A MEMBER: Will birds or any kind of poultry eat them?
DR. ADAMS: Yes, poultry will eat them, as far as they can reach. Certain birds, of course, will feed on them to some extent, but birds, in summer, seem to have plenty of other things to eat, and they certainly leave plenty of beetles in plain sight uneaten. We can see that the birds are a fairly constant helpful factor, but are not to be relied upon to prevent injury occurring in a beetle outbreak.
Rotenone, which, I believe, is one of your main insecticides in nut culture, is fairly effective on Japanese beetles. It kills the beetles hit with the spray and gives protection for several days thereafter. If you apply it often enough, rotenone can take care of the plants so that they don't become disfigured by the beetles. Using cube powder, you may apply five ounces of 4% rotenone in 10 gallons of water. Of course, in many cases there is no objection to using DDT wetable powder or dusts, unless you are afraid of a mite problem arising after DDT is used. If DDT can be sprayed on the plants, it needs to be applied only about three times during a summer, or sometimes only twice. For plants that are growing very fast, the new growth, of course, has to be kept treated. You may prefer to spray once heavily over all the plants in July and then, after that, keep the beetles off by spraying or dusting the new growth, during August. For more directions see U.S.D.A. Farmers Bulletin No. 2004.
Now, there are new chemicals that will kill Japanese beetles very quickly. Parathion will kill them, but its toxicity necessitates great care in handling and, on peaches, we find it protects the plants for only a few days. Chlordane, which has a very important use in connection with these insects in the grub stage, is not recommended above ground; it is too brief in its action. Methoxychlor may be used instead of DDT. It is less effective, but much less poisonous, and should be applied more frequently.
Now, the other aspect of control is to try to reduce beetle production over the whole area so that you don't have so many beetles flying in to the plants during the summer and you don't have to spray so frequently, if at all. This is the phase to which I wish to give particular attention, after we consider the life history.