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Erythrina Gall Wasp

The Erythrina Gall Wasp is an exotic pest of the Wiliwili tree (Erythrina variegata).  Common tree names include tigers claw, Indian coral tree and Wiliwili-haole.  It was first discovered in Hawaii in 2005.  Populations of Wili-Wili or Erythrina occur in Hawaii, California and Florida.  EGW completes its lifecycle in as little as 21 days.  It is a destructive, exotic pest that may kill trees in as little as two years. If trees are at risk of EGW infestation, inspect trees on a regular basis, especially the new foliage.  Look for swelling (galls) in leaf tissue and in twigs.  It is our recommendation to treat to protect trees in advance of an infestation or as soon as possible following EGW detection.

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Erythrina Gall Wasp is an exotic leaf and twig galling wasp that attacks Wili-Wili trees. The developing EGW larvae induces galls in tender leaf and stem tissue. Unchecked infestations cause leaf deformation, reduction in growth, defoliation and tree death.


Photo A taken by M. Tremblay
Photo B taken by Albert Mayfield, Florida Department of Agriculture and Consumer Services, Bugwood.org
Photo C taken by M. Tremblay
Photo D taken by Albert Mayfield, Florida Department of Agriculture and Consumer Services, Bugwood.org

Research studies were conducted independently in Hawaii by the University of Hawaii and the USFS to evaluate the efficacy of Arborjet's IMA-jet (5 % imidacloprid) systemic insecticide for treatment of Erythrina Gall Wasp. Trees that were systemically treated with IMA-jet effectively controlled EGW in both the ornamental landscape and in native, dry upland sites.

IMA-jet is a systemic insecticide used to control a variety of insect pests of ornamental or forest trees. Pests controlled include aphids, whiteflies, soft scales, adelgids, gall forming wasps, leafhoppers, lace bugs, mealybugs, psyllids, serpentine leafminers, sawflies, thrips and leaf feeding beetles. Use IMA-jet as directed in trees in residential, business and commercial areas, golf courses, airports, cemeteries, parks, street trees, playgrounds, athletic fields, commercial forestry production, seed orchard trees, nurseries, and in private, municipal, state, federal, county and local recreational forests.

Read the entire label before use. Failure to follow label directions may result in poor control or plant injury.

Treat trees by microinjection (using the Arborjet QUIK-jet or Arborjet Air Hydraulic Device) or by Micro-InfusionTM (using the Arborjet TREE I.V.).

Dosages are based on the Diameter (in inches) of the tree at Breast Height (DBH"). Measure the tree diameter in inches at chest height (54"from ground) to find the Diameter at Breast Height (DBH). If measuring tree circumference, divide circumference by 3 to obtain the DBH in inches. Placement of Injection Sites: Make applications around the base of the tree. Inject into tree roots exposing them by careful excavation or, alternatively into the trunk flare or tissue immediately above the trunk flare, locating the injection site in the first few xylem (i.e., sapwood) elements. Make applications into intact, healthy sapwood. Do not inject into injured areas or areas with decay. Select injection sites associated with stem growth. Number of Injection Sites: Work around the tree, spacing injection sites approximately every 6.0 inches of tree's circumference. Drill Depth: Drill holes through the bark and into the sapwood a minimum of 3/8" deep. When using the Arborjet Arborplug, drill a minimum of 5/8" deep into the sapwood. Use clean, sharp drill bits. Brad point bits are recommended.

For optimum results, apply IMA-jet prior to infestation. Also apply when insects are infesting and feeding upon the tree. IMA-jet insecticide moves upward into the tree's canopy from the application sites. Systemic activity occurs only after the active ingredient is translocated upward in the tree. This product must be applied below the bark into the sapwood (i.e., the vascular) tissues.
Uptake is dependent upon the tree's transpiration. Transpiration is dependent on a number of abiotic and biotic factors, such as soil moisture, soil and ambient temperature, and time of day. For uptake, apply when soil is moist, soil temperatures are above 45 degrees F, ambient temperatures are between 40 degrees to 90 degrees F, and during the 24 hour period when transpiration is greatest, typically before 2:00 PM. Applications to drought or heat stressed trees may result in injury to tree tissue, poor treatment and subsequent control. Avoid treating trees that are moisture stressed or suffering from herbicide damage.

Dosages are designed for insect control and retreatment is generally not necessary during the year after initial treatment. Monitor insect activity to establish a damage threshold for retreatment. Repeat applications as necessary. Studies have demonstrated that label use rates of IMA-jet provided at least 13 months of control of EGW. Reduction of leaf and twigs galled were observed following systemic tree injection treatment. Treating with IMA-jet does not remove the existing galls (symptoms), but the active ingredient moves into the soft tissues where larvae feed to affect control.

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