34 
THE COLORADO EXPERIMENT STATION 
9 . WHITE HELLEBORE. 
Hellebore, as obtained from drug stores, is a light, yellowish- 
brown powder. It is a vegetable poison and is obtained by pulver¬ 
izing the roots of an European plant Vercttrum album. It is not as 
poisonous as the arsenites and consequently it is not as effective in 
the destruction of most insects, but it has its special uses. Slugs, 
which are the young of saw-flies, are particularly susceptible to its 
effects. The poisonous property is an alkaloid and it loses it virtue 
after being exposed to the air for a few days. For this reason it 
can not be used where it is likely to remain long before being 
eaten, and it must be kept in tight receptacles and must not be 
kept too long before using. It is often useful for the destruction 
of insects upon plants containing fruit that will soon be used for 
food. 
Dry applications are easily made upon low plants by making a 
small cheesecloth sack, through which the dust may be sifted 
lightly over the foliage. The best tim e to apply is in the evening 
I11 the wet way use: 
White hellebore.1 ounce. 
Water. 3 gallons. 
Apply as a spray in the evening. 
10 . BORAX. 
Used chiefly for the destruction of cockroaches. Spread the 
powdered borax upon bread, sweet potato or banana peelings, or 
mix with sweetened chocolate, and place the bait where the 
cockroaches can get at it. 
SUBSTANCES THAT KILL BY EXTERNAL CONTACT. 
Substances in this group are chiefly used against insects that 
take liquid food from beneath the surface of the plant by means of 
a tubular rostrum or beak, but they may be used against many 
other soft-bodied insects with success. Insects having a hard outer 
crust to their bodies resist these substances and are not easily killed 
by them. If insects are covered with a powdery or cottony material, 
the insecticide will have to be applied with considerable force to 
cause it to penetrate to the body. Applications must always be 
thorough, because only those insects will be killed that have the 
substances thrown upon them. 
II. SOAP. 
The ordinary soft soaps and laundry soaps have long been 
used for the purpose of killing vermin on plants and animals, and 
