Lace bugs are some of the most economically important Hemipterans. Lace bug damage from species in this genus can be severe on certain broad-leaved evergreen ornamental plants. Species that occur on these hosts overwinter as eggs either inserted in leaf veins or cemented to leaves with a brown material. In Virginia, eggs hatch in May. Typically, in geographic locations north of Virginia, egg hatch occurs before the end of May. Two generations may occur per year in northern geographic locations, and three per year in southern locations. The azalea lace bug (S. pyrioides) is native to Japan and a primary pest of azalea. It is known from MA to NY, FL, and many other US states. In Maryland, four generations of the azalea lace bug are known to occur per year. S. takeyai has a life cycle similar to that of the azalea lace bug. Eggs are deposited on the undersides of leaves and covered with a brownish substance that hardens into a protective covering. There are five nymphal stages (instars) and in Connecticut, four generations per year have been observed. S. takeyai was introduced into Connecticut from Japan in 1945. Since then it has been found from parts of North Carolina and northward to Maine. Adults are approximately 1/8 inch in length, flat, and with various colors or markings depending upon the species. Wings are lace-like in appearance on the adults. Nymphs may have spiky protrusions on their bodies, and lack wings.
While lace bug feeding occurs on the underside of the leaf, damage from the feeding can be seen on the upper leaf surface. The upper surface of the leaves appears chlorotic, while the undersides have brown or black varnish-like spots (tar spots) of excrement. From a distance, lace bug feeding may resemble spider mite injury to plants. Inspection of the leaf underside (to search for the tar spot-like excrement) can help confirm lace bugs as the cause of the damage. Cast (shed) skins from the nymphs may also remain attached to leaf undersides for some time. Feeding damage from lace bugs can be serious. Early season damage from this insect might mean that foliage remains unsightly and less functional for more than a year. Shrubs planted in sunny locations may suffer entire leaf yellowing/browning and dieback. On occasion, shrubs in sunny locations are killed.
Begin scouting for lace bug activity in May, particularly the end of May/beginning of June in Massachusetts. Look for signs of chlorotic/stippled leaf surfaces, and flip leaves over to observe the undersides to confirm lace bug presence. Scout plants that have a history of lace bug infestation. Continue scouting throughout the growing season, as lace bugs have multiple generations per year, including into the fall.
Avoid planting host plants in sunny locations, as this abiotic condition may favor lace bug populations. Reduce plant stress and water properly. A strong jet of water from a hose (syringing) may be targeted at the undersides of host plant leaves to dislodge adults and nymphs. Any remaining individuals may continue to feed on the plant. Certain azalea and andromeda cultivars vary in their susceptibility to lace bugs. Andromeda cultivars such as 'Temple Bells' and 'Cavatine' may be preferred by S. takeyai over 'Variegata' and 'Prelude' (Nair et al, 2012). Pieris floribunda and its hybrids may be less preferred when compared with P. japonica.
The azalea lace bug (Stephanitis pyrioides) has known natural enemies such as Anagrus takeyanus ( egg parasitoid) and Stethoconus japonicus (predator) (Invasive Species Compendium; CABI). The impact of natural enemies on lace bug populations is enhanced in shady landscapes with more structural complexity, particularly those with overstory trees and flowering plants (Shrewsbury and Raupp, 2000).
Abamectin (NL)
Acephate (NL)
Azadirachtin (NL)
Beauveria bassiana (NL)
Bifenthrin (NL)
Carbaryl (L)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Clothianidin (NL)
Cyfluthrin (NL)
Deltamethrin (L)
Dinotefuran (NL)
Fenpropathrin (NL)
Flonicamid+cyclaniliprole (N)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Imidacloprid (L)
Insecticidal soap (NL)
Lambda-cyhalothrin (L)
Malathion (L)
Permethrin (L)
Pyrethrin+sulfur (NL)
Spinetoram+sulfoxaflor (N)
Concentrate sprays (of contact insecticides) on leaf undersides. Management of the first (early) or second generation of lace bugs may prevent more extensive damage later in the season.
When used in nursery settings, chlorpyrifos is for quarantine use only.
Active ingredients that may be applied systemically include: Abamectin (injected), acephate (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), clothianidin (soil drench), cyantraniliprole (NL), dinotefuran (soil drench), and imidacloprid (soil drench).
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.