Week 9: Additional and interesting information about darkling beetles

As discussed in previous posts, the meal-worms will grow into darkling beetles. Some of the meal-worms bred in this project had grown into darkling beetles. Below shows the update of the current progress of the meal-worms.

Picture 1

PHYSICAL CHARACTERISTICS

Darkling beetles are approximately 1.5 inches (3.8 cm) in length. They have chewing mouthparts and one pair of antennae. The antennae are often segmented into 11 parts and are thread-like, bead-like or slightly cubed. The darkling beetle does not have any major distinguishing characteristics. There are no bumps or outgrowths, as they are uniformly smooth and black; one end is easy to tell from the other. Wings of the darkling beetle are fused, rendering this beetle flightless. All these characteristics can be seen in Picture 1 above.

HOW DARKLING BEETLES DEFEND THEMSELVES?

Darkling beetles have a very interesting defense mechanism. If they were disturbed, they assume a head down and tail up position, and if handled roughly, they emit a dark-colored, foul-smelling fluid. This behavior is enough to discourage all but the most determined predators. The fluid washes off easily with water in case of contact with your hands. Coyotes, foxes, hawks, snakes, ravens, and crows often eat darkling beetles. The larger species have no other insect predator as adults.

This dark-colored, foul-smelling fluid seems to be a potential subject which can be investigated further to see if there's any area which the defensive mechanism can be applied on or being mimicked. The compositions of the fluid is not known at the moment, but the defense mechanism is surely quite interesting for a small insect like the darkling beetles, which is good enough to fend off most, but not all of its predators.

Sources:

[1] Woodland Park Zoo (2014). Darkling Beetle. Retrieved from

http://www.zoo.org/page.aspx?pid=1915#.U5VvOfmSySo

[2] Pacific Northwest National Laboratory (2014). What About Dakling Beetles? Retrieved from

http://science-ed.pnnl.gov/pals/resource/cards/darklingbeetles.stm