Stethorus/Spider Mite Destroyer
Coccinellidae
Scientific Names
Stethorus punctum punctum (LeConte) and Stethorus punctillum Weise
Identification
Both species are lady beetles.
Eggs:
- White, oval and less than 0.5 mm long, and turn blackish just before the larvae emerge
- Laid singly
Larvae:
- 2 mm in size, gray to blackish and is covered with short, branched hairs
- As the larva matures it becomes reddish, at first on the edges of the body and eventually entirely
Pupae:
- Black and flattened
- Somewhat pointed on the posterior end
- Entire body covered with yellow hairs
Adults:
- Small (1.5 mm) shiny black beetles that are covered with sparse, fine yellowish to white hairs
- This is the lifestage seen most frequently in vineyards
Often Confused With
N/A
Interaction With Host
Both species described above fill a similar role as biological control agents. Stethorus punctum can be found feeding on spider mites in a variety of crops including vineyards. There are 2-4 generations of S. punctum each year.
Peaks in larval activity are dependent upon mite populations. There are usually three overlapping generations per year. The total time for development from egg to adult is 23 days. Adults feed for an average of 25 days before beginning to lay eggs.
Period of Activity
Spring to late summer.
Insects Attacked
Larvae and adults are important predators of European red mite.
Monitoring and Management
Beetles consume all stages of mites; adults can consume 75 to 100 mites per day and large larvae can devour up to 75 mites per day, so they quickly lessen an outbreak of spider mites.
Adults are easy to see with the naked eye.
