Bosvogels

The hemlock woolly adelgid (HWA), a native of Asia, a 1/32 inch long reddish purple insect that lives within its own protective coating, is a threat to eastern hemlock forests, and eastern and Carolina hemlock of all sizes are susceptible. The HWA came from Asia without any of the natural enemies that keep populations in check in its native range. HWA was first reported in the eastern US in Virginia in the mid 1950's. Since then, it has spread north to Connecticut and south through North Carolina. It reached eastern Tennessee in 2002, and was first reported in eastern Kentucky in spring 2006. Systemic insecticides containing the active ingredient imidacloprid can be used as soil drenches or injections to control the HWA.

There are multiple ways that plants in urban landscapes can contain imidacloprid-contaminated nectar, since it is commonly applied in the landscape for many pests and many greenhouse plants are treated with prior to sale and transplanting. Imidacloprid may persist in nectar for a long time, since soil applications were effective against foliar pests for 1 to 2 years in containers and landscape trees. Injections of concentrated volumes of imidacloprid applied to trees trunks and roots were effective for 12 months for ash and linden. A soil application of imidacloprid to Eucalyptus tree resulted in 500 ppb in nectar and pollen, which will kill any insect feeding on nectar and pollen. Tree injections of imidacloprid at flowering are cause for concern, since linden flowers are a good source of nectar and pollen for bees, butterflies, and other beneficial insects.

Nearly all shade trees and many shrubs are subject to borer attack, the tunneling of immature beetle or moth larvae through the cambium, sapwood or heartwood of the host plant. The emerald ash borer is now one of the most destructive non-native insects in the United States. The potential damage of this insect rivals that of Chestnut blight and Dutch Elm Disease. Since its accidental introduction into the United States and Canada in the 1990s, and its subsequent detection in 2002, it has spread to 14 states and adjacent parts of Canada. It has killed at least 50 to 100 million ash trees so far and threatens to kill most of the 7.5 billion ash trees throughout North America. Traditionally, borers have been treated with a trunk spray application of insecticide that kills the newly hatched insects before they tunnel into the plant. However, imidacloprid, a systemic insecticide that is applied as a soil drench around the base of target plants, is making borer control easier and targeting the small larva as they chew their way into the plant. It has a twelve-month residual effect. The chemical is absorbed by the plant's root system and moved throughout it's trunk, branches and foliage.

Soil injections of imidacloprid are effective at preventing attack by the walnut twig beetle, a very aggressive beetle that will attack both healthy and stressed trees. Imidacloprid can also be injected directly into the trunk or soil so there is no public contact. Soil injections of imidacloprid are also very effective against Elm leaf beetles, a cyclic pest, European elm scale, one of the most widespread and destructive scale insects, Hawthorn mealybug and Kermes scale, which affects pin oak and red oak trees.

For almost 60 years the Baden-Württemberg forestry administration has been documenting the results of its nestbox monitoring scheme. The number of boxes rose from 40,000 around 1950 to 180,000 in the 1980s/1990s. For this study, 80,412 successful nests of the Tree Sparrow Passer montanus were evaluated out of the 3,4 million nestboxes monitored up to 1996. Since the Tree Sparrows in this survey mostly breed at woodland edges, but forage almost exclusively in agricultural land, the results reflect the general trend for the species in SW Germany. Until 1971 the species bred with constant occupancy rates that varied regionally between 0.5 and 5 % of all nestboxes. After that year the proportion increased, reaching rates of 15 % in the Rhine Valley and regionally of more than 30 %. After 1980 the nestbox population collapsed; the drop in the intensively cultivated Rhine Valley was from 15 % to 2 %. The increase in the 1970s is thought to have resulted from the prohibition of DDT. The permanent and continuing decline since 1980 indicates that developments in agriculture have been responsible for the later long-term negative population trend. Areas of intensive agriculture below an altitude of 200 m show the highest rates of decline.