Concrete dams, which do not have any steel reinforcement, have a much longer service life than reinforced concrete struc-tures exposed to weather. The oldest concrete dams are about 120 years old. masonry dams can be much older and still be in service.ut at the same time, it can also be very short if some of the safety-relevant elements are no longer functioning properly.an example for uncontrolled safety decrease is the 272m high Enguri arch dam (the worldâs highest arch dam) in Georgia, which was completed in 1984.
As it turns out, mosquitoes do play an important role in a variety of ecosystems. For example, each year when the snow melts in the Arctic tundra, mosquitoes hatch from their eggs and make up a significant part of the biomass. Some scientists believe these insects serve as an important food source for migratory birds.
Rearing of Insects. The goal of organized insect rearing is to provide reliable, affordable sources of high-quality insects for their many important purposes. We are now able to rear literally thousands of insect species through multiple generations and many more for part of their life cycles.