Potato Psyllid, Bactericera cockerelli 

Potato psyllid is the most damaging insect to potatoes and tomatoes in Colorado.

Order: Hemiptera
Family: Triozidae


The adult potato psyllids somewhat resemble a miniature cicada, but are about the size of a large aphid. They are dark gray and have a couple of prominent vertical white bands on the abdomen and horizontal stripes on the thorax. When disturbed, the adult can jump. Females lay eggs on the leaves, usually at the margins. The eggs are barely visible, orange-yellow and supported by small stalks. Nymphs emerge within about a week after eggs are laid, then settle on the leaf and begin to feed. Newly hatched nymphs are flattened, broadly oval and lack wings. They are dull yellow or orange and become progressively greener as they feed and develop. During the growing season, four or more generations can be produced. Potato psyllids do not survive outdoors in areas with cold winters, such as Colorado. Infestations each year result from migrations from southern areas such as Texas and Northern Mexico where psyllids overwinter on nightshade family plants (potato, tomato, peppers, and multiple weeds).  

psyllid nymphs

Whitney Cranshaw, Colorado State University, Bugwood.org. 
Various stages of psyllid nymphs.

sugar excrement on tomato plant

Whitney Cranshaw, Colorado State University, Bugwood.org
Characteristic of sugar excrement on tomato plant.

Adult potato psyllid

Whitney Cranshaw, Colorado State University, Bugwood.org
Adult potato psyllid on a pepper leaf. 

Leaf symptoms

Whitney Cranshaw, Colorado State University, Bugwood.org
Leaf symptoms of psyllid yellows.

Quick Facts

  • Potato psyllid is the most damaging insect to potatoes and tomatoes in Colorado 
  • Injury is caused by toxic saliva introduced when the insect feeds. This can produce a serious disease known as “psyllid yellows” 
  • Psyllids can also transmit a bacterial pathogen which causes zebra chip disease  
  • Potato psyllid does not survive outdoors in Colorado through winter. New infestations occur annually from migrations that originate in Texas and northern Mexico 
  • Early detection and treatment of potato psyllid is important to prevent damage 


Plant Injuries caused by Potato Psyllid 

  • Psyllids feed on plant phloem, which is rich in sugars – excess carbohydrates are excreted in distinctive wax-covered pellets 
  • Nymphs move very little and can be difficult to see, so signs of their activity such as shed skins and excreted sugary pellets can be used to detect their infestations 
  • Psyllid saliva has toxic properties and can cause psyllid yellows – symptoms of this include yellowing of edges of foliage or entire leaves. This is associated particularly with nymphs.    
  • In potatoes, psyllid yellows symptoms include leaves that range from yellow to yellow-green (on white and russets potato varieties) to pale pinks and purples (in red and blue varieties). Areas of the stem will swell, and sometimes small tubers will form above ground. Tuber size and yield may be significantly reduced by psyllid yellows.  
  • On tomatoes, psyllid yellows symptoms include slight pink/purpling of the new growth. Fruit may be smaller in size and skin color may be duller. Plant growth is retarded, and new growth may be smaller and sometimes slightly curled.  
  • Potato psyllid can vector the bacterium, Candidatus Liberibacter solanacearum (Lso), which causes zebra chip disease. Adult psyllids are more effective at transmission than nymphs. The disease affects the quality of the tubers and can render chipping potatoes unmarketable. Frying tubers affected by zebra chip produce distinct dark bands. 
  • Zebra chip incidence is generally low, although in some years the percentage of infected plants can reach levels resulting in significant losses to potato producers.  
  • Several other nightshade family plants can be infested by potato psyllid, including eggplant, tomatillo, and peppers. No significant effects on yield or quality on these crops have been observed in Colorado, although damage to peppers is reported in California 




  • Potato psyllid outbreaks occur irregularly and are unpredictable, so it is important to survey for this insect every year to identify potential for problems. 
  • In larger plantings, the use of a sweep net and yellow sticky traps are the best way to detect if adult psyllids are present. 
  • Detection of nymphs on leaves can confirm the presence of established and increasing psyllid numbers. Nymphs will be found on the underside of leaves, particularly on the lower half of the plant. Often a hand lens is required to see nymphs and eggs. 
  • The highly distinctive psyllid sugar excrement can also be a very useful diagnostic tool 




There are natural insect enemies of potato psyllid. Most important are predatory bugs, including damsel bugs and minute pirate bugs. Lady beetles and larvae of green lacewing will also feed on psyllids. In greenhouse production, fungi that infect potato psyllid may be used as a biocontrol. There are commercially produced formulations available, including Isaria fumosorosea and Beauveria bassiana. High humidity is important for effective suppression of the psyllids using these fungal biocontrol agents. Insecticide options for control of potato psyllid are very limited, and potato psyllids are resistant to a number of insecticides. 

CSU Extension Fact Sheet

Download or view the CSU Extension’s PDF fact sheet for your reference.