pound bag of bran is the best value and actually is used up rather quickly if running 3 or more bins. However, a 50-pound bag is large enough to literally fill a typical garbage can. If storage space is an issue, more frequent purchase of smaller quantities of bran may be preferred. Storage in a clean metal garbage can outside the house (e.g. in a garage) is recommended so as to minimize moth infestations. Moth infestations will be discussed below.)
Moisture/ “drink of water”: for example, apple, carrot, lettuce, potato, etc. Pretty much your own experimentation. We’ve had great results with apple, cut in half, cut out the seed area, and place skin-down into the food medium so the cut face of the apple is even with the surface of the bran. The skin keeps the bran from absorbing the moisture from the apple. The mealworms eat these moist items for hydration. Actual water is not necessary for mealworms.
Cover: layer three sheets of brown paper (e.g. a paper grocery bag) cut to size for the bin. The paper enhances the darkness that the worms prefer, it helps insulate the growing worms during drops in the room temperature, and the worms and beetles like to crawl among these layers of paper – sometimes making it easier to find them to pick them out.
Dust Mask: to wear when it becomes time to sift frass out of the bin; the dust mask minimizes inhalation of the frass. Outdoor sifting – in the shade – is best if the weather is warm and dry.
Sifters: Not a baking flour-sifter. As worm growth progresses, two (2) kinds of sifting processes may be needed. 1) Sifting worms out of the bin for putting into the feeder; 2) sifting frass from the bin to allow space for refreshing the food medium. Most folks who raise mealworms have tried a wide variety of sifters/strainers – looking for the right one. Perhaps you will, too. Basically, one that holds 1-2 cups of the bin’s contents at a time, has a handle, and is made of fine mesh will work well for the job of sifting out frass. For separating worms, a medium-mesh nylon net placed in an embroidery hoop has been our best find … so far. This embroidery hoop/mesh set-up allows too-small of worms to fall through back into the bin while briefly holding on to the larger worms to dump into a container. In any event, no sifter will likely be needed for at least the first couple of months.
Starter Supply of Worms: this should be 50-100 worms (or pupae or beetles). If you have beetles they will produce eggs most quickly since the beetles are already the adult breeding form. Starting with worms will require approximately two (2) weeks until they become pupae; pupae require approximately two weeks to become beetles. (Therefore, starting with worms will require approximately a month just for breeding beetles to appear.)
Since Indian meal-moth eggs are found in almost all grain products, it might be helpful to bake the food medium to kill any moth eggs that arrived in the food medium, before putting the food medium into the bin. For purposes of this discussion, we’ll select wheat bran as the food medium. Baking can be done in the regular oven or microwave. If in the microwave, this is not a long process. Generally, 10 cups of bran need microwaved for only about 4 minutes. However, microwave ovens vary in power. So, until you are familiar with how your microwave will work on the bran (or other food medium), watch it constantly. (It is possible to burn or ignite the bran.) Regular oven baking requires however long for the center of the amount of bran being baked to reach 212 Fahrenheit (the “boiling point”). (Note: if there are already moths in the home, they will lay new eggs in the baked bran. The baking will only kill the eggs that were in the new bran.)
Thoroughly cool the bran and then place a 3-4″ deep layer into the bin.
Add the apple (first cutting out the seed area will eliminate seeds later being caught during sifting)
Add your starter supply of worms, pupae, or beetles
Cover with the brown paper
Keep in a warm, dark area (“Warm” is 70 Fahrenheit or warmer. Cooler temps won’t harm the bins but will add months to the time needed for worms to grow.)
If the apple dries out, leave it – beetles often lay their eggs right in the apple. If the apple becomes moldy or rotted and is wetting the bran, discard it and replace with fresh. However, keep in mind, the beetle eggs may have been discarded with that rotted apple.
The white, oval-shaped, darkling beetle eggs are extremely tiny (2 mm long x .09 mm wide). A magnifying glass would be needed to see them. However, finding where they are in the first place could be a challenge in itself. The eventual presence of worms will most likely be detected only when the “hatchling” worms have begun to grow and start shedding their skins. Small piles of tiny shed skins can then be seen on the top of the bran. Generally, this stage will be reached about 4-8 weeks after beetles were first placed/appeared in the bin.
The worms are voracious eaters and will shed their skins 10-20 times before they mature and pupate. Beetles generally continue to breed and lay eggs for about 3 months until they die. Sources vary in the number of eggs a female beetle will lay – ranging from 300-500 per female beetle. (Telling beetle gender is not possible with the naked eye.)
Therefore, when the tiny worms begin to appear in a bin, one might want to consider starting a second bin and moving the beetles from the first bin to the second. At this point, there are likely still thousands of yet-unhatched eggs in the first bin. If the beetles continue to remain in the first bin, the eggs that they will continuously lay will eventually be sifted out with the frass and lost.
As the growing worms eat the apple, replace it with fresh apple. The emptied apple skin may be discarded. Additional bran may also be needed. As space allows, more bran may just be added to the bin. Sometimes, frass may need to be sifted out to create space for added food medium. If there are eggs or tiny worms in the frass, they will pass through the sifter with the frass.
Generally, the time from beetles to feeder-size worms is approximately 3-4 months. A rotation of 3 bins – started 1-2 months apart – usually provides an on-going resource of feeder-size worms. As the first bin is dying down and ready to be replaced, the second bin should have feeder-size worms ready, and the third bin is producing little worms. The first bin is ready for fresh bran and beetles. When the second bin is dying down, the third should start having feeder-size worms, and the first have little worms. And so on.
However, until one learns the process and time involvement, of raising mealworms, one bin might be preferred – to supplement buying worms. While raising mealworms is easy, it really is time consuming in order to truly keep up with the bin rotation described above.
If a bin does become infested with mites, pick out whatever mealworms can be salvaged, and discard (outside of the house) the remaining contents, thoroughly wash and dry the bin, and start new. Do not add the salvaged worms to another bin as they may still have mites. Keep them separate until you offer them to the birds or until you are certain they are clean. If in doubt, just immediately offer them to the birds no matter their size.Controlling mites and moths:
In addition to baking the food medium, “friendly” spiders are excellent guards against moth infestations … except if one is uncomfortable with spiders. Spiders will make quick work of moths and take only a few mealworms themselves. While mites themselves will eventually kill the mealworms, moths spin webs in the bran making it unavailable for the mealworms. Indian meal moths will also fly to other grain products in the home such as cereals, pasta, bread crumbs, etc. These, however, are not clothing moths and do not eat fabric.
All that frass:
Mealworm frass is an exquisite plant fertilizer – indoors and out. We do, however, recommend not having it on the top of the soil for indoor plants as watering it will enhance its odor. Otherwise, we’ve not met any kind of plant – leafing, flowering, or fruiting – that doesn’t love mealworm frass.
Can I feed them anything else?
Do I have to feed the Bluebirds if I put up a nestbox? It is not necessary to feed mealworms to your backyard Bluebirds. Bluebirders with trails would have neither the time nor the resources to feed trail box Bluebirds every day. For the backyard Bluebird landlord, feeding mealworms is a wonderful way to help your blues out, especially in bad weather, or during the winter months. During nesting, it’s also a help to the adults so that they don’t have to venture too far away from the nest (that they need to protect) to look for food. Another great reason to offer them — to bring them in closer for viewing!