These insecticides kill the cock- 
roaches present and leave a residue 
on the treated surface. The residue 
does not keep cockroaches out, but 
those that come in contact with it 
are killed. A single treatment in the 
right places gives protection for 
several weeks. 
A liquid insecticide is often the 
best for use in the home. A dust or 
water-base spray may be used when 
there is danger of fire from oil-base 
liquids. Both a liquid and a dust 
may be used when cockroaches are 
abundant, difficult to control, or 
firmly established. 
Baygon, trichlorfon, and fenthion 
are effective, but application of tri- 
chiorfon and fenthion is lmited 
to spot treatment by professional 
pest-control operators. 
APPLICATION 
Whether spray or dust is used, 
treatment should be limited to base- 
boards, cracks, and places where 
roaches hide. 
Spray 
Apply a liquid insecticide with 
an ordinary household plunger- 
type sprayer that produces a coarse 
spray to wet the surface being 
Mention of a proprietary product in 
this publication does not constitute a 
guarantee or warranty of the product by 
the U.S. Department of Agriculture and 
does not imply its approval by the Depart- 
ment to the exclusion of other products 
that may also be suitable. 
BN—2288 
Female Australian cockroach. (144 times 
natural size.) 
treated. If the mist is too fine, it will 
float away in the air. Apply enough 
spray to moisten surfaces thor- 
oughly, but not so much that the 
liquid begins to drip or run. 
Professional pest-control opera- 
tors may use larger sprayers, but 
should make spot treatments only. 
A paintbrush may be used for 
applying the liquids in cracks or 
along baseboards. 
Dust 
Apply an insecticide dust with a 
puff duster of the bulb, plunger, or 
bellows type. Blow the dust into 
hiding places that are hard to reach 
with a spray and onto surfaces 
where roaches run. A light, uniform 
film is sufficient. Repeat when mois- 
ture causes the dust to cake. 
Placing a band of dust on the floor 
around the edges of a room is not an 
adequate treatment. Many roaches 
may be able to go from their hiding 
places to sources of food and water 
without crossing the band of dust. 
