Typical San Joaquin Valley mosquitoes thrive in the hot, dry climate that is typical during the summer. But the humid weather of the past several days has created the perfect biosphere for a pair of pests that has experts on edge after being discovered over the course of the past year in southern parts of the state. The Yellow Fever Mosquito and the Asian Tiger Mosquito – neither of which have been detected yet in San Joaquin County – are both known to thrive in humid conditions, and both carry potentially deadly diseases like yellow fever, dengue fever and chikungunya.