Saturday, June 20, 2015

Beetle Pollinators

Long-horned Locust Borer Beetle (a yellowjacket mimic) on Goldenrod

     To continue with National Pollinator Week, let's look at one of the least known, but vital, pollinators: beetles. Due to their sheer numbers (there are more beetle species than any other group of animals studied, making up 40% of known insects), they are responsible for a considerable amount of plant pollination. They are also one of the most primitive pollinators, among the first group of animals to start visiting flowers. Beetles are still the primary movers of pollen for numerous plant families, especially primitive ones like magnolias. As some claim that 88% of flowering plants have been found to be visited by beetles, they may be minor pollinators of numerous other plant species as well.

Chafer Beetles on Maple-leaf Viburnum

     Although many beetles can see color, they often depend on detecting the aromas of the blooms instead. These are not always pleasant smells (or the brightest colors) either, since they are attracted to numerous kinds of odors, including those of rotting meat for instance. That's why many beetle pollinated plants are brown or dark and not the most pleasant to us. being somewhat clumsy fliers, beetle pollinated flowers tend to be large and easily accessible. Beetles often are also not going after the nectar like other pollinators like bees and butterflies, but looking to eat the pollen that they also then transfer.
     Beetles also pollinate in a different manner than most other pollinators. Many of them actually eat the petals and some pollen, and in so doing, transfer it to other flowers. They often defecate in the flowers while eating there and so are sometimes referred to as "mess and soil" pollinators.

Margined Leatherwing Soldier Beetles mating while pollinating Dogbane

     Some flowers, often from ancient lineages such as magnolias depend on beetles as their primary pollinators. Such flowers are referred to as cantharophilous flowers and beetle pollination is referred to as cantharophily. Some flowers that have beetles as their primary pollinators include some magnolias, lizard's tail, sassafras some palms, cycads, and I believe sessile trillium.
     Beetles also often have more reasons that just a meal to visit flowers. Since they are grouping there already and are attracted to the flower due to smell and/or color, they make a great place to meet other beetles. Beetles often use the blooms as places to mate, sometimes having orgies in the flowers themselves. They are masters of multitasking.

Click Beetles inside a Sessile Trillium flower

     So beetles may not be the most obvious pollinators, or even the prettiest or best, but they are vital for the pollination of many of our plants. They may even have ulterior motives for visiting flowers, to eat the pollen or sex, but they are important, if under appreciated none the less.

Two different beetles on a Swamp Rose.