How to Manage Pests

Pests in Gardens and Landscapes

Lygus bugs—Lygus hesperus

Adult lygus bugs are green, straw yellow, or brown with a conspicuous yellow or pale green triangle on their backs. Nymphs are light green.

Identification

Lygus bug nymphs are light green and when tiny can be confused with aphids; however, they move much faster than aphids do and have red-tipped antennae.

Lygus bug damage to fruit may sometimes be confused with stink bug damage. Lygus bugs can cause discoloration, bumps, or depressions on fruit, but without the pithy or corky and discolored areas beneath that are characteristic of stink bug damage.

Life cycle

Lygus bugs overwinter as adults in plant debris, in crowns of plants, and in uncultivated areas adjacent to the garden. Their favored overwintering hosts are alfalfa, yellow starthistle, Russian thistle, wild radish, sweet clover, wild mustard, lupine, and vetch.

Adults mate in spring when the weather warms up and lay eggs on a wide range of broadleaf plants. Eggs are inserted into plant tissues flush with the tissue surface. They hatch in 1 to 4 weeks, depending on temperature, and there are five nymphal instars. The first four instars require 2 to 7 days each, and the fifth instar requires 4 to 10 days. Newly emerged females begin laying eggs in about 10 days. There are three to four overlapping generations each year.

Damage

Lygus can move into gardens or orchards from weeds, especially when they dry up. They are a particular problem in beans, strawberries, and orchard crops, feeding on developing flower buds and fruit. Fruit may become blemished and discolored, deformed, or twisted and may develop depressions or pustules.

Solutions

The best strategy for managing lygus is to remove sources of infestation before damage is likely to occur on the crop. Remove weeds adjacent to the garden before the crop is planted or before susceptible fruit or buds appear on trees. Insecticides are not usually necessary or effective in the garden. Insecticidal soaps sprayed directly on nymphs will kill them. Natural enemies attack lygus but do not usually control them.

Lygus bug adult
Lygus bug adult

Lygus bug nymphs
Lygus bug nymphs

Distorted strawberry
Distorted strawberry
Damage to pear
Damage to pear

Statewide IPM Program, Agriculture and Natural Resources, University of California
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