Cereal leaf beetle growth and population development can be tracked using a simple temperature-based model. Based on the temperatures in Salisbury, NC, this week (March 5-11, 2023) should be the time of peak egg-lay for cereal leaf beetle. On average, peak larval densities follow 17.7 days later, corresponding to the week of March 19-25. However, given the cooler forecast for the rest of this week, peak larval densities might be the last week of March.

We also ran the model for Lumberton and Plymouth. Both of these locations have experienced much more heat than Salisbury and should be well past peak egg lay at this time. If growers in eastern North Carolina have not seen cereal leaf beetle yet, there is a good chance that they will not in 2023. This tracks well ahead of the 30-year average.

Once peak egg-lay occurs, many fields will need only a single scouting for eggs and larvae. Wait about a week following the peak egg lay. If the proportion of eggs in the sample is 50% or greater then sample again in 5-7 days.

Learn more about CLB identification and scouting:

Insecticides are effective only on the larvae, not the eggs. Keep in mind rain and other weather events can kill eggs. It’s better to time your spray when a few small larvae have hatched. The threshold is 25 eggs plus larvae total per 100 tillers (this is an average of one per each of four tillers or 0.25 eggs plus larvae per tiller).

Any insecticide sprayed prior in February will not have an effect on cereal leaf beetle. Insecticide sprayed after this date might only slow the rate of infestation down. So it’s a good idea to scout your fields even if you’ve sprayed. Remember that cereal leaf beetle can still overwhelm your field if they invade in high densities. Insecticide residual for this insect runs out after about a month.

Cereal leaf beetle tends to be worse in thin stands. Contrary to common opinion, this is not because cereal leaf beetle prefers thin wheat (they actually prefer thick and healthy wheat), but because there are simply more beetles per tiller in thin stands compared to thick ones.

Learn more about cereal leaf beetle control methods: