Mealworms
Two species of mealworms, the dark mealworm and the
yellow mealworm occur in Michigan. The dark mealworm
occurs throughout the U.S., while the yellow mealworm is
absent from the southern states.
Mealworm adults are robust, slightly flattened, 3/4 -
1" long beetles. The dark mealworm adult is a dull, black
color, while the yellow mealworm adult is a shiny,
polished dark brown or black. Mealworm larvae are shiny,
smooth, hardened "worms." They have three pairs of
segmented thoracic legs, and two short, horn-like
appendages on the tip of the abdomen. Full grown larvae
are 1 - 1 1/4" in length. Dark mealworms are dark brown;
yellow mealworms are honey-yellow in color.
Mealworms overwinter as partially grown larvae. The
overwintered larvae complete their development in the
spring, pupate, and emerge as adults during the summer
(mid July to early August in Michigan). Adults live for 2
to 3 months. After mating the females deposit 275 to 500
eggs, either singly or in small batches. The eggs are
deposited in areas where the larvae will find ample food.
The eggs hatch in about two weeks. The larvae feed and
grow over a period of 6 to 9 months (as long as 20 months
in some cases), molting a total of 14 or 15 times. Mature
larvae are active and wander in search of pupation sites.
Due to this habit they may be found in any area of the
home. The complete life cycle, therefore, requires 6
months to 2 years for completion. One generation per year
is normal.
Mealworms are scavengers and are most commonly found
in damp, spoiled grain and grain products. Adults and
larvae hide in refuse, sacks, bins, grain and similar
undisturbed situations. Adults and larvae are also found
in cereal products, macaroni, meal, bran, meat scraps,
feathers and dead insects.
Mealworms are popular as fish bait and as food for
many types of small pets. They are easy to raise and
there is information available on this subject. Mealworms
also show great potential as a source of protein for
human nutrition.
Mealworms are seldom a serious problem in homes.
Control should begin with a search for spoiled and
infested grain and grain products. Remember to check bulk
storage items (for example, dog food or bird seed). Also,
it is necessary to locate any accumulations of crumbs and
other food material behind appliances and in upholstered
furniture. Keep in mind that both mature larvae and
adults wander and may be found a considerable distance
from the source of the infestation.
Integrated Mealworm Management
Location of the infestation, followed by destruction
of any mealworms found, will generally control an
infestation.
For a complete listing of suggested control options
for all home, yard and garden insect pests contact your
local Extension Service, found under local government in
the phone book.
Read and follow instructions on the pesticide label.
Heed all warnings. Check with your physician if you have
any concerns regarding your personal health risk.