Several available insecticides work if you can get the timing right. Carbaryl (Sevin) will work, but its life is so short that it get the ones working today, but uneffective on the ones that move in tomorrow. Malathion is more effective over several days. Here they seem to be worse early. Planting for September harvests often are minimally or non stung by the curculio. Cyluthrin (Bayer Bioadvanced) should also work.