1. STRAITS POND MIDGES:Biology, Ecology, and Problem Populations

2. Straits Pond inhabitants: • Anadromous/Catadromous/ Amphidromous fish • Migratory shorebirds and waterfowl • Invasive plants and animals • Ailanthus altissima • Phragmites australis • Swans Three-Spined Stickleback

3. Invasive plants … Tree of HeavenAilanthus altissima

4. Invasive species …

5. Straits Pond invertebrates: • Aquatic beetles • Dragon/Damselflies • Familiar Bluet • Big Bluet ? • Seaside Dragonlet • Needham’s Skimmer ? • Periwinkle Littorina sp. • Green Crab C. meanus Uvarus sp. COLEOPTERA: DYTISCIDAE

6. Skimmer Dragonfly Larva ODONATA: LIBELLULIDAE

7. Flies (Diptera) No-see-ums (Ceratopogonidae) Greenheads (Tabanidae) Craneflies (Tipulidae) Midges (Chironomidae) Straits Pond invertebrates:

8. MIDGES • Abundant and ubiquitous • Inhabit all aquatic habitats • Adults do not bite • Significant food source for many other species • Pollution-tolerant

10. Midge Taxonomy • Insect order Diptera, or “True Flies” • Family Chironomidae • 20,000+ species • >350 sub-families • >2,000 spp in N.A.

11. Aquatic dipteran larvae Merritt & Cummins, 1996 Aquatic Insects of N. America

12. GENUS:Chironomus C. decorus C. riparius C. plumosus C. dorsalis >20 spp. in N.A. • Multivoltine - produce 1 to 4 generations each year • Larvae are detritivores • Larvae burrow, build U-shaped tubes • Protection • Respiration • Body fluids contain high-affinity hemoglobin

13. Chironomus life cycle • Eggs hatch within 3 days • Larvae live 5 - 50 days • Temperature • Food availability • Depth preferences • Overwinter in bottom sediments in mid-larval stages

14. Chironomus larval ecology • Associated with soft upper sediment layers • Densities correlated with organic content • Consume bacterial and fungal components • Lower densities found in gravel (ponds) • Relatively drought and freeze tolerant • Do not migrate during dry/cold spells

15. Pupal stage www.first-nature.com • Brief - 2 to 5 days • Remain in larval tube • Float to surface before emergence

16. Pupal stage Merritt & Cummins, 1996 Aquatic Insects of N. America

17. Adult stage www.first-nature.com • Adults live a few days to weeks • Feed on nectar, or do not feed • Females produce one batch of eggs

18. Adult stage Merritt & Cummins, 1996 Aquatic Insects of N. America

19. Super Floss Chironomid Courtesy of Washington Fly Fishing Gallery www.washingtonflyfishing.com

20. Factors contributing toproblem populations: • Stagnation • Warmer temperatures • Lower Dissolved Oxygen concentration • Nutrient loading • Septic systems and fertilizers … N, P, K • Decayed algae and plants … C

22. Annoying swarms gather in backyards Adult midges are attracted to lights Food is abundant Larvae thrive in harsh environments Beware of “bug-zappers” Attract more insects Kill beneficial spp. Use yellow bulbs Reduce nutrient sources Lawns/Septic systems Decaying plant material Circulate/aerate water Problems & Suggestions

23. Alternative control methods • Manual removal of detritus • Bacterial breakdown of organic sediments

24. Alternative control methods • Wind or solar powered water aeration • Introduce predators • Dragonfly larvae? • Bream

25. Estimated percentages of aquatic invertebrate taxa Figure 1. Freshwater streams

26. Estimated percentages of aquatic invertebrate taxa Figure 2. Tidal ponds

27. Midge Predators • Fish • Feed on aquatic stages • Most effective predators • Waterfowl • Feed on aquatic stages

28. Midge Predators • Dragons and Damsels • Consume all stages • Charismatic • Diving Beetles • Voracious consumers of aquatic stages • Tolerant, prolific • Microorganisms • Fungi, Bti

29. Seaside Dragonlet Erythrodiplax berenice

30. Needham’s Skimmer Libellula needhami

31. Midge Predators • Swallows and Swifts • Forage on mating swarms • Bats • Feed in open areas

32. Looking ahead … • Monitor beneficial organisms • Vertebrates • Invertebrates • Promote scientific research • Local schools • UMass Boston (Biology, ECOS)? • Adapt