Click beetles, belonging to the family Elateridae, are a diverse group of insects found worldwide. Known for their unique clicking mechanism, these beetles and their larvae, called wireworms, exhibit varied feeding habits. This article delves into the dietary preferences of click beetles and wireworms, exploring their role in the ecosystem and potential implications for agriculture.
Introduction to Click Beetles
Click beetles are easily identifiable by their ability to snap a spine-like structure located on their thorax into a groove beneath the pronotum. This action creates a clicking sound and allows the beetle to flip into the air, a defense mechanism against predators and a way to right themselves when overturned. The name click beetles apply to insects in the family Elateridae. They also have other common names, such as snapping beetles, spring beetles, elaters, and skipjacks. While some other insect families possess similar mechanisms, the Elateridae family is considered the "true click beetles." Examples of false click beetles include members of the family Eucnemidae and Cerophytidae.
This cosmopolitan beetle family boasts up to 9300 known species distributed globally. Close to 1000 of these species are native to North America. The eyed click beetle (Alaus oculatus) is one of the most well-known members of this family. Another popular group is the Pyrophorus (also known as fire beetles).
Physical Characteristics
Snapping beetles exhibit variations in size and appearance. While some species are large and colorful, others are dull-colored and measure less than 2cm (0.78 inches) in length. Most click beetles have an elongated shape with parallel sides and a flattened body. Smaller species typically measure around 0.6cm (1/4 inches) long. However, larger species, such as the Alaus oculatus, can reach lengths of 1 to 1.5 inches (2.5cm to 3.8cm). The adult beetle is long and thin (Arnett, et al 1980). Most species are brown or black, although some exhibit bright colors. The eyed click beetle (Alaus oculatus) is recognized by its prominent oval eye spots on the pronotum. These large white spots are a distinctive coloration pattern that make the beetle appear to have large eyes on its back, affording it a little extra protection from predators who may be startled at the sight of seemingly threatening "eyes" (Woodruff 1999). The beetles are covered in minute scales that function well as protective coloration (Encarta 1999).
Click Beetle Behavior and Habitat
Adult snapping beetles are generally nocturnal. They are mostly outdoor insects living in fields, gardens, and bushes but rarely indoors. They spend most of the day hidden under barks or near plants. However, they become more active at night and are often attracted to light sources. Sometimes, in the mornings, they can be found resting on the sides of buildings near light sources.
Read also: Spider Beetle Identification
Adult Click Beetle Diet
Adult click beetles are primarily herbivorous. They feed on the leaves of various plants and are attracted to sweet liquids like nectar and plant juices. Alaus oculatus diet consists of nectar and plant juice. However, the extent to which adult click beetles feed varies among species. Some species feed very little, and farmers generally do not consider them significant agricultural pests.
Wireworm Diet
The larvae of click beetles are called wireworms. The larva of Alaus oculatus are slender and are up to 2 inches long, hard-shelled, yellowish to dark brown, and jointed (Nielson 1997). The larva have dark heads and appear segmented. They have three pairs of legs. These brownish, hard-bodied worms are cylindrical and often measure between ½ to 2-½ inches (1.2cm to 6.4cm) in length. Wireworms exhibit diverse feeding habits depending on the species.
Decomposers: Most species feed on decaying plant matter in the soil, such as rotting wood. As larvae, some click beetles eat decaying materials and enrich the soil.
Agricultural Pests: Many wireworm species are considered agricultural pests, feeding on plant roots, sprouts, and seeds. Common crops they target include potato, strawberry, corn, and wheat.
Predators: Some wireworm species are insectivorous, preying on other insects and larvae in the soil. Eastern eyed click beetle larvae are known as wireworms and typically live in rotting stumps and logs where they are predators of other insects - especially larvae of longhorned beetles that might also be feeding in the dead and decaying wood.
Read also: The Goldenrod Soldier Beetle
Click Beetle Diet and the Ecosystem
Click beetles and wireworms play various roles in the ecosystem. Some larvae eat decaying materials and enrich the soil. Others help control other insects by preying on their larvae. Others help limit plant growth by grazing on seeds or roots. The larvae must grow, however, and they eat different foods depending on species. Some eat decaying materials in rotting logs or in soil. Some, living in soil, eat seeds, sprouts, and roots of plants.
Click Beetles as Pests
While adult click beetles cause only minor crop damage, wireworms can be serious agricultural pests. They attack various crops and tend to be resistant to insecticides. Adult snapping beetles hardly eat at all. Species that feed only eat very little, so farmers do not consider them serious agricultural pests. Unfortunately, we cannot say the same for their larvae. They attack various crops and tend to be very resistant to insecticides.
Control Methods
Methods of controlling wireworm infestations include:
- Clean cultivation: Removing plant debris and weeds that can serve as food sources for wireworms.
- Clean fallowing: Leaving fields unplanted for a period to disrupt the wireworm life cycle.
- Planting seed shallow and under warm conditions: This allows the seeds to germinate faster than the wireworm can damage it.
Click Beetles and Axolotls
Some individuals have considered raising click beetle larvae (wireworms) as a food source for axolotls. However, there are factors to consider:
- Hard Shell: Some fire salamanders don't like to eat wire worms, because those larvae seem to have a rather hard shell. Wireworms have a hard shell, which may make them difficult for axolotls to digest.
- Shedding: It may be best to feed wireworms to axolotls only after they have shed, similar to mealworms.
- Escape Artists: Click beetles are notorious escape artists, capable of flying and jumping. This makes containing them in a colony challenging.
Click Beetle Diet: Raising a Colony
If you're interested in raising a click beetle colony, here are some considerations:
Read also: The Diets of Beetles
- Species Identification: Identify your local click beetle species to understand their specific dietary needs. There are so many species of click beetles and wire worms that you're going to have to identify your local species and look up your diet.
- Larval Diet: Wireworms primarily feed on root vegetables and decaying veggies. Potatoes may be a suitable food source.
- Adult Diet: Adults eat pollen and nectar.
- Enclosure: A shoebox with soil may be a suitable enclosure.
- Alternative: Consider starting with a mealworm colony and allowing some to pupate and morph into beetles, as this may be easier than collecting wild click beetles.
Are Click Beetles Dangerous?
No. Click beetles are not dangerous to people. Adults can cause minor crop damage, but they’re not considered serious agricultural pests. Click beetles rarely invade homes. However, if you find one in your home, they probably entered by accident or to escape from cold weather. You can pick the insect up by hand or use a vacuum to remove it. Click beetles often jump as a defensive response. Their acrobatic jump and the clicking sound startle predators and allow them to escape.