CNDDB News Blog

Today we tip our hat to stoneflies, aquatic insects in the order Plecoptera. Stoneflies have a worldwide distribution of over 3,000 species, around 160 of which occur in California. They’re a hugely important part of riparian food webs!

Stoneflies spend the first 1-4 years of their life underwater as nymphs (or naiads). The nymphs require well-oxygenated water and are highly sensitive to pollution. They undergo successive molts, finally emerging from the water for their final molt into adult form when conditions are just right. Adults are typically winged, though not strong fliers, and survive just a few weeks to mate and lay their eggs over water, beginning the cycle again. Ralph and Lisa Cutter’s film, Bugs of the Underworld, includes a beautifully-filmed stonefly’s-eye view of this life cycle.

Of the two stonefly species CNDDB currently tracks, the Lake Tahoe benthic stonefly (Capnia lacustra) is unusual in that it is wingless and spends its entire life cycle underwater, in the deep-water plant beds 30 to 90 meters below the surface of Lake Tahoe. UNR biologist Annie Caires documented an even more surprising adaptation during her studies of the species: live birth! An article in New Scientist shares more about Dr. Caires’ findings. Unfortunately, the studies also showed habitat and population declines for this unique organism.

At least seven of California’s native stonefly species have developed another astonishing behavior: communication by drumming! Certain species signal potential mates by tapping their posterior abdomens on resonant substrates, producing characteristic rhythms. Dedicated researchers have developed special equipment to record these unique drumming signals. John Sandberg, at CDFW’s Aquatic Bioassessment Lab at CSU Chico, takes his miniature stonefly recording studio into the field; his website includes instructions on how to build your own recording setup. If you’re not ready for that level of dedication, don’t worry: the website also has a page of downloadable recordings and videos of drumming for several species.

If you enjoy these sounds as much as we did, stay tuned for Dr. Sandberg and coauthor Luke Myers’ upcoming manuscript summarizing the known Nearctic signal description from 1977 to 2015. The manuscript, to be published in the online journal Illiesia, will provide a starting point for all future research.

Let the incredible sounds and remarkable behaviors of these tiny animals be a reminder to us all to pay more attention to the insects around us! See the Special Animals List on our website for a complete list of the insects and other invertebrates we track. And don’t forget to report your observations on our Online Field Survey Form!

Live birth of Capnia lacustra nymph (Credit: Annie Caires)

Wingless, aquatic adults of Capnia lacustra (credit: Annie Caires)

Big Bear Lake is a beautiful mountain lake in Southern California and a popular year-round resort destination. What many visitors to Big Bear Lake don’t realize is that this area is home to a relict Ice Age habitat type called pebble plains; the only place in the world where this ecosystem occurs. Pebble plains are flat open areas left over from when glaciers receded in the Pleistocene age and are named for the quartzite pebbles that are pushed to the surface of the clay soil by frost heaving. Pebble plains support a unique plant community comprised of 17 protected plant taxa and 4 rare butterflies. The plants that occupy the pebble plains are sometimes referred to as “belly plants” due to their miniature stature, but once you get close to them you can see that they are just as beautiful as their larger-sized counterparts.

Pebble plains are extremely fragile and the endemic plants are very slow growing so any damage to the soil or plants can be devastating to the ecosystem. A large portion of pebble plain habitat was lost when Big Bear Lake was created in the late 1880s and early 1900s, with additional habitat lost to development around the lake in the subsequent decades. Besides development on private lands, one of the biggest threats to the remaining pebble plain habitat is high-impact recreational activities, especially off-road vehicles. Agencies and conservation organizations have made efforts to curtail off-road vehicle use through use of barriers, fencing, and signage but trespassing still occurs.

March through June are great times to visit the pebble plains, see beautiful wildflowers, and experience this unique ecosystem that only California has to offer. The California Department of Fish and Wildlife’s Baldwin Lake Ecological Reserve has a self-guided interpretive trail and visitor center that allows hikers to experience the pebble plains. The reserve is currently closed due to COVID-19 concerns but keep an eye out for its reopening in the coming weeks.

The blank stare of foothill yellow-legged frog (Rana boylii) as it rests in a stream. What is it thinking about?

Today we celebrate members of the order Anura which is composed of frogs and toads. What’s not to love about our froggy friends? These moist goblins have large protruding eyes and a wide mouth that make them expressive, and some would describe them as “ugly cute.”

Perhaps the most remarkable life history feature of frogs and toads is their metamorphic life cycle. They start off as water dependent lifeforms, tadpoles, that have a tail for swimming and gills for breathing. The tadpoles transform into their adult form, growing lungs and limbs that enable them to survive out of the water.

Unfortunately, living a double life does not make them impervious. Amphibians are seen as “canaries in the coal mine,” indicators of environmental health. Global amphibian populations are in decline, and about one third of species are believed to be threatened. In some cases, they are even disappearing from protected areas without clear explanations. The exact cause of the decline is unknown but thought to be a combination of diverse factors that include habitat destruction, introduced species, chemical contaminants, disease, and climate change.

California is home to a number of frog species, so keep an eye out for our froggy friends next time you find yourself at a pond or stream. The CNDDB tracks 16 species of frogs or toads. Help us keep track of them by submitting your observations to us!

A frog fan explores a pond.