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The common spangle gall on the underside of leaves and the currant gall on the male catkins or occasionally the leaves, develop as chemically induced distortions on pedunculate oak (Quercus robur), or sessile oak (Quercus petraea) trees, caused by the cynipid wasp [1] Neuroterus quercusbaccarum which has both agamic and bisexual generations.
Cockchafer feeds on deciduous plant and fruit tree leaves, including oaks, maple, sweet chestnut, beech, plum, and walnut trees. The feeding behaviour of larvae can cause severe damage to the plants. They feed on both the small roots of field plants such as grain, grass, tree, beet roots and the large part of crop rootlets.
The larvae feed on the leaves of oak trees in the eastern United States and southeastern Canada and are a major defoliator of oak trees, which can lead to tree mortality. In Pennsylvania in the late 1960s and early 1970s, oak leafrollers defoliated over 1,045,000 acres (423,000 ha).
Agrilus biguttatus prefers to reside in old oak trees of 30-40 cm in diameter [6] with an inner bark thickness of 10-13 mm. [9] While healthy trees can generally resist A. biguttatus infestations, female beetles tend to live in trees that are physiologically stressed, often as a result of drought conditions.
Cystotheca lanestris, the live oak witch's broom fungus, is a species of mildew that infects buds and induces stem galls called witch's brooms on oak trees in California, Arizona, and Mexico in North America. [2] [3] Witch's brooms are "abnormal clusters of shoots that are thickened, elongated, and highly branched."
Galls (upper left and right) formed on acorns on the branch of a pedunculate (or English) oak tree by the parthenogenetic generation Andricus quercuscalicis.. The large 2 cm gall growth appears as a mass of green to yellowish-green, ridged, and at first sticky plant tissue on the bud of the oak, that breaks out as the gall between the cup and the acorn.
But homeowners should be paying closer attention to their oak trees. Robert Spartz, district manager for the Davey Tree Expert Company in Eldridge, spoke with Our Quad Cities News via Zoom to ...
The larvae feed and nest inside the tied or folded leaves until mid- to late May, when they begin to pupate. [2] [3] [4] The larvae leave the trees to pupate, descending to the ground on silken threads. The pupae are commonly found in leaf litter on the forest floor beneath the oak trees. In late May or June, after one or two weeks in the pupal ...