Many insect events correlate with the blooming of Vanhoutte spirea, Spiraea x vanhouttei, which is occurring in central Illinois. The following information from the book Coincide should help practitioners plan scouting activities.
- Birch leafminer: Look for small mines when blooming starts.
- Pine needle scale: Red crawlers are active when blooming starts.
- Taxus mealybug: Nymphs are active during blooming.
- Lilac/ash borer: Egg hatch begins in full to late bloom.
- Oystershell scale (brown race): Crawlers hatch and are active in full to late bloom.
- Oystershell scale (gray race): Crawlers hatch when blooming finishes.
- Black vine weevil: Look for feeding notches as blooming finishes.
- Bronze birch borer: Egg hatch begins when blooming finishes.
- Elm leaf beetle: Feeding damage will begin to occur as blooming finishes.