(CBS News) Weather remains a problem for Dallas-area officials trying to combat mosquitoes carrying the West Nile virus.
Aerial spraying of insecticide was called off late Friday night due to rain. The same thing happened Thursday, the first night of the controversial spraying program.
No details were available about future spraying.
Joseph Conlon, a technical adviser to the American Mosquito Control Association, says only time will tell how effective the spraying will be.
"There's really no way of positively determining that until the season plays itself out," Conlon, a retired Navy entomologist with extensive worldwide experience in mosquito control, observed on "CBS This Morning: Saturday."
The Centers for Disease Control and Prevention says 26 people nationwide have died from it.
Texas is considered the outbreak's epicenter. Ten people have died there from West Nile, and more than 200 have gotten sick.
"This is just the beginning of the West Nile season," Conlon pointed out. "The last five years by this time, we had an average of about 172 cases of West Nile" across the U.S.
This year, there are nearly 700 cases spread across 43 states. "That does not bode well for the future. We're only the beginning the season," Conlon said.
But he downplayed worries that the pesticide that's been sprayed over Dallas could itself harm people's health, saying that, while he "can understand peoples' concerns ... the insecticides they're using have been fully evaluated by the EPA (Environmental Protection Administration) and have been deemed to not pose an unreasonable risk if they're utilized according to the label."
Holding up a tiny test tube half-filled with liquid, Conlon said that's all that's being sprayed per acre in Texas, and the active ingredient that kills the mosquitoes is "a little less than two grams," which is about the same weight as two stamps. "So we're not talking about a lot," Conlon stressed.
To see the entire interview, click on the video in the player above.