Emergence of grape bud beetles from two Coachella Valley vineyards in 1983. The same emergence pattern occurred in different vineyards in 1984-86. Emergence traps show that about 10 percent of the beetles emerge by the first week in March with peak emergence in the latter half of March. Essentially all vineyards complete bud break before peak beetle emergence. Nearly 300 beetles emerged in some traps and only a few beetles in other traps in the same vineyard.

Illustration from Grape Pest Management, 2nd edition. UC ANR Publication 3343.