Japanese Beetles - Garden Pests

Japanese beetle traps alone are not effective enough in zones of greatest beetle abundance to protect favored food plant foliage. Spraying with lead  arsenate is also advisable. Such spraying is effective  to protect foliage but is less effective than traps for  reducing the number of beetles present and prospective. Certain essential requirements must be fulfilled  to secure best results with traps as follows: 

In a trap like the illustration use the bait described below. Choose a location where wind will carry the  odor toward the beetles and thus attract them to the  trap. They fly against the wind. Do not place the trap  so close to plants that the beetles will alight on nearby foliagesay 10' to 20' away from nearest trees  and shrubs. Locate each trap in full sun, as beetles  rarely enter traps in the shade. Hang it from a cross-arm from a pipe post so its funnel will be 3' to 4'  above ground and so the beetles will not hit the post  when flying toward the trap. 

The trap form and dimensions are shown in the picture. Both funnel and baffle are made of 30-gage  dull galvanized iron soldered smoothly together, the  central section of the latter cut away to allow the bait  bottle with its 30.5-gage perforated tin plate container to fit in. The ends of the container are fitted  with covers, the lower soldered in place, the upper  removable. 
 

The beetle container consists of a two quart mason jar whose ring-cover is soldered an inch above the lower  end of the funnel. The jar should have a small drainage hole bored in the bottom. To bore this a 60-grain, 6"  electrolon wheel %s" thick run at 10,000' a minute  is best. It is necessary to direct a fine stream of water  where the cut is to be made while the jar is held  against the wheel with moderate pressure; otherwise  the jar will crack immediately. 

A 10-gage galvanized iron bail handle inserted through two holes in the top of the funnel and looped  in its middle is used to suspend the trap from a hook  on the support. 

As many beetles attracted to the trap strike the funnel outside and escape, a trap with openings in the  funnel will reduce such losses, so four openings may  be made in the funnel 2y2"wide at the bottom, 2f/211  high and 4" wide at the top. The baffle is extended to  the bottom of the aperture, or 4y2" into the funnel.  Each flap is 1%" long projects inward at a 35'  angle with the side of the funnel, the diagonal edges of  the flaps engaging the wings of the baffle. If the flap  does not fit tightly against the baffle at these points,  beetles entering from above will get a foothold and may  escape. This trap will catch a larger percentage of  beetles than the trap without such openings. 

The outside of the trap should be painted light green; the baffle, bait container and inside of the funnel, white. Traps painted thus catch more beetles  than those painted otherwise. As the geraniol in the  bait makes the paint peel from the bait container the  paint should be resistant to alcohol. 

Geraniol used in the bait must not be confused with geranium oil which is far less attractive to the beetles.  Eugenol smells like clove oil llut is much stronger so  should always be used. When liquid bait is used it is  placed in 1%ounce bottles not more than 13/4" in  diameter, otherwise they will not fit in the containers.  The height should not exceed 3" else the wick will  contact the top of the container. Cotton lampwick is  passed through ,a cork and exposed about 2". If  larger, evaporation will be too rapid; if too short,  fewer beetles will be attracted. A bottleful should  last five to seven weeks, depending upon the weather.  Any bait left at the end of the season may be kept  until the next in a tightly corked amber-colored glass  bottle. The formula proportions for liquid bait are:  Geraniol (at least 70% pure), 4 teaspoonfuls; eugeno1 (U. S. P.), 1/4 teaspoonful; water, 1 tablespoonful. Pour into an amber-glass bottle, shake vigorously then fill the trap-bottle. 

As beetles are active during the day remove them from the traps late in the evening or early in the  morning while more or less torpid, dumping them  into a pail of very hot water or water in which is  some kerosene or gasoline. If beetles from several  traps are emptied into one pail stir them up to get  them wet. Keep the pail covered until all are dead.  Many beetles may appear dead when the jars are  opened on warm days. Take nothing for granted: kill them anyway! Beetles killed with hot water may  be fed to poultry or used as fertilizer scattered thinly  over the ground. 

For information as to manufacturers of traps and materials write the Japanese Beetle Laboratory, Bureau of Entomology, Moorestown, N. J. 

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See Also: Garden Pests