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John Carlson

@johncarlson.bsky.social
1.5K followers 1.2K following 769 posts

Allergist/Immunologist, Entomologist/Parasitologist, Pediatric Residency Director at Ochsner in New Orleans. Research, MedEd, Insect macrophotography

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John Carlson @johncarlson.bsky.social · 06/08/2026
Yesterday I heard about a third fatal cases of venom-induced anaphylaxis this year. It’s especially sad because reactions are preventable with desensitization. As in this case, epinephrine does not always work, so desensitization is really important for anyone with prior anaphylaxis from a sting.
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John Carlson @johncarlson.bsky.social · 27/11/2025
Decaying vegetation in stagnant water definitely sounds like rat tailed maggots. Very strange looking creatures. The adults are really nice looking, many bee/wasp mimics.
A dark black shiny fly with thin yellow stripes on the abdomen is sitting on a white flower
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John Carlson @johncarlson.bsky.social · 26/11/2025
I’m going to guess that they’re maggots of some kind. Rat tailed maggots are the closest that I’ve seen, but I’m really not sure if those long trailing parts are a breathing siphon or just trailing goop? Did they come out of water, or at least mud, with high organic content?
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John Carlson @johncarlson.bsky.social · 26/11/2025
Inconsistently! Fall is my busy season with residency interviews so spotty presence on social media until February. But I am checking in on Bluesky every few days
Looking down on the back side of an Aedes aegypti with belly full of blood, otherwise black with white lines splashed about the insect.
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John Carlson @johncarlson.bsky.social · 26/11/2025
The Wedge-shaped Beetle, Macrosiagon cruenta, ambling around on flowers near the Mississippi River
A black beetle with reddish color that takes up the anterior half of the elytra is hanging up-side-down on a cluster of whitish pink flowers.
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John Carlson @johncarlson.bsky.social · 29/09/2025
Aren’t butterflies (and other small wondrous creatures) great reminders that there is beauty in the world? It doesn’t take away from the very hard things going on, but does provide a counterbalance that I find helpful. 💛🖤💛
In the foreground are stems rising up from below the frame of the photo, each bearing clusters of bright pink flowers. There is a black and yellow butterfly perched near the top of one, drinking from on of the flowers. In the blurry background you see the Mississippi River, a green forest on the other side and a sky that is blue but with a lot of fluffy clouds.
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John Carlson @johncarlson.bsky.social · 27/09/2025
Late September is when green leaves turn into yellow butterflies here in New Orleans.
A bright yellow butterfly is seen in profile sitting on a pale yellow flower. The sun’s angle sets off the texture of the wings with shadows under the veins.
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John Carlson @johncarlson.bsky.social · 27/09/2025
😂 Calling a beetle “pale legged” is bound to make it feel judged!
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John Carlson @johncarlson.bsky.social · 27/09/2025
A pale-legged flea beetle, Lysathia ludoviciana, looking contemplative at the leaf’s edge.
A black beetle with a faint greenish hue is at the edge of a bright green leaf. You can see plant hairs on the bottom of the leaf giving you the sense that this is really zoomed in to a tiny beetle. The beetle is peering over the edge of the leaf.
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John Carlson @johncarlson.bsky.social · 22/09/2025
I don’t often plan my trips out to the batture and arrive out there midday under the blasting heat of the sun. It is so hot! But- the lighting is great!
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John Carlson @johncarlson.bsky.social · 22/09/2025
Agreed!
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John Carlson @johncarlson.bsky.social · 22/09/2025
They really are delightful creatures
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John Carlson @johncarlson.bsky.social · 22/09/2025
Thanks!
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John Carlson @johncarlson.bsky.social · 21/09/2025
The Bronzed Tiger Beetles (Cicindela repanda) scampering along the Mississippi River beaches have subtle iridescent colors when you look closely.
A brown beetle stands on sand. There are white curly lines on the elytra scribbled in from the lateral margins. When you look closely at the brown parts of the elytra, thorax and head you see red and green iridescent sparkles
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John Carlson @johncarlson.bsky.social · 21/09/2025
😂 I can imagine a taxonomist of long ago, starting to have trouble with their eyesight, sniffing specimens to tell the species apart.
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John Carlson @johncarlson.bsky.social · 21/09/2025
They are pretty wild!
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John Carlson @johncarlson.bsky.social · 20/09/2025
A Hibiscus Scentless Plant Bug, Niesthrea louisianica, on the edge of a hibiscus flower in the Mississippi River flood plane
A bug with an orange head and body with speckles of white, pink, and maroon, is standing on the edge of a flower petal that is light pink in color. The translucent wings folded over the back of the bug have a hint of orange to them. It is a bit gaudy.
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John Carlson @johncarlson.bsky.social · 19/09/2025
A photo from the first Bug Walk in 2013. I don’t always wear a tie.
A man with brown boots, khaki pants, tan shirt, and greenish hat is holding an aerial sweep net, standing on a wooden walkway in the woods next to a first with yellow shirt, blue shorts and gray boots. She looks happy.
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John Carlson @johncarlson.bsky.social · 19/09/2025
Despite the unusually dry weather we had a successful Bug Walk in Audubon Park and nearby neighborhood to find insects of medical (and non medical) relevance. This year we had folks download @inaturalist.bsky.social (or Seek) to practice documenting the biota in the city.
A group of people are standing in front of a fountain with a statue of a woman at the top, seen above the heads of the people standing in front of it. The oldest of the group is a man to the far left wearing brown boots, green pants, a tan shirt, tan hat, and brown tie. That’s me! The Allergy Fellow in the bottom right hand corner is holding an aerial sweep net. A huge live oak tree is in the background
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John Carlson @johncarlson.bsky.social · 19/09/2025
I don’t know what the pokey bits in the back are for- sorry!
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John Carlson @johncarlson.bsky.social · 19/09/2025
What a beautiful insect, and posing so nicely for this photo!
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John Carlson @johncarlson.bsky.social · 16/09/2025
That’s an aphid- but they are notoriously difficult to identify down to species.
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John Carlson @johncarlson.bsky.social · 15/09/2025
It really is wonderful to see how the ecosystems change over time. Adding in those native plants is going to support some incredible creatures!
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John Carlson @johncarlson.bsky.social · 15/09/2025
Looking back I didn’t upload any photos in 2013; it was when we did a repeat BioBlitz at Jean Lafitte 2016 that I brought a group of Allergy/Immunology fellows and took my first photo. Incidentally that was the start of my annual Allergy Bug walk for fellows. How it started / How it’s going
A wasp with red head and thorax, black abdomen and wings l, and yellow legs is face-down on a green leafA wasp with red head and thorax, black abdomen and wings, and yellow legs is head down on a filmy translucent web with numerous white caterpillars within the nest. Most of these are blurry being inside the web but one has been pulled out and the wasp is preparing it to take back to its own nest
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John Carlson @johncarlson.bsky.social · 14/09/2025
My first post on @inaturalist.bsky.social was a Metric Paper Wasp (my favorite paper wasp) as part of a National Geographic supported, invertebrate-focused BioBlitz in Jean Lafitte National Park in 2013. And now it is my 20,000th post also!
A screen shot from the iNaturalist app. In the top left is a tiny photo of me with my son. Below that you can see the species number, 20,000 and to the right on the same line it says 3,250 species. You can see the three most recent posts, a metric paper wasp at the top, the a North American spit-throated grasshopper and lastly a sleepy orange butterfly.
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John Carlson @johncarlson.bsky.social · 14/09/2025
It’s very dry here in New Orleans; plants are crisping up and the insect activity is way down. An exception is this wasp, clamoring over flowers, perhaps using nectar for hydration
A wasp is standing on the backside of a stem with little white flowers on it. The flowers are so little that we can see most of the underside of the wasp. The abdomen is light brown with yellow stripes, the thorax black with yellow legs grasping onto the plants, and most clearly you can see the face of the wasp that is light yellow with shiny brown eyes on each side and antennae curing in front of it.
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John Carlson @johncarlson.bsky.social · 13/09/2025
I finally got a flash for my camera so that I could increase shutter speed. My first subject was one of the frenetically bumbling bumblebees crashing into flower after flower. I didn’t get a great photo of the bee but you can see the pollen floating away from the flower which is really interesting
A photo of a bee hanging down from the bottom of a white flower. It’s very fuzzy with black and yellow fur. Its tongue is probing into the flower. Off to the left of the bee are little white specks floating in the air, seen on the bah round of blurry green vegetation
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John Carlson @johncarlson.bsky.social · 12/09/2025
A pretty Thread-waisted #wasp meandering through the vegetation at Bayou Savage in New Orleans
An insect seen in near-profile. Its abdomen is a reddish brown. Thorax is black and yellow but mostly covered by translucent wings with dark veins folded over the back. The head has large black eyes and a pale yellow face. The black legs are helping to crawl across a background of grass that is green and tan.
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John Carlson @johncarlson.bsky.social · 11/09/2025
A Question Mark #Butterfly sipping Mississippi River water on the sandy shores under an exceptionally bright sun this past weekend
A brown butterfly seen in profile on a rough patch of sand. The background of the photo is mostly white, with the bright sun causing the photo to be over exposed.
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John Carlson @johncarlson.bsky.social · 11/09/2025
There is some really fascinating research on this that I learned about reading The Laws of Connection by @davidarobson.bsky.social with solutions other than brain surgery!
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John Carlson @johncarlson.bsky.social · 08/09/2025
A Four-spotted Pennant #Dragonfly perches next to the Mississippi River as it bends around the city of New Orleans.
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John Carlson @johncarlson.bsky.social · 08/09/2025
They are incredible creature!
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John Carlson @johncarlson.bsky.social · 06/09/2025
Hang in there.
A cicada is upside down hanging from a braided metal wire. In the blurry background is a parking lot with cars at the bottom of the image, and above that is a blue sky mostly covered in soft clouds that are white and gray
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John Carlson @johncarlson.bsky.social · 02/09/2025
I wish I knew! It is definitely a very fancy design… but if hairs? And what function do they serve? There is a whole tiny world that we know so little about!
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John Carlson @johncarlson.bsky.social · 31/08/2025
Exploring Bayou Savage in New Orleans East I found this weevil posing on the beautiful backdrop of a flowering Saltmarsh Mallow.
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John Carlson @johncarlson.bsky.social · 24/08/2025
This afternoon I discovered that my boots are no longer waterproof but that they remain mosquito proof. Tested simultaneously by water in the Mississippi River flood plane and by several Psorophora columbiae mosquitoes that live there.
A macro photo looking into the face of a mosquito with dark brown shimmery eyes, head and thorax that are various specked colors from dark brown to white, legs sticking out to either side with similar spatter colors of brown and white. It is sitting on a brown fabric driving its proboscis into the fabric.
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John Carlson @johncarlson.bsky.social · 22/08/2025
An Anchor Stink Bug instantly before it took flight. Photo taken last weekend on the shores of the Mississippi River.
A close up photo of a black insect with orange spots seen in profile. Its head with long pointy proboscis is pointed downwards relative to the rest of the body. It is sitting awkwardly on the small top leaves of a plant.
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John Carlson @johncarlson.bsky.social · 22/08/2025
That’s a good thought. Fungal infections can be itchy (ring worm for sure, and rare reports of sporotrichosis). I’ll add that to my list!
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John Carlson @johncarlson.bsky.social · 22/08/2025
Thanks!
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John Carlson @johncarlson.bsky.social · 22/08/2025
When I see the kids in person, I do give them a pep talk about how amazing it was to experience such an incredible insect. It usually works!
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John Carlson @johncarlson.bsky.social · 22/08/2025
Of all the crazy things going on in the world, I would not have expected people to engage in more ant smuggling. That’s a whole new kind of ne’re-do-well!
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John Carlson @johncarlson.bsky.social · 22/08/2025
Two large halictid #bees (I think Nomia nortoni) enjoying some midday sun.
Looking down onto a plant with radiating light green leaves. On two of the leaves there are black bees with bright white abdominal stripes. They are both facing towards the center of the plant.
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John Carlson @johncarlson.bsky.social · 22/08/2025
Patients with multiple delayed-type allergic reactions are most often reacting to mosquitoes, bedbugs or fleas. There are others but these three are common. Mosquito reactions tend to be cross-reactive at the genus level, so these could still be less common mosquito species, or fleas.
A photo of a flea under the microscope showing long hairy back legs and smaller middle and front legs. A bullet-shaped head points to the right, with very dark bands of thorax and then abdomen to the left. This is a low quality, somewhat grainy photo
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John Carlson @johncarlson.bsky.social · 22/08/2025
#EntomologyConsult: a patient has an enlarging, progressively itchy, edematous area on her forearm with similar lesions on skin not typically covered by clothes. Bedbug inspection found no insects. This is atypical of her mosquito bite reactions. What could have caused this?
Mostly out-of-focus photo of an arm that has a somewhat reddish swollen part in the middle of the frame. Within the center there is some very mild tearing of the skin from scratching.
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John Carlson @johncarlson.bsky.social · 21/08/2025
Velvet Ants are a group of wasps in a separate family from true ants. Flightless females scurry along the ground, and may use bright aposematic coloration to warn would-be predators (and curious children) that they have painful (but not dangerous) venom. Treat with ice, hugs, kisses and stickers
A red insect with black legs, black horizontal stripe across the abdomen and black horizontal stripe at anterior abdomen is on sandy ground. The fine, dense hairs make it look very soft, like velvet.
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John Carlson @johncarlson.bsky.social · 21/08/2025
#EntomologyConsult: a child was stung on the hand by an ant, but with pain beyond what is expected for a typical fire ant sting. Is this species more dangerous? My answer ⬇️
A dead insect curled up. It is red with black markings, slightly out of focus. You can make out the long thin stinger protruding from the tip of the abdomen.
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Reposted by John Carlson
Jagriti Paul @pauljagriti.bsky.social · 18/08/2025
Had the privilege of leading Pediatric Grand Rounds at Ochsner Children’s last week. Presented a preterm case that turned out to be a real zebra—a high-grade bowel obstruction from congenital adhesive bands in a 33-weeker. Not your “bread & butter” NICU day. #NICU #Neonatology #Pediatrics
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John Carlson @johncarlson.bsky.social · 18/08/2025
Hibiscus pollen makes bees look very fancy!
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John Carlson @johncarlson.bsky.social · 18/08/2025
A soldier #fly, Hoplitimyia mutabilis, resting under the hot summer sun near the Mississippi River
A profile view of a black fly, with yellow bands on the posterior abdomen, orangish wings folded over the back, and eyes that are dark green striped with black lines.
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John Carlson @johncarlson.bsky.social · 16/08/2025
Happy bees! I wonder if Hibiscus flowers may be too much of a good thing for bees. They can get plastered with the sticky balls of pollen! Hibiscus plants grow wild along the Mississippi flood plane and I can spend a lot of time watching these goofy insects coating themselves in the copious pollen.
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