Round Bugs That Eat Tomato Plants


The tomato is perhaps the most widely grown plant in home gardens across the U.S., according to University of Illinois Extension. The fruit is eaten raw, cooked or baked, or pureed into paste. Although this sun-loving plant is generally easy to care for; it is susceptible to damage by a variety of insects including worms and two round bugs.


Psyllids (Bactericera cockerelli) and the Colorado potato beetle are names of the two round bugs drawn to the tomato plant.


Psyllids, the most common bugs that damages tomato plant, are often called "jumping plant lice" because their ability to hop and jump, reaching adjacent plants or different parts of the same plant easily, according to Colorado State University Extension. An adult bug measures 0.12 inches with a yellow or white marking on its thorax and wings. Its life cycle is comprised of three stages--the egg, nymph an adult. The tiny eggs measure 1/32-inch in length, and the round or slightly elliptical nymphs start yellow but eventually turn green. The Colorado potato beetle is commonly found on the leaves of the tomato plant where it feeds. The legs give its slightly oval body a more rounded look. It measures 1/2 inch long and 3/8 inches wide and features alternating rows of black and white strips on its back. Each female lays 500 eggs in a lifetime, usually under the leaves, and these are light to deep orange.


Nymph and adult psyllids feed on the juice of a tomato plant, causing those parts turn yellow. Damage by feeding nymphs is more severe as they inject a toxin that causes leaves of preflowering plants to curl; transplants to immediately die and larger plants to either produce excess fruit or none at all. According to the University of California Pest Management Program, these symptoms are collectively called "psyllid yellows". Colorado potato beetle adults and larvae feed on leaves of the host plant causing large holes or severed leaves. Although larval stage lasts two to three weeks, the beetles at this stage feed in groups, and cause severe damage or even death in extreme cases.

Chemical Control

Psyllids are so small that their presence is unnoticed by the naked eye until they begin damaging the tomato plant. Commercial insecticides containing esfenvalerate and permethrin are effective in controlling these bugs. Regular dusting of sulfur also controls small infestations. Although erratic, insecticidal soaps also control psyllids to some degree. Spray insecticides containing chloronicotinyl, abamectin, carbamate and chlorinated hydrocarbon to control Colorado potato beetle.


Pests develop resistance to repeated uses of the same insecticide. For effective control, alternate insecticides if using it as the only means of control. Also, spray insecticide thoroughly over the surface of leaves, including the often-missed areas under the leaves where the bugs hide.

Keywords: tomato plant bugs, round tomato bugs, tomato plant insects

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