common name: blueberry gall midge
scientific name: Dasineura oxycoccana (Johnson) (Insecta: Diptera: Cecidomyiidae)
A gall midge, Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae), is a recently
discovered pest of rabbiteye blueberries (Vaccinium ashei Reade) in the southeastern US
(Lyrene and Payne 1992). Midge larvae feed inside and destroy flower buds resulting in low
yields. Midges also cause severe damage to vegetative growth. Plants cannot produce enough
foliage to support a heavy fruit crop, resulting in smaller berries with low sugar. Some
blueberry varieties have suffered a 100% crop loss due to depredations of this midge. The
problem is most pronounced in southern portions of the rabbiteye blueberry production range
where winter temperatures favor emergence of adult midges and larval development during
critical stages of blueberry flower development. South of Gainesville, Florida, commercial
rabbiteye blueberry production is not feasible if midges are left uncontrolled.
Dasineura oxycoccana is known from the northern United States (Maine, New Jersey,
Michigan, Wisconsin, Washington) where it infests vegetative buds of blueberry and
cranberry (Vaccinium macrocarpon Aiton). In southeastern Georgia, southern Mississippi,
and Florida, midge populations attack both flower and vegetative buds of blueberry. Florida
county records include (from north to south) Okaloosa, Washington, Alachua, Putnam,
Marion, Citrus, and Hillsborough counties.
Adults are tiny, fragile flies approximately 2 to 3 mm long. Mature larvae are about 1 mm long
and 0.3 mm wide, legless, and yellow to red in color. Gagné (1989) provides excellent details
on larval and adult gall midge morphology.
adult
larvae
The biology of the blueberry midge is still poorly known in the southeastern US. In North
Florida, midges apparently produce five or six generations between early January and early
June. The adult stage (during which mating and egg-laying take place) probably lasts only
from one to a few days. Eggs are oviposited between the scales of flower buds after the buds
begin to expand. Totally dormant buds are not infested. Eggs hatch in two to three days.
Since larvae digest plant tissues, they are the plant-damaging stage. There may be from one to
nine larvae in a single flower bud. Larvae apparently feed on bud tissues and on the pedicels
that hold the individual flower buds to the peduncle within the developing flower cluster.
Larvae probably drop to the ground after feeding, then pupate and transform to the adult stage.
Under laboratory conditions, infested flower buds yielded adults after 12 days. Flower buds
are subject to continuous oviposition from January to March. As plants progress to vegetative
budding, oviposition also occurs on the new shoot meristems. Infested vegetative buds swell
and the outer leaves curl enfolding feeding larvae inside. Oviposition continues until the end
of May. During summer, fall, and early winter in Florida, larvae apparently enter
developmental diapause and remain in the soil.
Flower buds dry up and disintegrate within about two weeks after infestation. High levels of
flower bud abortion may occur during winter and early spring. The severity of damage varies
from year to year and tends to be worse after mild winters and in more southern locations.
Vegetative meristems may also be infested and killed or damaged leaving only very short
shoots with a few highly distorted leaves. After mid-May, little damage occurs in Florida even
though new growth flushes continue throughout the summer. The severity of damage also
varies from field to field. Young plantings in their 2nd or 3rd year often flower and fruit well,
even while nearby fields of mature plantings have severe bud loss. This suggests a low
vagility (dispersion ability) of the midges and a slow population increase to pest proportions.
bloom damage
meristem damage
Rabbiteye blueberry cultivars vary greatly in their resistance to blueberry gall midge
infestation. 'Powderblue' and 'Brightwell' are highly resistant to flower bud damage;
'Climax', 'Aliceblue', 'Beckyblue', 'Bonita', 'Tifblue' and 'Woodard' are moderately
susceptible; and 'Premier' and 'Windy' are highly susceptible. Most southern highbush
blueberry (Vaccinium corymbosum L.) cultivars are highly resistant to flower bud damage.
Vegetative meristem resistance is not necessarily associated with flower bud resistance, and
there is wide variation in resistance among cultivars. Among rabbiteyes, 'Climax' is one of
the most susceptible to meristem damage, and plants may remain almost leafless until late
spring in years with high midge pressure. Despite their good flower bud resistance, highbush
cultivars do suffer considerable meristem loss, although most cultivars are still able to foliate
well.
Control methods are still under investigation (Lyrene and Payne 1995). Adults are readily
killed with insecticides. However, their multivoltine life history and short adult lifespan
necessitate careful scouting and timing of insecticide application. Contact your county
Cooperative Service Extension agent or office for latest applicable insecticides. Egg and
feeding larval stages are less easily killed, since these stages are at least partially protected by
surrounding plant tissue. Larvae and pupae in the soil may be susceptible to a soil drench
insecticide treatment. Any insecticide treatment during the blueberry flowering period must be
judiciously applied because insect pollinators are active at this time. Alternatively, insecticides
could be applied after flowering when vegetative meristems are under attack and huge midge
populations are developing. This timing would reduce the oversummering larva population
and subsequent midge attack the following winter and spring.
Cultural controls may be effective. Shallow disking beneath blueberries, probably in late fall
or early winter, may kill diapausing larvae in the soil or expose them to predators. Likewise,
using a disk to spread a thin layer of sand under the blueberry bushes may inhibit adults from
emerging from the buried pupae.
Insect Management Guide for blueberries
- Gagné RJ. 1989. The Plant-feeding Gall Midges of North America. Cornell University Press, Ithaca, NY. 356 pp.
- Lyrene PM, Payne JA. 1992. Blueberry gall midge; a pest on rabbiteye blueberry in Florida. Proceedings, Florida State Horticulture Society 105: 297-300.
- Lyrene PM, Payne JA. 1995. Blueberry gall midge: a new pest of rabbiteye blueberries. Journal of Small Fruit Production, in press.
Authors: G.J. Steck, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, P.M. Lyrene, University of Florida, and J.A. Payne, USDA.
Originally published as DPI Entomology Circular 373.
Photographs: Division of Plant Industry and USDA
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-136
Publication Date: June 2000
Copyright 2000 University of Florida
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Department of Entomology and Nematology
Division of Plant Industry
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