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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 · 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 · 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
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 · 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 · 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
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
What a beautiful insect, and posing so nicely for this photo!
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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 · 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 · 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 · 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
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
#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
#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
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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John Carlson @johncarlson.bsky.social · 15/08/2025
I’m not particularly superstitious but on days that I do especially high risk protocols in the allergy clinic I wear ties that have ladybugs, a symbol of good luck. Today I wore my ladybuggiest tie and am pleased to report that things went well!
A shiny red beetle with five visible black spots and a black pronotum and head with smaller white spots is sitting on a green leave that as tufts of white fluff on it. Looking closely you can see a small brown aphid being eaten.
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John Carlson @johncarlson.bsky.social · 08/08/2025
We had one potential case of locally acquired Chagas’ disease in New Orleans: infected bugs were feeding indoors on someone then diagnosed with infection. Even then it’s uncertain if she got it here vs earlier in life in another country. How do dogs handle it? pmc.ncbi.nlm.nih.gov/articles/PMC...
pmc.ncbi.nlm.nih.gov
Autochthonous Transmission of Trypanosoma cruzi, Louisiana
Autochthonous transmission of the Chagas disease parasite, Trypanosoma cruzi, was detected in a patient in rural New Orleans, Louisiana. The patient had positive test results from 2 serologic tests an...
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John Carlson @johncarlson.bsky.social · 08/08/2025
Babesia is a tricky infection to diagnose because the symptoms are so general: Fever and feeling sick. As the climate warms, exposure to this ticks increases, along with the many, many pathogens that they transmit.
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John Carlson @johncarlson.bsky.social · 08/08/2025
Thankfully transmission of T cruzi to humans is rare in the US because the species of kissing bugs we have don’t feed on people very often, and when they do, usually don’t defecate while feeding (needed to get the Protozoa into the bite wound). But cases do happen and are probably under-diagnosed.
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John Carlson @johncarlson.bsky.social · 07/08/2025
Becoming allergic to your research organism is miserable! Read this great article to hear about examples of allergies to butterflies, leeches, snakes and more that develop in people that study these creatures.
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John Carlson @johncarlson.bsky.social · 07/08/2025
Our hospital has therapy dogs come and visit patients, each dog with their own hospital badge. This rarely seen Cryptocephalus cupressi is a case-bearing leaf beetle, found just outside the hospital entrance. It feels like a therapy beetle but it didn’t have a badge so I didn’t let it inside
A beetle seen in profile. The background color is creamy white with large brown splotches on the pronotum and darker brown splotches on the elytra. While the pronotum is smooth, the elytra are dotted with small dark pits. About half of the overall color is the light cream of the background and the other half is brown because there are so many splotches and pits.
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John Carlson @johncarlson.bsky.social · 07/08/2025
A Clavate Tortoise Beetle, Helocassis clavata, pokes its antennae out into the dangerous world.
Looking down into an oval insect that is shaped like the domed shell of a turtle. The front and sides have transparent sections with the middle of the shell is a shiny brown. The shell has a wrinkled texture. At the leading edge you can make out two tiny feet and two long segmented antennae poking out. The insect is standing on a bright green leaf.
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John Carlson @johncarlson.bsky.social · 06/08/2025
A sweet sweat bee gathering pollen
A black bee is in the middle of a bright yellow flower. Looking down to the bee you can see yellow pollen stuck to the hairs on the legs such that the margins of each leg looks fuzzy yellow.
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Reposted by John Carlson
Alli’s Nature Journal @anaturejournal.bsky.social · 06/08/2025
Black-waved Flannel Moth Caterpillar. A whimsical encounter! Best to keep distance if you cross paths because under those wispy, white hairs are venomous spikes that will sting! #MegalopygeCrispata #bugsky
A flannel moth white caterpillar with extra long, wispy white hairs. Best to keep a distance from them! caterpillars invertebrates moths woodlands nature blackwavedflannelmoth
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John Carlson @johncarlson.bsky.social · 05/08/2025
She thinks I’m sweet... Aedes triseriatus on my leg.
A dark brown mosquito is on a slightly hairy leg. This view looks onto the face and thorax of the insect vent to probe its proboscis into my skin. The brown legs fold out from the sides of the thorax with the hind legs lifted into the air behind the insect. Because the thorax and head are bent down, the wings and abdomen are running away from the plane of focus and get blurry in the distance
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John Carlson @johncarlson.bsky.social · 04/08/2025
This tiny robber fly was busy snacking, so was able to creep up pretty close to get this photo.
A fly seen in profile, head up and abdomen down with legs projecting to the left, clinging onto a stem. The wings are folded over the back. The eyes are a dark red with hundreds of facets. The mouth has a small insect out of focus being eaten.
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John Carlson @johncarlson.bsky.social · 04/08/2025
A Green Coverworm Moth landed on a red flower just long enough for a photo last night. Nice red eyes to match the red flower. 😍
Looking down onto a light brown moth that is just off center of a frilly pearled red flower last looking closely the two round eyes of the moth are dark red.
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John Carlson @johncarlson.bsky.social · 02/08/2025
Paper wasps are not particularly aggressive, but they do sometimes build nests that get easily disturbed, eg this nest in the hollow portion of a metal gate. When the gate gets opened or closed the workers fly out and sting anyone that might be a danger to the nest.
The center of the photo is an area black in shadow while around is bright and over exposed because of harsh sunlight. Within the dark hollow there are two paper wasps visible with bright yellow markings on an otherwise back insect making it stand out within the shadow. Looking closely you can make out the pattern of the brown open comb nest of the wasps, but just barely because the shadowed area is so dark.
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John Carlson @johncarlson.bsky.social · 01/08/2025
Most Southern Flannel Moth caterpillars are killed by parasitic flies or wasps before reaching their fluffy adult form. This year I’ve seen far more adults than any other year. If the flies and wasps don’t pick up it might mean 2026 will be a bad year for caterpillar stings. 🫣
A fluffy moth is seen in profile on a white wall, head facing down. The front fluff is orange. In the middle the fluff has a lot of black with some streaks of white on the fluffy wings. The backs of the wings are a fluffy tan.
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John Carlson @johncarlson.bsky.social · 31/07/2025
A longhorn beetle, Dectes texanus, sheltering under a leaf along the Mississippi River flood plane this past weekend.
Looking down onto the back of a gray beetle that has a soft appearance from gray scales that cover it. It has very long antennae, as long as the length of the beetle, curving out from the head in gentle arcs that end up pointing laterally  to the right and left of the beetle. The beetle is on a green leaf that makes up the entire background of the photo
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John Carlson @johncarlson.bsky.social · 30/07/2025
Passionflower vines are native plants that have beautiful flowers, and are the food for the striking Gulf Fritillary caterpillars that grow up to be gorgeous butterflies. Who gives out the awards for Best Looking Plant/Caterpillar/Butterfly Combination? I’d like to make a nomination.
An orange caterpillar with rows of black branching spikes from head to posterior  is seen in profile, sitting atop a green vine half the width of the caterpillar. Out of focus you can make out leaves that have been chewed up by the caterpillar A velvety orange butterfly has delicate black marking and three small silver spots on the forwings. The body is also a soft orange, with silvery silvery spots in the anterior thorax and head.
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John Carlson @johncarlson.bsky.social · 30/07/2025
Fascinating! This treehopper was probably using its helmet to sense my presence through electrostatic cues on Prince Edward Island last summer. What an incredible way to sense the world!
A dark brown insect is seen in profile, sitting on a light green plant stem. The only real color variation of the bug is a slightly reddish eye. The shape of the bug is thorn-like, with a cone projected up above the head, but the tip is blunt, not sharp. With the light turned up to catch some of the fine details of the insect you can also see that the plant stem has fine white hairs that give it a soft texture.
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John Carlson @johncarlson.bsky.social · 29/07/2025
A Leafcutter bee sipping nectar under a blindingly bright summer sun.
 Black bee with white fuzzy stripes on the abdomen is perched on the yellow tuft as the center of a flower that has white petals. The oblique view shows the head close up with eyes that are very light green in color. There is a little tongue sticking from the bottom of the head into the middle of the yellow florets
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John Carlson @johncarlson.bsky.social · 28/07/2025
A Needham's Skimmer dragonfly overlooking Bayou St John yesterday afternoon.
A reddish golden dragonfly is seen in profile, with its little legs grasping onto a dry brown reed. There are several green reeds out of focus behind it and the background is a blurry rippling water that is green and blue reflecting light from the sky and homes on the far bank of the bayou.
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John Carlson @johncarlson.bsky.social · 28/07/2025
A Two-spotted Longhorn Bee collecting pollen across from Bayou St John yesterday.
A large black bee is on a bright yellow flower that has a rim or red in the middle. The wings are folded on the back with textured veins making a wrinkled texture to the bee’s back.
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John Carlson @johncarlson.bsky.social · 28/07/2025
A Common Thread-waisted wasp, Ammophila procera, drinking nectar near Bayou St John this afternoon.
A flower has six bright yellow flowers that become read towards the central part has a wasp on it. The wasp is as long as the flower is wide. It is nearly all black with a very skinny long “waist” extending from the thorax that becomes reddish in color before a bulbous black end to the abdomen.
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John Carlson @johncarlson.bsky.social · 27/07/2025
Along the Mississippi River just south of the New Orleans Airport, A Megachile bee lifts into the air
A small fluffy bee is generally brown, but has the dark bands of the abdomen that gives it a striped appearance. Its back two left legs are still touching the frogfruit blossom rimmed with white florets otherwise it appears suspended in the air.
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John Carlson @johncarlson.bsky.social · 26/07/2025
A Painted Coreid bug in the Mississippi River flood plane in St Rose, Louisiana, a short drive upriver from New Orleans.
A black bug is face down on a blade of grass. It is all black except for a reddish stripe on the thorax and there is also a hint of the same color on the lateral aspect of the abdomen
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John Carlson @johncarlson.bsky.social · 24/07/2025
A checkered skipper resting on a little frogfruit flower in the 9th ward, New Orleans.
A white butterfly with brown markings is standing on a little cluster of flowers that is only as wide as the insect’s thorax. The round black eye is in contrast to the fluffy white of the head.
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John Carlson @johncarlson.bsky.social · 23/07/2025
I’m not sure how to crop photos of Orthoptera with crazy long antennae. It feels rude to cut them off, but my goodness it means making the rest of the insect a smaller piece of the photo. Here is a Restless Bush Cricket to demonstrate the conundrum.
A brown cricked with long back legs is sitting on leaves of a plant, situated in the bottom left hand corner of the photo. Off of the head you can see a very long thin antenna poured to the top left of the photo. It’s skinny but the light color of the antenna contrasts enough with the dark background that you can see it to the end, perhaps three times as long as the length of the cricket’s body
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