Damage should also be visible by now in the northern half of the state but not quite as far along. Damage by the larvae will increase as they get larger over the next two weeks. If you have not reached the threshold level, wait to resample for several reasons. Also, alfalfa weevils are susceptible to a fungus disease, which can decrease populations rapidly. The large amounts of rainfall and moderate temperatures over much of the southern and eastern parts of the state will favor onset of the disease.
Populations can crash within a week's time.
Fungal diseases cause infected larvae to crawl to the tops of the plants where the dead weevils will be easy to see. Lady beetles will feed on the smaller weevils, but will prefer aphids. If weevil populations have reached threshold levels and no fungal disease is visible, it is unlikely natural enemies will control them. Another alternative to chemical treatment is an early cutting of the alfalfa. In general, if threshold levels are reached and the chemical selected has a short enough harvest interval, it will pay to treat for alfalfa weevil.