The Beetles of Bark, Beaches, and Brooks

For any Naturalists there are natural highs and luls in nature throughout the year. The high of spring when the flowers are abundant and organisms at their height of flourishing. Whereas the awkward end of fall when California is super crispy and the rains of winter haven’t injected life into dormant plants and fungi can be a total lul. However Trevor and I created a concoction of activities that maybe, just maybe qualify as a remedy. The only qualifying condition is that you live in Central California. Sorry for everyone else!

It is a two party remedy, part one: tidepooling the King Tides, and part two: bug hunting

In this post I’ll be discussing part two and the different habitats you can explore to look for insects, but more specifically beetles.

  • The four places to look, but are not limited to are:
    • Beaches with driftwood
    • Under bark of a variety of trees
    • Using a UV light to attract insects to you
    • And looking under rocks in small creeks.

But first let’s familiarize ourselves with beetles. To start off Beetles are in the Coleoptera Order with up to 350,000 known species, a number which is growing all the time. This is why they are the largest group of organisms. In the United States alone there are about 30,000. But only about 7,000 have been documented on iNat, so we got work to do folks! 

Luckily my hubby, beetle photographer extraordinaire has gladly contributed all the beetle photos in this post, all of which can be seen on iNaturalist. Thanks Trevor!

Beaches and Driftwood

Beaches might not be the first place you think to look for beetles, and you are not the only one to think that. We’ve helped contribute additional data points for these underrepresented taxa on iNat and BugGuide. Most beaches have driftwood of some form or another, be it logs, plywood, or perhaps a dead animal that looks like a log! Start flipping over whatever you find on your beach and put on our eagle eyes as you watch for movement. Having a small low profile plastic container (think the smallest deli style container) to scoop up anybody interesting. This is a great way to get a closer look, and provide a small area to confine your beetle for a photoshoot. Once finished inspecting the beetle we flip the log back into it’s original position and release our new friend next to the log.

Definitely the Pictured Rove is of the more beautiful beetles we’ve found on a beach, but the rove below is pretty nice too. A well known phenomena is that species of many taxa exhibit different coloration based on its habitat characteristics, and this beauty is no different. Since this rove lives in sand and appears at night to hunt beach hoppers their coloration depends on the sand color. The northern populations are darker due to the more volcanic dominated beaches, whereas the southern populations are lighter, because the sand in southern California is light colored. Neat!

Here we have another Rove Beetle, same family as the prior beetle. They are quite different in coloration, but are both more colorful than the vast majority we find under logs which are often entirely one shade of brown, reddish-brown, dark-brown, really dark brown, and even black.

We love a weevil. Family Curculionidae can be found in almost any terrestrial or freshwater habitat according to American Beetles, but often have narrow list of plants they can consume. I’m not too sure what this fella eats, but there definitely wasn’t any plant material under the piece of driftwood we found him under!

Most people can recall and recognize the big black beetles that find themselves upside down on sidewalks as Darkling Beetles, but this red guy is also a Darkling, a Tenebrionidae. Due to their widespread nature and a few other factors this family is great for scientific studies. I was not aware of this fact, cool! According to the Beetle Bible: American Beetles, they are ideal for understanding “biogeography, ecology and evolutionary systematics.” Why? Well, firstly they are a large and diverse family, so lots of species to work with. Secondly, they can be found munching on fungus, in rainforests, mountain peaks and everywhere in between. Thirdly this group has a fossil record dating back to the Jurassic, holy smokes! Fourth-ly (is that a word?) they affect humans economically, both negatively and positively. The fifth reason, which to any scientist is a wonderful attribute, they are easily collected and do well in captivity. Lastly they possess many interesting morphological characteristics at different life stages to study. I definitely look at Darklings a little different now!

Ooo soemthing dead, yay! Yes we are the weirdos that get excited when we find a dead seal, deer, or whale part, and we have found all three on beaches in the past month-ish. Why would we want to get inches away from a stinky old tendons and rotting flesh? Becuase there could be Dermestid beetles!

These little oval hairy bullets pictured above were found near a stinky winky dinky decaying seal carcass. As scavengers they feed on dried animal parts, as well as plant matter for the large available quantity of protein. But dead beached mammals isn’t the only place to find Dermestes, certain species can be found munching on bee carcasses in bee hives, others are found in bird nests feeding on feathers, or the homes of mammals where old hair is consumed, ummm thats a weird one, even for me. That’s not even the full list, yikes! Fascinating group indeed!

Underneath Bark

Searching for beetles under the bark of downed logs may have been a childhood activity, but HEY we, late twenty somethings do it too! Some key points are to not limit your searching to one type of bark, try all types of trees! Redwood, Bay Laurel, Oak, Alder are just some of the bark we’ve plucked off old logs and taken a peek under. But you’ll find super soaked logs and super dry termite infested logs usually don’t have much activity. BUT, and this is a big BUT, try, try, and try again, you never know what movement will catch your eye, or what abortion in the tree’s natural texture will result in a gorgeous beetle!

Phymaphora belongs to the Family Endomychidae, also known as The Handsome Fungus Beetles. Yup you read that correctly, the Handsome Fungus Beetle. I think they are an handsome couple, don’t you think? We actually have a pair here, a male and female. The dimorphic antennae tell us that, aren’t they crazy! Like boxing gloves! But also a bunch of unwelcomed mites! Eeee! If you look closely you can see the little brown oval bundles of annoyance.

The white fuzzy stuff you see is fungi! Handsome Fungus Beetles are mostly mycophagous, so they eat fungi! More specifically they prefer the “spore and hyphae of microfungi” according to American Beetles Volume 2. Love that for them.

Weevil? Rove Beetle? Who are you?! Trevor’s perseverance paid off and managed to identify it. It is indeed a Rove beetle! But what’s more interesting, is that it’s a iNaturalist first! So it’s the only Tanyrhinus singularis on iNat so far! It is always a pleasure to help add data points and species to the powerful data set that exists on the site. While we may be looking in slightly off the path places, the creek that this cutie was found in is easily accessible along a popular hike in Samuel P. Taylor State Park, near Lagunitas and Point Reyes in Marin County. This shows there are many great species hiding in very popular places!

A fun fact about this species is that they are the only rove with a long rostrum (the beak like snout)! Another piece of interesting anatomy is the pink like blobs near its eyes. Those are ocelli, a light dark sensing simple eye with limited focusing capacities.

Another great name, Genus Salpingus is also known as Hippopotamus Beetles, come on look at that snout! Makes sense! This little snooter tooter was found underneath Red Alder bark near Muddy Hollow in Point Reyes National Seashore. I love his golden colored elytra, fantastique!

Like a couple other beetles in this post, this Namunaria, member of the Colydiinae (Cylindrical Bark Beetles) are fungus eaters. But other members of this subfamily also eat smaller arthropods. But seeing as this one was found under a Bay Laurel Bark in a soft cloud of white fibrilouse mycelium, I think it’s safe to assume he’s a fungi feaster.

We have a clown! A clown beetle! Platysoma’s are in the family of Histeridae, or Clown Beetles. Perhaps you can tell from his mandibles (a mouthpart) that this clown doesn’t mess around at meal times. Indeed, this beetle is predacious. A predatory clown? That’s the premise of a horror movie, truly. But the real horror movie that is currently going on in the L.A. are is the invasion of the Invasive Shot Hole Borer which can attack over 400 species of trees and can take out trees at horrific speeds. Well our beetle here is a “natural enemy of bark beetles” according to American Beetles Volume 1. While I’m not certain our beautiful blue beetle here would eat the invasive ones, perhaps we will one day be praising their taste buds and evolutionary history.

UV Light

A well known technique to attract insects to YOU is setting up a UV light in the evening. Combined with a blank sheet, or wall the critters that show up are fantastic! We have done this in B.C. next to a creek, at a house on the oceans edge, while backpacking, and in the middle of Silicon Valley, so it’s totally possible to set up almost anywhere!

This little golden guy belongs to the family Scarabaeidae, aka the Scarab Beetles. The Genus Aphodius, are known to dwell in the underground dwellings of pocket gophers and prairie dogs. In San Jose where this beetle flew to the UV light California Ground Squirrels are a common sight. So perhaps this beetle popped out of the burrow for an evening.

Don’t you just love the pattern on this weevils elytra? Ah stunning! Weevils are part of the family of leaf beetles, Chrysomelidae. These guys are phytophagous, aka they eat plants, the raw vegans of the insect world, if you may. Adults go for the living plant material, whereas the young larvae munch on leaves or go underground and consume roots or underground stems. Slightly more interesting is that the subfamily our little man belongs to, the Pean and Bean Weevils (Bruchinae) larve live most their lives in a single seed or bean! While the larvae may have a structure to escape to when danger is near, the adults just say “tootles,” pretend death, and drop off the plant. Which if you’ve ever gotten close enough to inspect or photograph a beetle only to have it fall to the ground is truly infuriating. But truly a fantastic technique as I’ve had little to no success finding them again. Gah!

The above fellow, is a gorgeous beetle in the family Eucinetidae, which are commonly known as the Plate-Thigh Beetles. These compact little elliptical shaped friends thrive in detritus or underneath the bark of trees covered in fungus. Plate-Thigh larvae eat fungi and slime mold spores, YUM!

Small Creeks and Brooks

Hunting for beetles and other macro invertebrates in small creeks is a really fun and calming activity. While in university, I volunteered to sort stream macro inverts into orders in a small detached trailer named the “Fish Hut,” which eventually lead to more exciting projects. When overturning rocks these days I do find large stoneflies and other insects, but I also find beetles! It might just take flipping over quite a few rocks, and some chilly hands, but the surprise of finding a new beetle is totally worth it!

Say hello to Dianous nitidulus, which belong to the Family Staphylinidae, also known as Rove Beetles, which we’ve seen many geni of throughout the last couple of months. We most often find them under bark, but these Halloween-y Roves were attached to a rock in a small creek in the Purisima Creek Redwoods Open Space Preserve. Surprisingly there was approximately 15 to 20 beetles, some of which scurried away, others stayed put for a photoshoot. Normally we find five or so of the same beetle in a given spot, rarely this many. Interesting!

This little Postelichus, member of Long-toed Water Beetle Family (Dryopidae) had one of the funniest walks of any beetle recently observed. Imagine this beetle walking extremely slow, but as if he was dodging invisible rocks causing his legs to go quite high off the ground, making his whole body wobble back and forth at little bit. So awkward to watch, and we couldn’t hold back the giggles. But his funny walk makes sense, as Dryopidae adults crawl along a streams bottom, which may include leaf mounds and log piles. Often the case is that larvae are aquatic, and adults terrestrial, but these beetles’s life history is the opposite. Overall a great little find, unexpected and quite interesting. Awesome!

I do believe this beetle has one of the best common names of all beetles, the Water Penny Beetle, Family Psephenidae. How cute! They are about the size of a penny, more oval in shape, and live in riparian areas. The first Eubrianax I found were right outside our Airbnb in Lagunitas, in San Geronimo Creek. Like I keep saying, you don’t have to go far to find really interesting creatures that often go unnoticed.

In Summary

As part of a concerted effort to become a 100% Naturalist, insects are often looked over, but no no no not by me and my partner Mr. Beetle Man.  I hope my description of different habitats and the beetles that occupy them may help you find a new appreciation and interest for all the beautiful beetles out there.

Thank you to all the dedicated identifiers on iNaturalist and Bug Guide that helped identify these beetles, they are the true MVPs! Big Thanks!

5 Comments Add yours

  1. says:

    Excellent work Chloe!! I finally found a quiet moment to sit and enjoy this post. The photos are spectacular and as always, the descriptions are informative and entertaining! It’s so great that you got a beetle for the first time on iNat! Way to go to you both!

    Andrea aka Mom


    1. Thank you so much! I really appreciate your support! Glad you enjoyed the beetles.


  2. patrick stadille says:

    I just stumbled on to this excellent and inspiring blog while looking for sightings of Rhomphea, the Lizard spider. Your time commitment and detailed study is very inspiring. i will show this to my middle school students.
    If you wouldn’t mind, what kind of field camera do you use and where did you find the Rhomphea spiders. I would like to visit there and try to get a better picture of one of them. Thanks. I will start following your other posts.-Pat


    1. Thank you for your kind words Pat! Please do share, much appreciated!
      I use a phone camera (Pixel 2 XL) with a macro lens clip as well as an Olympus TG-6 which gets the best shots.
      The Lizard Spider was swept from evergreen huckleberry!
      Hope that helps, but always happy to answer more questions!


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