Item Package Quantity:5 Here's how it works. Simply place the Fruit Fly Bar Pro in the problem area, whether it's a drain, dumpster, kitchen, bathroom, locker room, office or anywhere else. Once you've removed the Fruit Fly Bar Pro from its foil package, the air activates a pest controlling, time release vapor. Within about 24 hours, this vapor has worked its way into the pests' hiding and resting spots, killing all the bugs in the area. This vapor can remain effective for up to four months in a 220 cubic foot space. The vapor poses no danger to humans and pets in the area. The dose of the active ingredient (Dichlorovinyl Dimethyl Phosphate, or DDVP) is so incredibly small that it's only a risk to creatures the size if an insect. In addition to controlling fruit flies, Fruit Fly Bar Pro kills off cockroaches, spiders, mosquitoes, bed bugs, moths, silverfish, earwigs and more.