Mealworms
are not really worms at all but are the larval form of the
darkling beetle (Tenebrio molitor). They are clean,
easy to raise, do not carry human diseases and most
importantly are a nutritious food supplement readily
accepted by bluebirds.
Mealworms
can be offered to bluebirds to:
-
Entice
them to use a nest box
-
Assist
the incubating female to find food quickly so she does
not have to leave her eggs for long periods of time
-
Act as
supplementary food for nestlings if food becomes scarce
when weather conditions prevent the parents from finding
insects
-
Help
them survive during spells of severe winter weather
Care of Mealworms:
Mealworms
are easy to raise, requiring only a grain source such as
wheat bran, cornmeal, chicken mash or oatmeal. Add a piece
of potato, apple or banana peel on a piece of paper towel or
cardboard about once a week to provide moisture. Avoid
letting the meal itself become too moist. Mealworms can be
kept in a shallow plastic container with a capacity of 2 to
5 gallons, that is covered with a lid that provides good air
circulation (a cover of screen or perforated metal can be
used). Keep the container in the dark, because as the name
darkling beetle implies, they prefer darkness. If you plan
on raising mealworms, a piece of cloth can be placed over a
portion of the grain to provide a surface on which the adult
beetles can lay their eggs. The mealworms will burrow below
the surface of the grain and undergo a series of molts.
Their development is most rapid at the optimum temperature
of 80° F. After the last molt, the larvae come to the
surface and metamorphose into naked white pupae for 6 - 18
days and then into beetles. Adult beetles have wings but
rarely fly. They lay their eggs 9 - 20 days after emergence
and then die. Egg incubation is 4-19 days. Eventually, waste
products or "frass" will build up and a slight odor of
ammonia will be detected. At this time, the grain needs to
be sifted to separate the worms and adult beetles from the
old grain; the container washed and new grain added. Dry cat
food can be added to the grain to enhance the protein value
of the mealworms for the bluebirds. Mealworm metabolism can
be slowed down by keeping them in the refrigerator for a few
weeks, up to several months (remove the vegetable matter
first).
Feeding Mealworms to Bluebirds:
Perhaps the
biggest challenge is to try to attract bluebirds to your
yard with mealworms. If you already have bluebirds and just
want to ensure they stay, mealworms can be an effective
enticement. If you have never or rarely seen a bluebird in
your yard, chances are they will not show up just because
you have put out mealworms. What will happen is that other
birds in your yard will find them and quickly consume the
entire offering. So unless you have bluebirds around, it
could be a costly and unrewarding venture to offer mealworms
in the hopes of attracting them. However, in cold climates,
small over-wintering songbirds like chickadees, nuthatches,
etc. appreciate a small hanging tin cup of mealworms as much
as bird watchers enjoy watching them come.
There are
several types of feeders that can be used, or you can just
scatter mealworms on the ground. The latter method is least
advised as mealworms are attractive to most birds and they
might all be eaten before bluebirds can find them. The best
type of feeder is the hopper style where the mealworms can
be placed inside the feeder with the bluebirds entering from
a hole at either end. Naturally curious, bluebirds will
readily explore this type of feeder and quickly recognize it
as a food source. The 1 ½" hole at each end will effectively
exclude larger birds. Smaller birds will soon catch on, but
an aggressive male bluebird will usually defend "his"
feeder, especially if he and his mate are nesting nearby.
Some find that putting a flat saucer with a few worms in it
on top of the hopper feeder will help draw the bluebird’s
attention to the location of the feeder. Once they become
familiar with the routine, the saucer should be removed and
mealworms placed inside the feeder. The location of the
feeder can also be moved as the birds become familiar with
it, and then moved to a spot where it is easier for you to
watch them feed. One of the highlights of feeding mealworms
to bluebirds is watching the fledged young start coming down
to the feeder, first begging to be fed and eventually
figuring out for themselves how to get the tasty treats on
their own.
Because they
should be used as a supplemental food, mealworms should only
be offered once or twice a day unless poor weather
conditions dictate more frequent feeding. A hundred or so
worms offered morning and evening would be adequate for a
pair with a box of nestlings.
