The latest plague to befall Colorado is the Japanese Beetle. Last year I saw a few on my raspberries. This year they're all over. Dealing with them has become the stuff of folklore with everyone having their favorite method.
Use Organic Neem oil; some are pretty sure this works. Use inorganic Neem oil; there seems to be more certainty about that especially when mixed with Dawn detergent. Possible drawback is that it affects the bees as well.
Malthion 50 works for certain if you don't mind that is works equally well on anything with too many legs.
Traps are popular with some but the caveat is that since they are based on an attractant, the ones that don't make it all the way to the trap wind up on your plants. To the observation of myself and my neighbor, the traps work over a wide area and will eventually deplete the population. The joke goes that we should each buy a six-pack of traps and give one to each of our neighbors thus creating a safe zone in the middle.
I got several hundred right away and am now getting much fewer so good. The gardeners say to empty the traps into a bucket of soapy water to kill the little bastards off. What they forgot to mention is that 5-700 Japanese beetles, even in soapy water quickly begin to stink. Note to self: Empty the trap into the bucket, then soon empty the bucket into the toilet.
Milky Spore is a longer term defense as the bacteria attack grubs in the ground. It takes 2 years to become established, and is not available here as the Colo Dept of Agriculture does not yet recognize the JB as a notable pest.
If I had a lower growing crop than the raspberries, I'd fence them off and borrow some chickens from the urban farmer up the street. The chickens think the JB's taste like candy.