Aedes is the best represented mosquito genus in California in the number of species. Many species in this genus are commonly referred to as floodwater mosquitoes because eggs are laid in sources that will eventually fill with water. Aedes eggs are laid singly at the edge of drying substrate. They are resistant to drying out and may require a conditioning period before hatching. Larvae have a short siphon and hang downward at a 45 degree angle from the water surface. Adults have a pointed abdomen and rest with their bodies parallel to the surface. Most Aedes adults readily feed on humans and are aggressive biters. Several species are capable of transmitting diseases to humans including dengue, yellow fever, chikungunya, and many others. Aedes sierrensis is the primary vector of dog heartworm in California. Twenty seven Aedes species are recognized in California, one of which, Ae. atropalpus, has only been collected once near Folsom, CA. Two species, Ae. albopictus and Ae. aegypti, are not included in this total although they have been introduced into California several times. The most recent introductions occurred in 2011 (Ae. albopictus) and 2013 (Ae. aegypti). Efforts to eradicate these mosquitoes are ongoing.