A Little Bit More
Put a click beetle on its back, and you’ll see that the first and second sections of its thorax (middle body part) are loosely hinged. On the underside of the first section there is a spine that is directed backwards and its tip rests just over the edge of a cavity or groove in the second section. When the spine is pressed with considerable force against the edge of the cavity and then suddenly slips into the cavity, it does so with enough force to jar the entire body of the beetle and flip it into the air as much as 20-25 cm (8-10”). If you grasp a click beetle (they’re harmless), it will click repeatedly even if held upright as it repeatedly snaps its body in an effort to escape.
The unusual clicking behavior is unique to the click beetle family. These insects are usually small, short-legged, longish beetles and tend to be a dark brown or black, although some are colorful. Adult beetles feed mainly on flowers or foliage and are most active at night – they remain hidden and inactive during daylight.
Immature click beetles of many species live in the earth or in rotted wood and look a lot like mealworm larvae. Some click beetle larvae, known as wireworms, are serious crop pests and can do considerable crop damage if in high enough concentrations. One million larvae per acre is not uncommon and counts as high as 25,000,000 per acre have been documented. This kind of concentration can completely undermine any agriculture attempts.
Adult click beetle hiding in goldenrod leaves
Activities
Science & Math – Now I Get It
Objectives: Use math to comprehend a large number
Materials: Access to reference material online or in library
Math is an integral part of understanding our world. Scientists all over the world regularly use math to help them better comprehend what they’re studying and/or to convey that information to others. We’ve provided some numbers of click beetle larvae that may be present in a field with an especially high figure of 25,000,000 per acre. A number like this is so large that it’s almost meaningless. So, let’s put this figure into a more “user friendly” setting.
Have your students compute how many square feet there are in a single acre and then determine how many click beetle larvae would be present in each square foot if we know there are 25,000,000 in one acre. This scaled-down figure should help them visualize the concentration of larvae much better by breaking up the field into small square-foot units.
Single acre is 43,560 square feet in area so there are 574 larvae per square foot[i/]
Key Concepts
Behavior and Regulation, Identification, Populations and Ecosystems, Structures and Functions
Questions
Do you have a question for a naturalist? Go ahead and ask!
It's easy -- just fill out this form, submit your question and you'll receive an answer shortly.