Together with R.J. Beck of the Tippecanoe County Health Department and one intern, 265 visits were made to habitats that supported mosquito larvae or were suspected of supporting them. Again, the visits stemmed from "call-ins" by the public, reports by city and county streets and parks personnel, and our continuing surveys conducted from roads and on foot.
Similar to 2003, the rainfall pattern, amounts of rain per rainfall event, moisture content of soils, and peeriodic flooding of streams resulted in the production of mosquito larvae nearly all season, starting in early May and continuing into early October. Flooding of dry land along the Wabash River and Wildcat Creek following record rainfall (over 10 inches in the Lafayette area) the second week of June led to hatching of Aedes and Psorophora eggs laid previously and within several days thereafter to tremendous numbers of larvae along extensive stretches. Again, as in 2003, larvae of Aedes trivittatus and A. vexans were found in nearly every site sampled and larvae of Psorophora ferox and P. horrida in certain sites. Larvae also were found in runoff catch basins, plus wheel ruts and numerous ground pools that filled with rainwater. Heavy rainfall in early July led to a second round of large numbers of Aedes and Psorophora mosquitoes in sites subject to inundation from rainfall and runoff.
Similar to 2003, Culex larvae were collected in a variety of standing water habitats starting in early May and large numbers were collected in runoff catch basins that held water for two weeks or longer following the record rainfall mid-June and subsequent flooding. Larvae of Culex restuans commonly were collected in ground pools and wheel ruts that contained decaying vegetation and in discarded tires starting in May and continuing all summer. Larvae of C. pipiens and C. salinarius were collected in similar sites starting in mid-June and continuing all summer, with very high numbers in runoff basins containing polluted water following the flooding and rainfall events mentioned above.