After feeding, they drop off the leaf and pupate in the soil. Midge large feed for about a week, during which time they can be observed on the underside of the gall (Figure 14). As they mature, they grow into a circular red blister surrounded by green surrounded by red that deepens into maroon (Figure 13). They begin as small yellow-green circles (Figure 12). ![]() x freemanii) DescriptionĮyespot galls form in the spring. pensylvanicum), mountain maple ( Acer spicatum), Freeman’s maple ( A. Scientific name: Acericecis ocellaris (Osten Sacken, 1862) Eyespot gall midge, occelate gall midge Classification Photograph by Sam Kieschnick via iNaturalist, used under a CC BY 4.0 license. Box elder leaves deformed by box elder pouch galls. Photograph by Woolcarderbee via iNaturalist, used under a CC BY-NC 4.0 license.įigure 11. Box elder pouch galls on the underside of a leaf, which appear as a fuzzy pubescence. Photograph by kimcwren via iNaturalist, used under a CC BY-NC 4.0 license.įigure 10. The galls appear as dimples on the upper leaf surface. Box elder pouch galls on a box elder leaf. Infestations that occur when leaves are growing can cause leaf deformities (Figure 11).įigure 9. Box elder pouch gall Classificationīox elder pouch galls look like an expanded pouch on the upper leaf surface (Figure 9) and an open dimple filled with white pubescence on the underside of the leaf (Figure 10). Photograph by Kelly Krechmer via iNaturalist, used under a CC BY-NC 4.0 license. Note the dry, crinkled appearance of the infested leaves compared to the healthy leaves in the background. Dying maple leaves with heavy erineum gall infestations. ![]() Photograph by Joe Walewski via iNaturalist, used under a CC BY-NC 4.0 license.įigure 8. In heavy infestations, individual erineum galls can merge into larger patches that sometimes cover an entire leaf. Photograph by Jason M Crockwell via iNaturalist, used under a CC BY-NC-ND 4.0 license.įigure 7. Like other gall mites, heavy infestations can impact the photosynthetic potential of individual leaves but don't generally impact overall tree health (Figures 7,8).įigure 6. The exact fall morphology varies somewhat between mite species and host trees, but in general the galls are green or red fuzzy patches resembling felt on the lower and upper leaf surfaces (Figure 6). saccharum), Norway maple ( Acer platanoides), mountain maple ( Acer spicatum) Description Scientific name: Aceria spp., Aculops spp. Erineum or felt gall mites Classification Photograph by karenandphillip via iNaturalist, used under a CC BY-NC 4.0 license. Notes the spiky appearance of the leaves. Maple leaves heavily infested with spindle galls. Photograph by Nick Furlan via iNaturalist, used under a CC BY 4.0 license.įigure 5. Photograph by Timothy Frey via iNaturalist, used under a CC BY 4.0 license.įigure 4. Otherwise, the life history is similar to that described for maple bladdergall mites above.įigure 3. In high abundance, they can give the leaf a spiked appearance (Figure 4). The galls are green but may turn pinkish. Maple spindle gall mites induce small, elongate, projecting galls on the upper surface of foliage (Figures 2, 3). Scientific name: Vasates aceriscrumena ((Riley & Vasey, 1870) ![]() Photograph by Michael Cooper via iNaturalist, used under a CC BY-NC 4.0 license. Heavy infestations of maple bladder galls can deform leaves and reduce a leaf's ability to photosynthesize. Photograph by epic2112 via iNaturalist, used under a CC BY-NC 4.0 license.įigure 2. Young mites hatch from the eggs and remain within the gall until they reach maturity, at which time they move to new leaves to start new galls.įigure 1. Mating and egg deposition also takes place within the gall. Galls have an opening on the underside of the leaf, so mites can exit the gall if necessary. Early in the spring they migrate to newly expanding leaves and begin to feed. Maple bladdergall mites overwinter as adults under bark scales and other protected sites on the host tree. In some cases, galls become so abundant that infested leaves become deformed (Figure 2). The galls are initially green, then turn red, and eventually black. These galls are usually noticed during May, about the time the leaves are fully expanded. Maple bladdergall mites induce globular growths about 2.5-3 mm in diameter on the upper leaf surface (Figure 1). Order: Trombidiformes (Trombidiform mites) Hosts Scientific name: Vasates quadripedes Shimer, 1869 While these galls may be aesthetically unappealing to some, they do not affect the overall health of the infested tree and rarely warrant control. Maple leaves are often host a variety of brilliantly colored, odd-shaped galls, which are caused eriophyid mites and gall midges. Galls are irregular plant growths that are induced by a range of different of insects and mites.
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