Six Mile Lake 2011 Summary

Weevil Biology  Native to North America and Long Lake  Original host plant is native Northern watermilfoil  Entirely aquatic, except for shoreline hibernation in winter  Larvae and Pupae stages have highest impact  Tunnel through stem, emerge as adults Eggs Larvae Pupa Adult

Weevil-Induced Damage  Nutrient flow disrupted  Loss of buoyancy = collapse  Reduced biomass & plant height  Secondary infections

EnviroScience Stocking Strategy  Stock multiple years  More weevils in first year  Concentrate weevil populations in a few locations  Annual surveys: evaluate progress  Seasonal variation

Year Sites Stocked Total Weevils 2009S16, S1, S2, S312, S1, S2, S316,000

Survey Components  Weevil population density  Milfoil density  Native plant species and relative abundance  Weevil activity  Overall health of milfoil  Long term data

2011 Positive Results Weevil life stages and damage found at all stocking sites 2011 results indicate an increase in weevil population Found weevils at S2 which was previously undetected in 2010 Milfoil density at S2 and S3 decreased by 75% and 50% post-stocking 2011 Milfoil is well-below surface of water (1-3 feet) in stocking sites S1 had a 50/50 mix of milfoil and native plants

Native Plant Species  Seven native aquatic plant species were recorded in 2011: Clasping leaf pondweed (Potamogeton perfoliatus), Chara (Chara sp.), Coontail (Ceratophyllum demersum), Eelgrass/Water Celery (Valisneria americana), Elodea (Elodea canadensis), Flat-stem pondweed (P. zosteriformis), Large leaf pondweed (P. amplifolius), Northern watermilfoil (Myriophyllum sibiricum), Sago pondweed (P. pectinatus), Thin pondweed (P. pusilus), White water-buttercup (Ranunculus aquatilus), and White water lily (Nymphaea spp.).

 Slow start to stocking  2011 Seasonal Variability  Expected Results  Milfoil growing below surface  Decrease in milfoil density and health  Increase in native plant species density Six Mile Lake Project Considerations

2012 Proposal  Association contract for 15,000 weevils  EnviroScience will match (30,000 total) for a more aggressive plan  Address additional areas of infestation  Comprehensive milfoil assessment  What you can do to help

(800) (330) Darrow Rd Stow, OH Contact EnviroScience