The new growth on your lemon tree has gone wrong. The young leaves at the tips are twisted, curling in on themselves, and they never flattened out the way the older ones did. You look closer and there are tiny things on the undersides, about the size of aphids, brownish wings, and they scatter when you brush the leaf.
One detail separates this from every other bug you'll find on citrus here, and it's worth learning because it takes two seconds to check.
It stands on its head
The Asian citrus psyllid feeds with its head down against the leaf and its back end lifted into the air at close to a 45-degree angle. UC's pest note puts it plainly, no other insect pest of citrus positions its body that way. Aphids sit flat. Whiteflies sit flat. This one looks like it's doing a push-up.
The adult is small, about an eighth of an inch, with a pointed front end and red eyes. The nymphs are easier still, because they produce a waxy tubule out the back end that curls into a tube with a little bulb on the end, and nothing else on citrus makes that. If you find the curly wax, you've found this insect and you don't need anybody to confirm it.
The feeding damage itself is the twisting and curling you noticed. Leaves that got hit while they were still expanding carry a notch at the edge afterwards, so you can read the history on the older growth. The saliva is toxic enough to kill a new shoot outright.
The damage isn't why anyone cares
Here's the part that catches people out. On an established backyard orange or grapefruit, the psyllid's own feeding is a cosmetic problem. A mature tree shrugs off a season of twisted tips. If this insect only ate leaves, nobody would have a hotline for it.
It carries huanglongbing. HLB is a bacterial disease of citrus with no cure, and an infected tree gets removed rather than treated. That's the whole reason an insect the size of an aphid has a state program behind it.
Where this actually stands in our valley
The honest version matters more than the alarming one, so here it is in order.
The psyllid is here and has been for years. CDFA trapped it in Coachella and Mecca back in 2012, and all of Riverside and San Bernardino counties now sit inside the psyllid quarantine. Nobody is going to eradicate it from the Coachella Valley at this point, and no sensible plan assumes otherwise.
The disease is not here. The HLB finds inside Riverside County are all on the other side of the pass, in Corona, Jurupa Valley, the city of Riverside, and most recently Murrieta on 11 September 2026. Different climate, 60 miles of mountains in between. The closest detection to us came in from the opposite direction, when CDFA confirmed HLB in a single residential tree in Calexico on 21 August 2026, the first ever in Imperial County, down at the border on the far side of the Salton Sea.
So what we have in Indio, La Quinta and Thermal is the carrier without the cargo. That's a good position to be in and it's worth not wrecking.
The symptom that tells disease from desert soil
Everybody in this valley has seen a yellow citrus leaf. Our soil is alkaline and it locks up iron and zinc, so chlorosis is ordinary here, and if yellow leaves meant HLB then half the trees from Palm Springs to Mecca would be condemned.
The difference is symmetry.
A nutrient problem is even. The yellowing shows up between the veins on both sides of the midrib, matching left to right, usually across a whole flush of leaves at once. HLB is lopsided. UC describes it as an asymmetrical blotchy mottle, green patches on one side of the leaf and yellow on the other, with the pattern ignoring the midrib entirely. Fold the leaf along the center and a nutrient problem roughly mirrors itself while HLB doesn't.
The fruit tells the same story. HLB fruit comes out small and lopsided, stays partly green when it should have colored, carries dark shriveled seeds and drops early. A grapefruit that's still green at the blossom end in February on an otherwise reasonable tree is worth a phone call.
What it probably is instead
Most citrus calls we take in Rancho Mirage and Palm Desert turn out to be something ordinary, and the ordinary things look alarming too.
Silver scribbles winding across new leaves are citrus leafminer, and on an established tree the right response is to leave it be. Sticky leaves with a cloud of small white insects underneath is whitefly, and the sooty black film that follows is growing on their honeydew rather than attacking the tree. Plain aphids curl new growth as well, which is exactly why the 45-degree posture is worth checking before anyone panics.
The one thing that matters more than spraying
UC's guidance on treatment is narrow, only apply pesticides if the psyllid has actually been found on your trees. There's no case for spraying citrus on a schedule out here against an insect nobody has confirmed is on the tree.
The rule that actually protects this valley is the boring one. Don't move citrus plants or clippings. Not a cutting from a relative's tree in Corona, not a potted lemon off the back of somebody's truck, not a bag of leaves from a trip over the hill. Every jump HLB has made into a new California county started as plant material somebody carried. Buy citrus from a licensed local nursery and the paperwork does this work for you.
If you think you've found psyllids or you're looking at a lopsided mottled leaf, CDFA's pest hotline is 1-800-491-1899 and the call is free.
What we do with a citrus call
We look at the insect if there is one, and then we look past it. Checking a leaf pattern for symmetry, reading the notches on last season's growth, looking at the irrigation and at how deep the water is actually going, and asking what's been planted nearby and when. Working a diagnosis means finding the first cause rather than the loudest symptom, and on citrus here the first cause is usually soil chemistry or water rather than anything with legs.
We'll also tell you when the answer is nothing. A tree carrying some leafminer, a bit of chlorosis and an ordinary psyllid population is a tree that needs its irrigation looked at, not a treatment plan.
When to call
Call at a normal pace if new growth is twisting on your citrus, if you've found insects sitting at that angle, or if yellowing has you unsure whether you're looking at soil or disease.
Call sooner if the mottling on a leaf is clearly lopsided across the midrib, if fruit is coming out small and staying green at the blossom end, or if a tree went downhill fast after new citrus arrived in the neighborhood.
We're on Highway 111 in La Quinta and we cover the valley from Palm Springs and Cathedral City through Indio and Coachella. If you want somebody to look at a citrus tree and tell you which of these you've got, that's a straightforward tree doctor visit from the Coachella Valley office.