Mealworm
Contact: Eric Day, Manager, Insect Identification Laboratory
August 1996
Mealworm
Size
1/2 to 5/8 inch (12-15mm)
Color
Yellow or dark depending on type
Description
The yellow mealworm (Tenebrio molitor) and the dark
mealworm (Tenebrio obscurus) are very similar in appearance. The
adults are large beetles, 12-15mm in length. The adult of T. molitor
is dark shiny brown to black; T. obscurus is a dull black. The
larvae resemble wireworms and are familiar to many people as dried
food for aquarium animals.
Habitat
In cabinets and pantries where cereal foods are stored.
Life Cycle
Eggs are laid singly or in clusters during the spring.
Each female lays about 275 eggs which hatch in 4 to 14 days. Larvae
may spend up to two years in this stage depending on the environment.
Most larvae mature by fall and pupate in the spring, with the
pupal stage lasting 7 to 24 days. Individual larvae may wander
far from the food source to pupate, causing homeowners difficulty
in locating the source of infestation.
Type of Damage
Infest cereal foods.
Control
Controlling mealworms requires carefully inspecting
all cereal foods, discarding the heavily infested material, repackaging
material in new containers, and vacuuming kitchen cabinets.
Interesting Facts
Yellow mealworm larvae are known as "golden
grubs" and make excellent fish bait. Although these insects
are world-wide in distribution, they are rarely of major importance.