Bur oak and the macarena

Or is that Aceria mackei ? (Really, the current name for this mite is Eriophyes mackei.) Blister gall mites on bur oak were common near Bemidji during 1998. Aceria mackei mites attack spring foliage, causing large blister-like swellings on the upper surface of bur oak leaves. The blisters are similar in size and shape to injury by the oak leaf blister fungus, Taphrina cocrulescens. The blisters are oblong and up to ½ inch long, glossy green and, later, turn brown. On the underside a dense, greenish to yellow concave pocket forms which later turns brown. Leaves roll, curl, or become grossly distorted because of the loss of sap caused by large populations of mites.

Kermes scale on bur oak

Kermes scales were found in scattered parts of Beltrami and Hubbard County. The reddish brown female scale bodies are the only durable sign of infestation. They are spherical in shape, about 1/4 inch in diameter and are tightly attached to the twigs. Kermes scaleScales suck plant juice from the twigs and stems causing the twigs to dry up and wilt. Immature scales, called crawlers, are found feeding on the undersides of leaves and petiole where they suck plant juices from leaves giving leaves a bronzed dried out appearance. The main injury caused by scale insects is the ingestion of plant sap, resulting in loss of plant vigor, poor growth, die back of twigs and branches and leaf drop. Usually, natural enemies and fungal parasites regulate scale populations so chemical control is usually not warranted unless trees are experiencing impact at drought or have recently had root suffocation because of high water or some other adverse abiotic condition.