brass tacks, I can attest to the effectiveness of fresh neem leaves in keeping weevils out of stored rice (jute bags or wooden barrels). The leaves were replaced regularly as they dried out.

One way is to mix in some Diamotaceous Earth, food grade not pool grade, which has sharp edges that cut the weevils so they "bleed" out. For the grains used in the kitchen that simplest method of control is to freeze those grains, flour, corn meal, whatever.
Our USDA a few years back decided to allow larger numbers of feces and eggs in these grains (and since your Alfalfa pellets are meant as animal, not human, food this rule does not apply at all) because it would cost the producers of these products too much money (lower profits) to screen them better.

Seal/store the bags in tightly sealed container such as a garbage can. It works for me.

I ditto the use of food grade DE. That's what has been used for a long, long time to protect grain foods from infestation, including what is used for human consumption. Small amounts of it is found in flours, meals, cereals, edible seeds, and nuts.

That's interesting about the neem leaves, ronalawn.

Is the alfalfa pellets just alfalfa or does it have grain additives? You should handle each differently because the pests that attack will probably be different. Less grain type product just leafy vegetative matter in alfalfa pellets. Rabbit pellets which some people call alfalfa pellets are mixed with grain.

Also what is your intended use, feed, soil addition?

"Is the alfalfa pellets just alfalfa or does it have grain additives"

Most Alfalfa pellets are made by grinding up the foilage and "extruding(sp?)it" via high pressure...same way as some pasta forms (except it is cut into small pieces instead of long pieces). They don't need a binder, the high pressure creates heat, sticking it together. The "rabbit pellets" are made the same way, just different ingredient's (some organic fertilizers are made this way also...very common)

Schmoo

Yep, the only grain product in the alfalfa pellets is perhaps seeds of the plant. Unlikely to get weevils. There are lots of other bugs that eat foliage but not the common grain weevil. I do have a problem with a large gnat/small fly that will lay eggs and the worms will eat any vegetable matter.

Depending on what you were going to use the stuff for you should have few problems.

If you never have any kind of insect infest your Alfalfa pellets, grain pellets, or what ever it has either been sprayed with an insecticide so heavily as to be poison now or is dead and not a worthwhile food source for either animals or the soil. Any product worth using in the garden should be attractive to insects of many kinds, including "weevils". All grains are seeds, and all seeds have all the "stuff" needed to grow into whatever the seed is supposed to be and is therefore, unless poisoned, very attractive to many insects.

Brass Tacks,

I will third the DE recommendation, even used in commercial grain silos and has an incredibly long history in pest control (even inside farm and companion animals...worms,etc.)

kimmsr,

Please take your blinders off once and awhile...there is a much bigger world when you don't have such a narrow focus.

Schmoo

kimmsr, Sorry I have been around many alfalfa bales and have never seen or heard weevils in them. Lots of other things but not weevils. Most hay is cut before the seeds harden. Therefore the seed/grain should not be there.

Visit a farm with alfalfa hay in the spring before the first cutting. I sincerely doubt if you will find weevils. If they are in the pellets then the DE might work. Since I have lung problems I do not recommend DE because it becomes airbourne too easily.

Alfalfa weevils can be a major problem.

Here is a link that might be useful: About Alfalfa weevils

Interesting article it appears that the alfalfa weevil is a green feeder.