Methoprene is a IGR, (insect growth regulator) used in quite a few spray products. It also goes by the name "Precor". Some products also mix kill agents like permithrins, but you can buy spray which is only methoprene but you have to read the lable.
I like the products that are only methoprene, because the amount needed for flea or tick control is minimal, and in order to have so much there was any toxicity to humans or animals would take more than you can get in higher concentration than a whole can of the stuff.
We accidently brought a flea infestation home with about 3 ticks after a trip to the hills one time. I worked in the pet product industry at the time, and used precor spray all through the house on carpet and floors and furniture, and also used a precor spray outside in the yard. We had no after infestation at all.
One other plus on methoprene is it lasts for 180 days. During that time, any flea or tick cannot go to the next stage of the life cycle. Eggs don't hatch right, larve cannot grow, and adults cannot lay viable eggs. Ticks will die if they cannot grow. We always used something on the tick bite to prevent infection.
"Shivers"............................. I hate ticks, they disqust me, and fleas can get out of control in almost no time at all.
I have, but do not like to use any pill or oil application for the dogs, as some of these have bad reactions. I would rather just know they can't bring hitch-hikers home to get started and give the dogs a good exam after we have been out. If you have a dog that is regularly exposed, a coller with a methoprene and less toxic kill is warrented.