Citrus

Invertebrate Damage to Leaves

On this page
Sucking pests
  • Aphids
  • California red scale
  • Citrus red mite
  • Glassy-winged sharpshooter
  • Greenhouse thrips
  • Sooty mold
  • Twospotted spider mite
Chewing pests
  • Brown garden snail
  • Caterpillars
  • European earwig
  • Forktailed bush katydid
  • Grasshopper
  • Citrus leafminer
Exotic pests
  • Asian citrus psyllid
  • Brown citrus aphid
  • Diaprepes root weevil
  • Light brown apple moth

Sucking pest damage
Chewing pest damage
Mining damage

Names link to more information on identification and management.

Click on photos to enlarge

Sucking pest damage

California red scale
California red scale leaf spotting
Identification tip: Look for orange- to-brown round scale covers on blotchy discolored leaves. Purple scale also mottles leaves, but its covers are darker and elongate, resembling tiny mussel seashells. Mites, thrips, and diseases and disorders also discolor leaves.

Citrus red mite stippling
Citrus red mite stippling
Identification tip: Bleached or pale, speckled leaves are often caused by citrus red mite feeding. Twospotted spider mite, Texas citrus mite, Yuma spider mite, and (rarely) leafhoppers also stipple leaves. Discolored fruit or silk webbing may be present depending on the species of mite.

Twospotted spider mite leaf discoloring
Twospotted spider mite leaf discoloring
Identification tip: Pale yellow-to-brown dead patches can form in leaf tissue where twospotted mites feed. Sunburn and other diseases and disorders can cause similar foliage injury.

Greenhouse thrips bleaching and excrement
Greenhouse thrips bleaching and excrement
Identification tip: Greenhouse thrips foul plants with dark specs of excrement. Thrips and several mite species discolor, bleach, or stipple leaves or fruit. But unlike mites, thrips do not produce silk webbing.

Honeydew-producer excretions
Sooty mold
Identification tip: Where dark sooty mold or sticky honeydew is evident, look for phloem-sucking Homoptera, including aphids, cottony cushion scale, citricola scale, brown soft scale, black scale, mealybugs (shown here), and whiteflies. Also look for ants that tend these pests.

Glassy-winged sharpshooter excrement
Glassy-winged sharpshooter excrement
Identification tip: This whitish, coating is sharpshooter excrement. Infested leaves may also have elongate yellowish blisters or brown scars where females inserted their eggs.

Aphid leaf distortion
Aphids' leaf distortion
Identification tip: Curled leaves and shoots are usually harmless if infested by aphids. But look closely to determine the actual cause as foliage can be distorted by Homoptera, caterpillars that web foliage, citrus thrips, citrus leafminer, citrus bud mite (in coastal lemon), and certain diseases and disorders. Be alert for the introduction of new pests such as the exotic brown citrus aphid, which is very efficient at vectoring citrus Tristeza virus, greatly increasing the severity of this disease. Report suspected new pests to agricultural officials.

Asian citrus psyllid
Asian citrus psyllid (PDF) wax debris
Identification tip: This exotic, aphidlike insect sucks phloem, distorting leaves and shoots. The yellowish orange nymphs produce abundant white wax. The brownish adults spread citrus greening disease (Huanglongbing), caused by a citrus tree-killing bacterium. Report to agricultural officials any findings of this pest.

Brown citrus aphid
Brown citrus aphid honeydew
Identification tip: Shiny honeydew on leaves is caused by aphids and other phloem-sucking pests. Be alert for the introduction of new pests such as the exotic brown citrus aphid, which is very efficient at vectoring citrus Tristeza virus, greatly increasing the severity of this disease. Report suspected new pests to agricultural officials.

Chewing pest damage—Top of page

Forktailed bush katydid chewing
Forktailed bush katydid chewing
Identification tip: Leaf chewing, either along the edges or in the middle of leaves, may be caused by katydids. If katydids are the cause during spring, the amount of leaf damage is relatively low. But if young fruit are present, look for a circular scar near the center of fruit, which is the economic damage katydids cause. Earwigs, citrus cutworm, and other species of caterpillars cause similar damage.

Grasshopper chewing
Grasshopper chewing
Identification tip: Grasshoppers chew foliage, usually from the leaf edges. Some leaves can be so extensively chewed that only the main vein remains. Young trees can be severely defoliated if grasshoppers are abundant. Damage is most likely on trees growing near unmanaged vegetation, from which grasshoppers migrate to citrus.

European earwig chewing
European earwig chewing
Identification tip: Earwigs chew buds, leaves, or small fruit. Chewing damage can be common on trees with trunk wrappers, on lower canopy foliage where trees are not skirt-pruned, and where abundant leaf litter or other harborage provide earwigs places to hide during the day.

Caterpillar chewing
Caterpillar chewing
Identification tip: Chewed or ragged leaves, scraped or pitted fruit and foliage, and silk webbing on plants are caused by amorbia, citrus cutworm, omnivorous looper, orange tortrix, and (less often) by larvae of other moths. If chewed leaves are near fruit, fruit are also often chewed. Only caterpillars both chew plants and produce silk webbing.

Weevil chewing
Diaprepes root weevil chewing
Identification tip: Ragged, notched, or serrated leaf margins, usually on lower or interior foliage, can be from Fuller rose weevil or the exotic Diaprepes root weevil (244 KB, PDF); in comparison Diaprepes root weevil chews notches that are larger and tend to occur more widely throughout the tree. Unlike Fuller rose beetle, Diaprepes rolls or glues leaves together where it lays its eggs. Report to agricultural officials any findings of the exotic Diaprepes root weevil.

Brown garden snail chewing
Brown garden snail chewing
Identification tip: Snails chew irregular holes in leaves and fruit and produce shiny, dry or wet, slimy trails on plants and the ground. Snails feed mostly at night. If they are the suspected cause of chewing, look for snails where they rest during the day beneath trunk wraps, in leaf litter, around irrigation emitters, or attached to leaves or bark.

Caterpillar leaf shelter
Light brown apple moth larva shelter
Identification tip:  Young citrus leaves and shoots are chewed, rolled, and webbed by several leafroller species (Tortricidae), including amorbia, fruittree leafroller, and orange tortrix. Light brown apple moth, an exotic pest, also causes this damage. Pheromone-baited traps are a primary way to distinguish which species of moth is present. Report to agricultural officials any findings of this exotic pest.

 

 

Mining damage—Top of page
Citrus leafminer mine
Citrus leafminer mine
Identification tip:  Citrus leafminer bores pale or dark (excrement-filled) winding tunnels just under the leaf surface. Infested succulent shoots and young leaves may be distorted, galled, or rolled.
 

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