This is neat: Robin Sloan is rewriting his 2009 short story, Mr. Penumbra’s 24-Hour Bookstore. “The interplay between books and technology has changed since I wrote them…but also that I have become a different writer, and a better one.”

Roselle (Hibiscus sabdariffa), also known as Florida cranberry, Jamaican sorrel, or red sorrel, is a vibrant, heat-loving annual that thrives in Florida’s warm climate and delivers both ornamental beauty and impressive health benefits.

Native to West and Central Africa, roselle is perfectly adapted to hot, sunny conditions and grows readily throughout Florida, especially in USDA hardiness zones 9–10. It tolerates high summer temperatures and even drought once established, making it an excellent choice for low-input, sustainable gardens.

• Planting time: Sow seeds or set out transplants in April–May (or again in August for a fall harvest).

• Growth habit: Plants reach 5–7 feet tall, with reddish-green lobed leaves and striking yellow flowers with dark centers.

• Harvest window: Calyces (the fleshy red cups beneath the flowers) mature in October–November; harvest before frost or temperatures drop below 40°F.

• Yield: A single healthy plant can produce up to 12–16 pounds of calyces with proper care.

  Edible and Medicinal Uses

  The star of roselle is its tart, cranberry-like calyx, used fresh or dried for the following:

  • Jams, jellies, and sauces (a Florida “cranberry” sauce)

  • Refreshing teas, cordials, and festive holiday drinks

  • Flavoring for pies, crisps, and smoothies

  • Dried calyces for long-term storage and year-round use

  Leaves can be eaten cooked as greens or added raw to salads for a tangy zing, while seeds are high in protein and can be roasted or ground into soups.

  

  Health Benefits Backed by Science

  Roselle is more than just a pretty garden plant—it’s a nutrient-dense superfood with a growing body of research supporting its wellness potential:

  • Rich in antioxidants: Packed with anthocyanins (which give it its deep red color), vitamin C, polyphenols, and organic acids that combat oxidative stress.

  • Supports heart health: Multiple studies show roselle tea or extract can help lower blood pressure, reduce LDL (“bad”) cholesterol, and improve blood vessel function.

  • Anti-inflammatory effects: Recent reviews highlight roselle’s ability to inhibit inflammatory markers, potentially easing symptoms of arthritis and other chronic inflammatory conditions.

  • Blood sugar regulation: Emerging evidence suggests roselle may improve insulin sensitivity and help manage blood glucose levels—promising for those with prediabetes or type 2 diabetes.

  • Digestive and immune support: High in fiber and prebiotics, roselle promotes gut health; its vitamin C and A content bolsters immune function.

  • Potential anticancer properties: Laboratory studies indicate roselle extracts may slow tumor growth and inhibit cancer cell proliferation, though more human trials are needed.

  Growing Tips for Florida Gardeners

  • Sun: Full sun is essential—roselle won’t thrive in shade.

  • Soil: Well-drained soil is key; amend with compost if needed.

  • Water: Water during dry spells, but avoid overwatering.

  • Pests: Watch for root-knot nematodes; practice crop rotation to reduce buildup.

  • Variety: ‘Victor’ is a proven performer in South Florida.

  Final Thoughts

  Roselle is a resilient, multipurpose plant that fits seamlessly into Florida’s subtropical gardens while offering a tart, cranberry-like harvest and an impressive portfolio of health-promoting compounds. Whether you’re brewing a refreshing tea, making a holiday drink, or exploring its anti-inflammatory and cardioprotective potential, roselle is a worthy addition to any heat-tolerant edible landscape.

…and Florida residents can get the wasps free.

Tamarixia radiata is a roughly 1-millimeter parasitoid wasp that kills the Asian citrus psyllid (Diaphorina citri), the insect that spreads the bacterium behind citrus greening (HLB). It won’t cure an infected tree, but by suppressing the psyllid it slows the disease. As you will find here, Florida residents can request the wasps for free!

A Very Small Ally with a Very Big Job

Meet one of the smallest and hardest-working allies in Florida’s and California citrus story. Tamarixia radiata is a gnat-sized parasitoid wasp, no bigger than the head of a pin, , and it has a single mission: hunting down the Asian citrus psyllid, the insect that spreads devastating citrus greening disease. In this blog, we’ll walk through where this wasp came from, why it matters to your dooryard citrus, what the research says, and how you can get your own vial.

Figure 1. An adult Tamarixia radiata magnified under a lab microscope. At roughly 1 mm long, this wasp is easy to miss but hard at work. Credit: Edwin Gutierrez-Rodriguez, UF/IFAS.

 A Little History: How a Wasp Became Florida’s Ally

The trouble began in 1998, when the Asian citrus psyllid (Diaphorina citri) was first discovered in Palm Beach County, Florida (The Discovery of Huanglongbing in Florida), feeding on orange jasmine. The psyllid itself is a problem, but the real danger is what it carries: the bacterium that causes Huanglongbing (HLB), better known as citrus greening, one of the most destructive citrus diseases in the world.

Scientists needed a natural enemy. In October 1998, researchers imported Tamarixia radiata from Taiwan and Vietnam into a high-security quarantine at the Florida Department of Agriculture and Consumer Services (FDACS) Division of plant Industry in Gainesville.

To keep the disease out, no plant material or psyllid hosts came with them, and the wasps were reared on psyllids raised on orange jasmine. Over more than a dozen generations, every colony was tested to be sure it was clean.

Permission to release came in 1999. The first Tamarixia were set free near Fort Pierce. It was the start of Florida’s classical biological control program against the psyllid, and the wasp has since spread and worked across the state…read more.

Did you know?

The wasp had already proven itself overseas. According to the EPPO Global Database, T. radiata may be present on all continents except Antarctica. Over the two time periods (2030 and 2050), T. radiata is projected to expand its known distribution into new climatic regions, mainly due to increases in the mean temperature of the coldest quarter in those regions. EPPO Global Database

The word parasitoid is different from parasite, which you are probably more familiar with.

A parasite generally feeds on a host without killing it. A parasitoid, like Tamarixia, ultimately kills its host as part of completing its life cycle. And this one is remarkably specific: it does not attack any insect other than the Asian citrus psyllid, making it a very safe, targeted tool for your yard.

A two-front attack

This little wasp fights the psyllid in two ways at once:

• Parasitism: A female lays an egg beneath a psyllid nymph. The larva hatches and feeds on that nymph from the outside (an “ectoparasitoid”), killing it before emerging as a new adult wasp.
• Host feeding: The female also punctures psyllid nymphs with her ovipositor and feeds on the fluids that ooze out. This protein lets her lay more eggs and kills the psyllid directly.

Add it up, and a single female Tamarixia can kill up to 500 psyllids in her lifetime through the combination of host feeding and parasitism. Not bad for an insect you can barely see.

Why It Matters for our Citrus

Citrus greening has no cure yet! Infected trees show blotchy, mottled yellow leaves, heavy leaf drop, dieback, and small, misshapen, bitter fruit. Because the bacterium is spread by the psyllid, controlling the psyllid is one of the best ways a homeowner can slow the disease, for their own trees and their neighbors’ trees, too.

Commercial groves manage psyllids as part of a larger integrated program. But backyard and dooryard citrus often go untreated, and those trees can quietly build up large psyllid populations that spread greening through the neighborhood. That is exactly the gap biological control is designed to fill: it is environmentally sound, needs no spraying, and keeps working on its own.

What the Research Says

Florida has studied this wasp closely, and the honest picture is one of a helpful, but not magic, tool.

UF/IFAS and FDACS research (Qureshi et al. 2009) found parasitism rates in Florida averaging under 20% in spring and summer, rising to roughly 39–56% in the fall. Some earlier Florida surveys recorded much lower rates, showing how variable results can be across sites and seasons (Especially summer).

Elsewhere, results have been even stronger: parasitism rates of 79–88% have been reported in Puerto Rico, and Brazilian mass-rearing studies have recorded rates of 72–89%. Lab work also points to the wasp’s “sweet spot”: Tamarixia develops and survives best at about 26–30 °C, and does better on older psyllid nymphs.

The takeaway from UF/IFAS science is consistent: Tamarixia radiata can meaningfully suppress psyllid populations and is considered the most effective natural enemy of the Asian citrus psyllid, especially as one part of an integrated approach. It works best when released widely and repeatedly, which is where you come in.

The numbers at a glance

• Up to 500 psyllids potentially killed by one female wasp (host feeding + parasitism)

• 39–56% parasitism in Florida in fall; higher in some regions

• 26–30 °C is the ideal temperature range for the wasp

• Attacks only the Asian citrus psyllid, no other insects

How to Get Your Own Tamarixia

Since 1999, these wasps have been released in research and commercial groves, and today they are available to Florida home gardeners at no charge. FDACS Division of Plant Industry provides vials of live Tamarixia radiata for release on your property, and UF/IFAS Extension county offices often host distribution and “access” events.

Two easy ways to request wasps

• Apply online through FDACS: FDACS Asian Citrus Psyllid Biological Control (Asian Citrus Psyllid Biological Control – Florida Department of Agriculture & Consumer Services).
• Contact your county Extension office: find your local UF/IFAS office. Solutions for Your Life – University of Florida, Institute of Food and Agricultural Sciences – UF/IFAS.

Releasing them in three steps (from FDACS instructions)

Your vials contain live wasps and a small strip of paper towel lightly coated with honey to keep them fed. Release them as soon as possible for best results; the sooner they’re in your tree, the better they survive. Then follow these steps:

1. Find the psyllids first. If possible, locate an infestation of Asian citrus psyllids on your citrus, or on orange/orange jasmine plantings. If you can’t identify an infestation, that’s OK, release within the citrus canopy anyway; the wasps will actively seek out psyllid nymphs on their own.
2. Uncap the vial in the canopy. Hold the vial near the canopy with the opening facing upward and place it securely in the tree so the wasps can leave on their own.
3. Return to release the rest. Come-back a little later to remove the vial, gently tapping out any remaining wasps into the tree.

See here how it looks like! 

Quick Check: Test Your Tamarixia Know-How

Question 1: You can’t find any psyllids on your tree. You should:

A) Skip the release and save the wasps
B) Release in the canopy anyway, the wasps will hunt
C) Spray insecticide first

Question 2: You received two vials. You should:

A) Empty both into one tree
B) Spread them among different trees or areas
C) Save one on the shelf for next month
(Answers: B, B)

Be Part of the Solution

Releasing Tamarixia on your property helps your citrus and your neighbors’ citrus, and it adds one more foothold for this beneficial wasp across Florida. It’s free, it’s easy, and it puts real UF/IFAS and FDACS science to work right in your own backyard. Reach out to your county Extension office to get started.

Let biology work ! Tamarixia is a marathon ally, not a one-shot fix.

Remember: You can’t spray your way out of greening — but a pinhead-sized wasp, released again and again, quietly tips the odds back in your favor.

Questions?

Does Tamarixia  cure citrus greening? No. It works by kills the Asian citrus psyllid; it does not cure the bacterial infection in an already-sick tree.
How big is Tamarixia radiata? About 1-millimeter length. Imagine the size of a pinhead… or see my Facebook video
Is it safe to release in my yard? Absolutely. It goes only to the Asian citrus psyllid and no other insects.
How many psyllids can one wasp kill? Depending on above discussed, about 500 in her lifetime, through parasitism and host feeding.
How do I get Tamarixia in Florida? Free from the FDACS Division of plant Industry… see below

Something else…Contact Your Local Extension Office

Every grove is unique. Reach out to your UF/IFAS Extension Agent or the biological control team that supplies the wasps at FDACS:

Amy Croft, Biological Scientist I/ Gloria Lotz, Biological Scientist III

FDACS Division of Plant Industry, 1911 SW 34th Street, Gainesville, FL 32608

Email: Amy.Croft@fdacs.gov     Phone: (352) 395-4738

Learn More & Sources

• EENY 475/IN858: An Asian Citrus Pysllid Parasitoid Tamarixia radiata (Waterston) (Insecta: Hymenoptera: Eulophidae)
• Citrus Psyllid Wasp – Gardening Solutions
• pdf
• Tamarixia radiata Waterston [Hymenoptera: Eulophidae],an ectoparasitoid of Diaphorina citri Kuwayama [Hemiptera: Psyllidae]Tamarixia radiata
• Asian Citrus Psyllid Tamarixia Parasitoid / Natural Enemies Gallery / UC Statewide IPM Program (UC IPM)

An Equal Opportunity Institution. UF/IFAS Extension, University of Florida, Institute of Food and Agricultural Sciences. This document is available in alternative formats upon request; contact your local UF/IFAS Extension office for accommodations.

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