The sharpnosed leafhopper, Scaphytopius magdalensis (Provancher), is a common pest of blueberries throughout the eastern United States. Adults are small brown insects, about 5 mm long (3/16 inch) with tiny cream-colored patches on the body and wings. Nymphs are ivory in color, and develop an hourglass pattern of brown or red markings on the dorsal surface as they grow. Sharpnosed leafhoppers are aptly named because both nymphs and adults have a pointed head that is shaped like the horn of an anvil.
- Adult stage of the sharpnosed leafhopper.
- First instar nymph.
- Fifth instar nymphs.
- Oviposition sites in a blueberry leaf.
- Yellow sticky traps used for monitoring leafhopper populations.
Symptoms and Damage
Feeding by sharpnosed leafhoppers causes very little direct injury to blueberry plants, but these insects are still considered major pests because they are able to transmit a mycoplasma-like pathogen that causes blueberry stunt disease (Tomlinson et al. 1950). Leafhoppers pick up the pathogen by feeding on infected plants and then carry the disease to other plants in subsequent feedings.
Life Cycle and Seasonal Distribution
In the southern part of its range, the sharpnosed leafhopper completes three generations per year. Overwintering eggs hatch about the time blueberry leaf buds begin to open, and nymphs complete development (five molts) in four to six weeks. Second generation adults are abundant in mid-summer, and third generation adults remain active in late fall until the first killing frost. High populations of sharpnosed leafhoppers develop in abandoned blueberry fields and in wooded habitats where huckleberry (Gaylussacia spp.) and blueberry (Vaccinium spp.) are common in the ground cover (Meyer 1984). Adults are able to fly long distances (probably carried on air currents), and they tend to disperse out of the woods during the spring (first) generation, and back into the woods during the fall (third) generation. The stunt pathogen is probably carried back and forth between commercial fields and wild reservoirs by this annual cycle of leafhopper dispersal.
Two parasites, a dryinid wasp and a bigheaded fly (family Pipunculidae) are often associated with sharpnosed leafhoppers in abandoned fields. Neither of these parasites are common in commercial fields, but in some cases, predation by spiders may have a significant effect on leafhopper populations (Hutchinson 1955).
Scouting, Management, and Control
Yellow sticky traps, like those used to catch adult blueberry maggots, seem to be the best way to monitor sharpnosed leafhopper populations. Traps should be hung directly on the bushes, in a clear spot, about 0.5 m (20 inches) above the ground. Counts of the trap catch should be made at least once a week throughout the growing season. Most of the individuals collected on yellow sticky traps are adults, and males usually outnumber females by 5 to 1. Both adults and nymphs can be collected from blueberry plants with a sweep net; this technique gives a better estimate of the sex ratio and population structure, but it tends to yield highly variable estimates of population density. Best results are usually obtained late in the day (near sunset) using a single upward sweep along the side of each bush in the row (Meyer and Colvin 1985).
Sharpnosed leafhoppers are quite susceptible to most of the insecticides registered for use on blueberries. In order to limit the spread of blueberry stunt, southern blueberry producers should time insecticide applications to coincide with the dispersal phase of each leafhopper generation. Spray should also be directed into the woods around the perimeter of each field to minimize re-infestation by migrant adults. To prevent the spread of stunt within a field, infected bushes must be promptly removed as soon as they begin to show symptoms of disease.
- Hutchinson, M. T. 1955. An ecological study of the leafhopper vectors of blueberry-stunt. J. Econ. Entomol. 48: 1-8.
- Meyer, J. R. 1984. Life history of the sharpnosed leafhopper [Scaphytopius magdalensis (Provancher)] and four related species in southeastern North Carolina. J. Georgia Entomol. Soc. 19: 72-87.
- Meyer, J. R., and S. A. Colvin. 1985. Diel periodicity and trap bias in sticky trap sampling of sharpnosed leafhopper populations. J. Entomol. Sci. 20: 237-243.
- Tomlinson, W. E., P. E. Marucci, and C. A. Doehlert. 1950. Leafhopper
transmission of blueberry stunt disease. J. Econ. Entomol. 43: 658-662.
Last updated: 28 June 1996
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