Richard S. Cowles


Valley Laboratory
The Connecticut Agricultural Experiment Station
153 Cook Hill Road
Windsor, CT 06095
Voice: (860) 683-4983 Fax: (860) 683-4987

Expert in the area of biology and management of spotted wing drosophila, hemlock woolly adelgids, armored scales, white grubs (Japanese beetle, oriental beetle, European chafer, Asiatic garden beetle and black turfgrass ataenius), black vine weevil, and spider mites. Experienced in the uses of conventional and new insecticides for the management of nursery, turf, landscape, and small fruit pests.

B.S. Entomology Cornell University 1982
M.S. Entomology Michigan State University 1986
Ph.D. Entomology Michigan State University 1990

Station Career:
Assistant Scientist, Associate Scientist and Scientist, Valley Laboratory, 1994 – present
Agricultural Scientist

Past Research:
Previous research has involved behavioral manipulation of pests to effect a more favorable distribution of egg-laying into diversionary crops, identification of a clearwing borer pheromone, and chemical or biological control of several strawberry, floriculture, nursery, landscape, and forestry pests. Breakthroughs have included effective and IPM compatible treatments for twospotted spider mites, white grubs, and black vine weevils in nurseries; white pine weevil, pales weevil, balsam twig aphid, and armored scales in Christmas tree plantations; hemlock woolly adelgid and elongate hemlock scales in forests; annual bluegrass weevil on golf courses; dust formulation insecticides for targeting bed bugs; and developing a strawberry variety tolerant of black root rot and black vine weevils.

Current Research:
Current research efforts are directed toward improved management of armored scales in Christmas tree plantations through basal bark sprays of systemic insecticides; improving the genetics of fir trees grown as Christmas trees; and finding alternative and more effective options for managing strawberry sap beetles and spotted wing drosophila, especially by including behavioral manipulation.

Selected publications available from author,

Christmas Tree Pest Management

  • Cowles, R. S. (2020). Sulfur amendment of soil improves establishment and growth of firs in a field naturally Infested with Phytophthora. J. Environ. Hort. 38(1),15–21. (PDF)
  • Practical Armored Scale Management. The following article is available courtesy of The American Christmas Tree Journal, Volume 55, Number 4, pages 12 – 15, with permission from the National Christmas Tree Growers’ Association. (PDF)
  • Cowles, R. S. 2020. White pine weevil management. Great Lakes Christmas Tree Journal 16 (1): 28-30. (PDF)
  • Cowles, R. S. 2020. Zimmerman pine moth biology and management. Great Lakes Christmas Tree Journal 16 (1): 20-21. (PDF)

Systemic Insecticides 

  • Cowles, R. S. and Eitzer, B. D. (2017). Residues of neonicotinoid insecticides in pollen and nectar from model plants. J. Environ. Hort. 35(1), 24–34. (PDF)
  • Cowles, R. S., Rodriguez-Saona, C., Holdcraft, R., Loeb, G. M., Elsensohn, J. E., and Hesler,  S. P. (2015). Sucrose improves insecticide activity against Drosophila suzukii (Diptera: Drosophilidae). J. Econ. Entomol. 108(2), 640-653. DOI: 10.1093/jee/tou100. (PDF)
  • Cha, D.- H., Hesler, S. P., Cowles, R. S., Vogt, H., Loeb, G. M., and Landolt, P. J. (2013). Comparison of a synthetic chemical lure and standard fermented baits for trapping Drosophila suzukii (Diptera: Drosophilidae). Environmental Entomology, 42, 1052-1060.
  • Harper, R. W., and Cowles, R. S. (2013). Susceptibility of Chinese hemlock (Tsuga canadensis) to injury from autumn horticultural oil applications. Arboric. & Urban Forestry, 39, 6–10.
  • Anderson, J. F. and Cowles, R. S. (2012). Susceptibility of Cimex lectularius (Hemiptera: Cimicidae) to pyrethroid insecticides and to insecticidal dusts with or without pyrethroid insecticides. J. Econ. Entomol. 105(5),1789-1795.
  • Cloyd, R. A., Bethke, J. A. and Cowles, R. S. (2012). Systemic insecticides and their use in ornamental plant systems. Floriculture and Ornamental Biotechnology, 5(1), 1–9.
  • Cloyd, R. A. and Cowles, R. S. (2010). Pesticide rotations and mixtures: which is best for resistance mitigation?  OFA Bull. 923: 19–20.
  • Cowles, R. S. (2010). Optimizing a basal bark spray of dinotefuran to manage armored scales (Hemiptera: Diaspididae) in Christmas tree plantations. J. Econ. Entomol. 103: 1735–1743.
  • Ramoutar, D., Cowles, R. S., Requintina, E. Jr., and Alm, S. R. (2010). Synergism between demethylation inhibitor fungicides or gibberellin inhibitor plant growth regulators and bifenthrin in a pyrethroid resistant population of Listronotus maculicollis (Coleoptera: Curculionidae). J. Econ. Entomol., 103 1810 – 1814.
  • Cowles, R. S. 2009. Optimizing dosage and preventing leaching of imidacloprid for management of hemlock woolly adelgid in forests.Forest Ecology and Management 257: 1026 – 1033.
  • Cowles, R. S. 2004. Susceptibility of strawberry cultivars to the vine weevil (Coleoptera: Curculionidae). Agric. & Forest Entomol. 6: 279 – 284.
  • Cowles, R. S. 2004. Effects of azadirachtin on the reproduction of the vine weevil (Coleoptera: Curculionidae). Agric. & Forest Entomol. 6: 291 – 294.
  • Cowles, R. S. 2003. Modeling the effectiveness of bifenthrin for protecting container-grown crops from Japanese and oriental beetle larvae. J. Environ. Hort. 21: 78 – 81.t
  • Cowles, R. S. 2001. Protecting container-grown crops from black vine weevil larvae with bifenthrin. J. Environ. Hort. 19: 184-189.