As you may be aware, the decline of citrus production in Florida negatively affects rural communities in our area the hardest. Our culture as a community lies on the continued cultivation of citrus. By this time, we would wake up to the sweet smell of orange blossoms, signaling that spring was fast approaching. Today many of us sure miss that smell.

The decline of this precious commodity rests on the back (or the mouthparts) of a tiny insect: the Asian citrus psyllid (Diaphorina citri Kuwayama).

The Asian citrus psyllid is not a new pest, but it is a small, mighty, and a terror! The psyllid has been in Florida since 1998, and it has since spread throughout Florida and outside the boundary of Florida.  It is important to understand the Asian citrus psyllid and its life cycle to manage its population to have a sustainable citrus crop. This psyllid is the culprit behind citrus greening, a debilitating disease to most citrus cultivars.

What is Hemiptera?

The Asian citrus psyllid is an insect in the Hemiptera superorder of insects,  which is commonly called the true bug family. It is called true bug because many people refer to any insect as a “bug” even if it is a spider.  True bugs have piercing-sucking mouth parts. The rostrum cuts the top layer of a leaf or flower allowing the bug to feed on the plant’s sap. The Asian citrus psyllid not only stabs the newly flush of leaves and sucks out the liquid contents, but it also potentially exchanges pathogens in the process.  Above all, this is how the bacterium that causes citrus greening disease (also known as Huanglongbing or HLB), Candidatus Liberibacter asiaticus is spread. For all the reasons we now see in our groves, the prevention of this disease, and the management of its vector the psyllid have astronomical economic importance to our region.   More on that later but check out this for a map on quarantine areas due to citrus greening. Quarantine areas

The Asian citrus psyllid’s life cycle

Since the psyllid is a true bug, it goes through complete metamorphosis. That means the young nymphs look completely different than the adult stage.  Here is a picture from David Hall, USDA, depicting the life stages.  It is important, when scouting for pests in your citrus trees, to look for the eggs.  The eggs are small but their golden yellow or orange color gives them away on the green leaf background.  One can look for the eggs using the description “pinched on one end and rounded on the opposing end.”  Coincidentally, the eggs can be found on any location of the new leaves, the petiole (the leaf’s base), and even on the stem near the leaf base.

The young nymphs go through several stages (5) feeding heavily and they leave behind a stringy, waxy white excrement as feeding evidence. Their beady red eyes do not mean they are mad at you, just an interesting characteristic of this psyllid. Depending on environmental conditions and the time of the year, it can take two weeks to go through the nymph cycle.  This is a short window for treatment if you are using pesticides for the nymphal stage.

The adult has a characteristic unusual stance that makes identifying it easy:  The adult appears to be doing pushups for exercise with their head tilted 30-45 degrees towards the leaf and abdomen sticking outwards away from the plant tissue it is perched on. This is the longest life cycle stage. They will remain an adult for up to 50 days.  Coincidentally, the female psyllid can have 30 overlapping generations per year laying about 800 eggs in her lifetime.  Cool facts and More facts on the life cycle.

Managing this tiny terror

Reading the label is very important and it’s the law.  Some of the pesticides labelled for psyllids are specific to their life cycle.  Some control the nymphs but do not control the adults.  Ovicides control the egg stage. The other pesticides for nymphs and adults usually don’t control the egg stage.  If you need a list of pesticides to rotate to effectively treat the psyllids, please check out this publication. Chart of Insecticides & Miticides

If you want to use biological control for the Asian citrus psyllid before chemical treatment, there are two prominent parasitic insects (wasps) ready for battle. Don’t worry, they won’t sting you, just the psyllid! In 2019, USDA had a biological release program for homeowners to combat the psyllids. Although it is not available today, the parasitic insects can be purchased via the internet.  Tamarixia radiata lays eggs on the nymphal stage reducing the number of reproducing adults. More details on this parasitoid. Parasitoid facts

Diaphorencyrtus aligarhensis is the other wasp that is parasitic to the nymphal stage.  There are other psyllid biological insects that you may already be familiar with, the ladybugs, lacewings, syrphid fly larvae, and spiders.  Chemical control, specifically insecticides, should not be used with biological control since the biologicals are mostly insects too.

This is the first article in a series of articles on citrus, its management, and pest pressures.

If you need further information on strategies to manage citrus pests or production, please give us a call or come by the UF/IFAS Extension Office in Hardee or Desoto County. If you have any questions related to this article, please contact Lisa Hickey via email at lisa.hickey@ufl.edu or Jona Bosques at jonael@ufl.edu. The Hardee County Extension Office is located at 507 Civic Center Drive, Wauchula FL 33873 or 863-773-2164. The Desoto County Extension Office is located at 2150 NE Roan St, Arcadia, FL 34266 or (863) 993-4846.
Resources:

2024–2025 Florida Citrus Production Guide: Huanglongbing (Citrus Greening). M. M. Dewdney, T. Vashisth, and L. M. Diepenbrock. Guide to manage citrus greening

2024-2025 Quick Reference Guide to Citrus Insecticides and Miticides. L.M. Diepenbrock, L. L. Stelinski, J. D. Burrow, and J. A. Qureshi. Insecticides & Miticides

Asian Citrus Psyllid and Citrus Greening. Citrus Greening from Asian citrus psyllid

Asian Citrus Psyllid, Diaphorina citri Kuwayama (Insecta: Hemiptera: Psyllidae). F. W. Mead and T. R. Fasulo. Asian citrus psyllid

Citrus Pest Quick Guide: Asian Citrus Psyllid. L. M. Diepenbrock and J.D. Burrow. Psyllid Quick Facts

FDACS Quarantine Map. FDACS quarantine map

Featured Creatures, Asian citrus psyllid. Asian citrus psyllid creature

Featured Creatures, Asian citrus psyllid parasitoid. Beneficial parasitoid wasp

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