Monarch butterflies () are familiar herbivores of milkweeds of the genus , and most monarchs migrate each year to locate these host plants across North American ecosystems now dominated by agriculture. Eastern migrants overwinter in high-elevation forests in Mexico, and western monarchs overwinter in trees on the coast of California. Both populations face three primary threats to their viability: () loss of milkweed resources for larvae due to genetically modified crops, pesticides, and fertilizers; () loss of nectar resources from flowering plants; and () degraded overwintering forest habitats due to commercially motivated deforestation and other economic activities. Secondary threats to population viability include () climate change effects on milkweed host plants and the dynamics of breeding, overwintering, and migration; () the influence of invasive plants and natural enemies; () habitat fragmentation and coalescence that promote homogeneous, species-depleted landscapes; and () deliberate culture and release of monarchs and invasive milkweeds.


Article metrics loading...

Loading full text...

Full text loading...


Literature Cited

  1. Agrawal A. 1.  2017. Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution Princeton, NJ: Princeton Univ. Press
  2. Alcock J, Brower LP, Williams EH Jr.. 2.  2016. Monarch butterflies use regenerating milkweeds for reproduction in mowed hayfields in northern Virginia. J. Lepidopt. Soc. 70:3177–81 [Google Scholar]
  3. Alonso-Mejía A, Arellano-Guillermo A, Brower LP. 3.  1992. Influence of temperature, surface body moisture and height above ground on survival of monarch butterflies overwintering in Mexico. Biotropica 24:415–19 [Google Scholar]
  4. Alonso-Mejía A, Rendón-Salinas E, Montesinos-Patino E, Brower LP. 4.  1997. Use of lipid reserves by monarch butterflies overwintering in Mexico: implications for conservation. Ecol. Appl. 7:934–47 [Google Scholar]
  5. Altizer S, Bartel R, Han B. 5.  2011. Animal migration and infectious disease risk. Science 331:296–302 [Google Scholar]
  6. Altizer S, Ostfeld RS, Harvell CD, Johnson PTJ, Kutz S. 6.  2013. Climate change and infectious disease: from evidence to a predictive framework. Science 341:514–19 [Google Scholar]
  7. Anderson JB, Brower LP. 7.  1996. Freeze-protection of overwintering monarch butterflies in Mexico: critical role of the forest as a blanket and an umbrella. Ecol. Entomol. 21:107–16 [Google Scholar]
  8. Barker JF, Herman WS. 8.  1976. Effect of photoperiod and temperature on reproduction of the monarch butterfly, Danaus plexippus. J. Insect Physiol. 22:1565–68 [Google Scholar]
  9. Batalden RV, Oberhauser KS. 9.  2015. Potential changes in eastern North American monarch migration in response to an introduced milkweed, Asclepias curassavica. See Ref. 112 215–24
  10. Batalden RV, Oberhauser K, Peterson AT. 10.  2007. Ecological niches in sequential generations of eastern North American monarch butterflies (Lepidoptera: Danaidae): the ecology of migration and likely climate change implications. Environ. Entomol. 36:1365–73 [Google Scholar]
  11. Beall G. 11.  1948. The fat content of a butterfly, Danaus plexippus Linn., as affected by migration. Ecology 29:80–94 [Google Scholar]
  12. Benbrook CM. 12.  2016. Trends in glyphosate herbicide use in the United States and globally. Environ. Sci. Europe 28:3 [Google Scholar]
  13. Berenbaum M. 13.  2015. Road worrier. Am. Entomol. 61:5–8 [Google Scholar]
  14. Bolsinger M, Lier ME, Hughes PR. 14.  1992. Influence of ozone air pollution on plant-herbivore interactions. Part 2: Effects of ozone on feeding preference, growth and consumption rates of monarch butterflies (Danaus plexippus). Environ. Pollut. 77:31–37 [Google Scholar]
  15. Bolsinger M, Lier ME, Lansky DM, Hughes PR. 15.  1991. Influence of ozone air pollution on plant-herbivore interactions. Part 1: Biochemical changes in ornamental milkweed (Asclepias curassavica L., Asclepiadaceae) induced by ozone. Environ. Pollut. 72:69–83 [Google Scholar]
  16. Boppré M. 16.  1993. The American monarch: courtship and chemical communication of a peculiar danaine butterfly. See Ref. 100 29–41
  17. Brower LP. 17.  1986. Commentary: the potential impact of Dipel spraying on the monarch butterfly overwintering phenomenon. Atala 14:17–19 [Google Scholar]
  18. Brower LP. 18.  1995. Understanding and misunderstanding the migration of the monarch butterfly (Nymphalidae) in North America: 1857-1995. J. Lepidopt. Soc. 49:4304–85 [Google Scholar]
  19. Brower LP. 19.  1999. Biological necessities for monarch butterfly overwintering in relation to the Oyamel forest ecosystem in Mexico. The 1997 North American Conference on the Monarch Butterfly J Hoth, L Merino, K Oberhauser, I Pisanty, S Price, T Wilkinson 11–29 Montréal: Commission Environ. Coop [Google Scholar]
  20. Brower LP. 20.  2001. Canary in the corn field: the monarch and the Bt corn controversy. Orion 20:32–41 [Google Scholar]
  21. Brower LP, Calvert WH. 21.  1985. Foraging dynamics of bird predators on overwintering monarch butterflies in Mexico. Evolution 39:852–68 [Google Scholar]
  22. Brower LP, Fink LS, Kiphart RJ, Pocius V, Zubieta RR, Ramírez MI. 22.  2015. Effect of the 2010–2011 drought on the lipid content of monarchs migrating through Texas to overwintering sites in Mexico. See Ref. 112 117–29
  23. Brower LP, Fink LS, Van Zandt Brower A, Leong K, Oberhauser K. 23.  et al. 1995. Roundtable: on the dangers of interpopulational transfers of monarch butterflies. BioScience 45:540–44 [Google Scholar]
  24. Brower LP, Fink LS, Walford P. 24.  2006. Fueling the fall migration of the monarch butterfly. Integr. Comp. Biol. 46:1123–42 [Google Scholar]
  25. Brower LP, Kust DR, Rendón-Salinas E, García-Serrano EG, Kust KR. 25.  et al. 2004. Catastrophic winter storm mortality of monarch butterflies in Mexico during January 2002. See Ref. 116 151–66
  26. Brower LP, Malcolm SB. 26.  1991. Animal migrations: endangered phenomena. Am. Zool. 31:265–76 [Google Scholar]
  27. Brower LP, Pyle RM. 27.  2004. The interchange of migratory monarchs between Mexico and the western United States, and the importance of floral corridors to the fall and spring migrations. Conservation of Migratory Pollinators and Their Nectar Corridors in North America GP Nabhan 144–166 Tucson: Arizona-Sonora Desert Museum [Google Scholar]
  28. Brower LP, Taylor OR, Williams EH, Slayback DA, Zubieta RR, Ramirez MI. 28.  2012. Decline of monarch butterflies overwintering in Mexico: Is the migratory phenomenon at risk?. Insect Conserv. Divers. 5:95–100 [Google Scholar]
  29. Brower LP, Williams EH, Slayback DA, Fink LS, Ramírez MI. 29.  et al. 2009. Oyamel fir forest trunks provide thermal advantages for overwintering monarch butterflies in Mexico. Insect Conserv. Divers. 2:163–75 [Google Scholar]
  30. Brown JJ, Chippendale GM. 30.  1974. Migration of the monarch butterfly, Danaus plexippus: energy sources. J. Insect Physiol. 20:1117–30 [Google Scholar]
  31. Burkle LA, Martin JC, Knight TM. 31.  2013. Plant-pollinator interactions over 120 years: loss of species, co-occurrence, and function. Science 339:1611–15 [Google Scholar]
  32. Calvert WH. 32.  1999. Patterns in the spatial and temporal use of Texas milkweeds (Asclepiadaceae) by the monarch butterfly (Danaus plexippus L.) during fall, 1996.. J. Lepidopt. Soc. 55:162–68 [Google Scholar]
  33. Calvert WH. 33.  2004. The effects of fire ants on monarch breeding in Texas. See Ref. 116 47–53
  34. Calvert WH. 34.  2004. Two methods for estimating overwintering monarch population size in Mexico. See Ref. 116 121–27
  35. Calvert WH, Brower LP. 35.  1981. The importance of forest cover for the survival of overwintering monarch butterflies (Danaus plexippus, Danaidae). J. Lepidopt. Soc. 35:216–25 [Google Scholar]
  36. Calvert WH, Hedrick LE, Brower LP. 36.  1979. Mortality of the monarch butterfly (Danaus plexippus L.): avian predation at five overwintering sites in Mexico. Science 204:847–51 [Google Scholar]
  37. Calvert WH, Zuchowski W, Brower LP. 37.  1983. The effect of rain, snow and freezing temperatures on overwintering monarch butterflies in Mexico. Biotropica 15:42–47 [Google Scholar]
  38. Casagrande RA, Dacey JE. 38.  2007. Monarch butterfly oviposition on swallow-worts (Vincetoxicum spp.). Environ. Entomol. 36:631–36 [Google Scholar]
  39. Chaplin S, Wells P. 39.  1982. Energy reserves and metabolic expenditure of monarch butterflies overwintering in Southern California. Ecol. Entomol. 7:249–56 [Google Scholar]
  40. Chapman BB, Brönmark C, Nilsson , Hansson LA. 40.  2011. The ecology and evolution of partial migration. Oikos 120:121764–1775 [Google Scholar]
  41. Chappelka A, Renfro J, Somers G, Nash B. 41.  1997. Evaluation of ozone injury on foliage of black cherry (Prunus serotina) and tall milkweed (Asclepias exaltata) in Great Smoky Mountains National Park. Environ. Pollut. 95:13–18 [Google Scholar]
  42. Cockrell BJ, Malcolm SB, Brower LP. 42.  1993. Time, temperature, and latitudinal constraints on the annual recolonization of eastern North America by the monarch butterfly. See Ref. 100 233–51
  43. Couture JJ, Serbin SP, Townsend PA. 43.  2015. Elevated temperature and periodic water stress alter growth and quality of common milkweed (Asclepias syriaca) and monarch (Danaus plexippus) larval performance. Arthropod-Plant Interact 9:149–61 [Google Scholar]
  44. Davis AK. 44.  2012. Are migratory monarchs really declining in eastern North America? Examining evidence from two fall census programs. Insect Conserv. Divers. 8:101–5 [Google Scholar]
  45. Davis AK, Dyer LA. 45.  2015. Long-term trends in eastern North American monarch butterflies: a collection of studies focusing on spring, summer, and fall dynamics. Ann. Entomol. Soc. Am. 108:661–63 [Google Scholar]
  46. De Roode JC, Pedersen AB, Hunter MD, Altizer S. 46.  2008. Host plant species affects virulence in monarch butterfly parasites. J. Anim. Ecol. 77:120–26 [Google Scholar]
  47. Denevan WM. 47.  1992. The pristine myth: the landscape of the Americas in 1492. Ann. Assoc. Am. Geogr. 82:369–85 [Google Scholar]
  48. Dingle H, Zalucki MP, Rochester WA, Armijo-Prewitt T. 48.  2005. Distribution of the monarch butterfly, Danaus plexippus (L.) (Lepidoptera: Nymphalidae), in western North America. Biol. J. Linn. Soc. 85:491–500 [Google Scholar]
  49. DiTommaso A, Losey JE. 49.  2003. Oviposition preference and larval performance of monarch butterflies (Danaus plexippus) on two invasive swallow-wort species. Entomol. Exp. Appl. 108:205–9 [Google Scholar]
  50. Dively GP, Rose R, Sears MK, Hellmich RL, Stanley-Horn DE. 50.  et al. 2004. Effects on monarch butterfly larvae (Lepidoptera: Danaidae) after continuous exposure to Cry1Ab-expressing corn during anthesis. Environ. Entomol. 33:1116–25 [Google Scholar]
  51. Dockx C, Brower LP, Wassenaar LI, Hobson KA. 51.  2004. Do North American monarch butterflies travel to Cuba? Stable isotope and chemical tracer techniques. Ecol. Appl. 14:1106–14 [Google Scholar]
  52. Dyer LA, Forister ML. 52.  2016. Wherefore and whither the modeler: understanding the population dynamics of monarchs will require integrative and quantitative techniques. Ann. Entomol. Soc. Am. 109:172–75 [Google Scholar]
  53. Erickson JM. 53.  1973. The utilization of various Asclepias species by larvae of the monarch butterfly Danaus plexippus. Psyche 80:230–44 [Google Scholar]
  54. Espeset AE, Harrison JG, Shapiro AM, Nice CC, Thorne JH. 54.  et al. 2016. Understanding a migratory species in a changing world: climatic effects and demographic declines in the western monarch revealed by four decades of intensive monitoring. Oecologia 181:819–30 [Google Scholar]
  55. Fernández-Haeger J, Jordano D, Zalucki MP. 55.  2015. Monarchs across the Atlantic Ocean. See Ref. 112 247–56
  56. Fink LS, Brower LP. 56.  1981. Birds can overcome the cardenolide defence of monarch butterflies in Mexico. Nature 291:67–70 [Google Scholar]
  57. Fishbein M, Chuba D, Ellison C, Mason-Gamer RJ, Lynch SP. 57.  2011. Phylogenetic relationships of Asclepias (Apocynaceae) inferred from non-coding chloroplast DNA sequences. Syst. Bot. 36:1008–23 [Google Scholar]
  58. Flockhart DTT, Brower LP, Ramirez MI, Hobson KA, Wassenaar LI. 58.  et al. 2017. Regional climate on the breeding grounds predicts variation in the natal origin of monarch butterflies overwintering in Mexico over 38 years. Glob. Change Biol. 23:72565–76 [Google Scholar]
  59. Flockhart DTT, Pichancourt JB, Norris DR, Martin TG. 59.  2015. Unravelling the annual cycle in a migratory animal: Breeding-season habitat loss drives declines of monarch butterflies. J. Anim. Ecol. 84:155–65 [Google Scholar]
  60. Flockhart DTT, Wassenaar LI, Hobson KA, Martin TG, Wunder MB, Norris DR. 60.  2013. Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America. Proc. R. Soc. B 280:176820131087 [Google Scholar]
  61. Frey D, Schaffner A. 61.  2004. Spatial and temporal pattern of monarch overwintering abundance in western North America. See Ref. 116 167–76
  62. Gaertner EE. 62.  1979. The history and use of milkweed (Asclepias syriaca L.). Econ. Bot. 33:119–23 [Google Scholar]
  63. García ER, Equihau-Zamora ME. 63.  1997. New records of plant species used by adult monarch butterflies Danaus plexippus L. (Lepidoptera: Nymphalidae: Danainae) during migration in Mexico. Can. Entomol. 129:375–76 [Google Scholar]
  64. Gibo DL, McCurdy JA. 64.  1993. Lipid accumulation by migrating monarch butterflies (Danaus plexippus L.). Can. J. Zool. 71:76–82 [Google Scholar]
  65. Glendinning JI, Alonso Mejía A, Brower LP. 65.  1988. Behavioral and ecological interactions of foraging mice (Peromyscus melanotis) with overwintering monarch butterflies (Danaus plexippus) in México. Oecologia 75:222–27 [Google Scholar]
  66. Glendinning JI, Brower LP, Montgomery CA. 66.  1990. Responses of three mouse species to deterrent chemicals in the monarch butterfly. I. Taste and toxicity tests using artificial diets laced with digitoxin or monocrotaline. Chemoecology 1:3114–23 [Google Scholar]
  67. Goehring L, Oberhauser KS. 67.  2002. Effects of photoperiod, temperature, and host plant age on induction of reproductive diapause and development time in Danaus plexippus. Ecol. Entomol. 27:674–85 [Google Scholar]
  68. Goulson D. 68.  2013. An overview of the environmental risks posed by neonicotinoid insecticides. J. Appl. Ecol. 50:977–87 [Google Scholar]
  69. Griffiths J, Villablanca F. 69.  2015. Managing monarch butterfly overwintering groves: making room among the eucalyptus. Calif. Fish Game 101:40–50 [Google Scholar]
  70. Guerra PA, Gegear RJ, Reppert SM. 70.  2014. A magnetic compass aids monarch butterfly migration. Nat. Commun. 5:4164 [Google Scholar]
  71. Guerra PA, Reppert SM. 71.  2013. Coldness triggers northward flight in remigrant monarch butterflies. Curr. Biol. 23:419–23 [Google Scholar]
  72. Gustafsson KM, Agrawal AA, Lewenstein BV, Wolf SA. 72.  2015. The monarch butterfly through time and space: the social construction of an icon. BioScience 65:612–22 [Google Scholar]
  73. Haan NL, Hunter MR, Hunter MD. 73.  2012. Investigating predictors of plant establishment during roadside restoration. Restor. Ecol. 20:315–21 [Google Scholar]
  74. Hartzler RG. 74.  2010. Reduction in common milkweed (Asclepias syriaca) occurrence in Iowa cropland from 1999 to 2009. Crop Prot 29:1542–44 [Google Scholar]
  75. Heap I. 75.  2017. International Survey of Herbicide Resistant Weeds. Accessed March 9, 2017. http://www.weedscience.com/
  76. Hellmich RL, Siegfried B, Sears MK, Stanley-Horn DE, Mattila HR. 76.  et al. 2001. Monarch larvae sensitivity to Bacillus thuringiensis-purified proteins and pollen. PNAS 98:11925–30 [Google Scholar]
  77. Herman WS. 77.  1981. Studies on the adult reproductive diapause of the monarch butterfly, Danaus plexippus. Biol. Bull. 160:89–106 [Google Scholar]
  78. Honey-Rosés J. 78.  2009. Disentangling the proximate factors of deforestation: the case of the monarch butterfly biosphere reserve in Mexico. Land Degrad. Dev. 20:22–32 [Google Scholar]
  79. Honey-Rosés J, Baylis K, Ramírez MI. 79.  2011. A spatially explicit estimate of avoided forest loss. Conserv. Biol. 25:1032–43 [Google Scholar]
  80. Honey-Rosés J, López-Garcia J, Rendón-Salinas E, Peralta-Higuera A, Galindo-Leal C. 80.  2009. To pay or not to pay? Monitoring performance and enforcing conditionality when paying for forest conservation in Mexico. Environ. Conserv. 36:120–28 [Google Scholar]
  81. Howard E, Aschen H, Davis AK. 81.  2010. Citizen science observations of monarch butterfly overwintering in the southern United States. Psyche 10:1–6 [Google Scholar]
  82. Inamine H, Ellner SP, Springer JP, Agrawal AA. 82.  2016. Linking the continental migratory cycle of the monarch butterfly to understand its population decline. Oikos 125:81081–91 [Google Scholar]
  83. Jepsen S, Black SH. 83.  2015. Understanding and conserving the western North American monarch population. See Ref. 112 147–56
  84. Jesse LCH, Obrycki JJ. 84.  2000. Field deposition of Bt transgenic corn pollen: lethal effects on the monarch butterfly. Oecologia 125:241–48 [Google Scholar]
  85. Kelley RB, Seiber JN, Jones AD, Segall HJ, Brower LP. 85.  1987. Pyrrolizidine alkaloids in overwintering monarch butterflies (Danaus plexippus) from Mexico. Experientia 43:8943–46 [Google Scholar]
  86. Knight A, Brower LP. 86.  2009. The influence of eastern North American autumnal migrant monarch butterflies (Danaus plexippus L.) on continuously breeding resident monarch populations in southern Florida. J. Chem. Ecol. 35:816–23 [Google Scholar]
  87. Koch RL, Venette RC, Hutchison WD. 87.  2006. Predicted impact of an exotic generalist predator on monarch butterfly (Lepidoptera: Nymphalidae) populations: a quantitative risk assessment. Biol. Invasions 8:1179–93 [Google Scholar]
  88. Krischik V, Rogers M, Gupta G, Varshney A. 88.  2015. Soil-applied imidacloprid translocates to ornamental flowers and reduces survival of adult Coleomegilla maculata, Harmoniaaxyridis, and Hippodamia convergens lady beetles, and larval Danaus plexippus and Vanessa cardui butterflies. PLOS ONE 10:e0119133 [Google Scholar]
  89. Ladner D, Altizer S. 89.  2005. Oviposition preference and larval performance of North American monarch butterflies on four Asclepias species. Entomol. Exp. Appl. 116:9–20 [Google Scholar]
  90. Lal R, Reicosky DC, Hanson JD. 90.  2007. Evolution of the plow over 10,000 years and the rationale for no-till farming. Soil Tillage Res 93:1–12 [Google Scholar]
  91. Lemoine NP. 91.  2015. Climate change may alter breeding ground distributions of eastern migratory monarchs (Danaus plexippus) via range expansion of Asclepias host plants. PLOS ONE 10:e0118614 [Google Scholar]
  92. Leong KLH. 92.  1990. Microenvironmental factors associated with the winter habitat of the monarch butterfly (Lepidoptera: Danaidae) in central California. Ann. Entomol. Soc. Am. 83:906–10 [Google Scholar]
  93. Leong KLH, Frey D, Brenner G. 93.  1991. Use of multivariate analyses to characterize the monarch butterfly (Lepidoptera: Danaidae) winter habitat. Ann. Entomol. Soc. Am. 84:263–67 [Google Scholar]
  94. Leong KLH, Sakai WH, Bremer W, Feuerstein D, Yoshimura G. 94.  2004. Analysis of the pattern of distribution and abundance of monarch overwintering sites along the California coastline. See Ref. 116 177–85
  95. Losey JE, Rayor LS, Carter ME. 95.  1999. Transgenic pollen harms monarch larvae. Nature 399:214 [Google Scholar]
  96. Malcolm SB, Brower LP. 96.  1986. Selective oviposition by monarch butterflies (Danaus plexippus L.) in a mixed stand of Asclepias curassavica L. and A. incarnata L. in south Florida. J. Lepidopt. Soc. 40:255–63 [Google Scholar]
  97. Malcolm SB, Cockrell BJ, Brower LP. 97.  1987. Monarch butterfly voltinism: effects of temperature constraints at different latitudes. Oikos 49:77–82 [Google Scholar]
  98. Malcolm SB, Cockrell BJ, Brower LP. 98.  1989. The cardenolide fingerprint of monarch butterflies reared on the common milkweed, Asclepias syriaca L. J. Chem. Ecol. 15:819–53 [Google Scholar]
  99. Malcolm SB, Cockrell BJ, Brower LP. 99.  1993. Spring recolonization of eastern North America by the monarch butterfly: successive brood or single sweep migration?. See Ref. 100 253–67
  100. Malcolm SB, Zalucki MP. 100.  eds 1993. Biology and Conservation of the Monarch Butterfly Los Angeles: Nat. Hist. Mus. Los Angeles County
  101. Masters AR, Malcolm SB, Brower LP. 101.  1988. Monarch butterfly (Danaus plexippus) thermoregulatory behavior and adaptations for overwintering in Mexico. Ecology 69:458–67 [Google Scholar]
  102. McKenna DD, McKenna KM, Malcolm SB, Berenbaum MR. 102.  2001. Mortality of Lepidoptera along roadways in central Illinois. J. Lepidopt. Soc. 55:63–68 [Google Scholar]
  103. Menge EO, Greenfield ML, McConchie CA, Bellairs SM, Lawes MJ. 103.  2017. Density‐dependent reproduction and pollen limitation in an invasive milkweed, Calotropisprocera (Ait.) R. Br.(Apocynaceae). Aust. Ecol. 42:61–71 [Google Scholar]
  104. Mooney KA, Halitschke R, Kessler A, Agrawal AA. 104.  2010. Evolutionary trade-offs in plants mediate the strength of trophic cascades. Science 327:1642–44 [Google Scholar]
  105. Nagano CD, Sakai WH, Malcolm SB, Cockrell BJ, Donahue JP, Brower LP. 105.  1993. Spring migration of monarch butterflies in California. See Ref. 100 219–32
  106. Nail KR, Batalden RV, Oberhauser KS. 106.  2015. What's too hot and what's too cold?. See Ref. 112 99–108
  107. New TR. 107.  2008. Are butterfly releases at weddings a conservation concern or opportunity?. J. Insect Conserv. 12:93–95 [Google Scholar]
  108. Nordby D, Hartzler B, Bradley K. 108.  2007. Biology and Management of Waterhemp The Glyphosate, Weeds, and Crop Series, GWC-13 West Lafayette, IN: Purdue Univ. Ext.
  109. Oberhauser K, Wiederholt R, Diffendorfer JE, Semmens D, Ries L. 109.  et al. 2017. A trans‐national monarch butterfly population model and implications for regional conservation priorities. Ecol. Entomol. 42:51–60 [Google Scholar]
  110. Oberhauser KS, Anderson M, Anderson S, Caldwell W, De Anda A. 110.  et al. 2015. Lacewings, wasps, and flies—oh my: insect enemies take a bite out of monarchs. See Ref. 112 71–82
  111. Oberhauser KS, Brinda SJ, Weaver S, Moon RD, Manweiler SA, Read N. 111.  2006. Growth and survival of monarch butterflies (Lepidoptera: Danaidae) after exposure to permethrin barrier treatments. Environ. Entomol. 35:1626–34 [Google Scholar]
  112. Oberhauser KS, Nail KR, Altizer S. 112.  eds 2015. Monarchs in a Changing World: Biology and Conservation of an Iconic Insect Ithaca, NY: Cornell Univ. Press
  113. Oberhauser KS, Prysby M, Mattila HR, Stanley-Horn DE, Sears MK. 113.  et al. 2001. Temporal and spatial overlap between monarch larvae and corn pollen. PNAS 98:11913–18 [Google Scholar]
  114. Oberhauser KS, Ries L, Altizer S, Batalden RV, Kudell-Ekstrum J. 114.  et al. 2015. Contributions to monarch biology and conservation through citizen science. See Ref. 112 13–30
  115. Oberhauser KS, Rivers ERL. 115.  2003. Monarch butterfly (Danaus plexippus) larvae and Bt maize pollen: a review of ecological risk assessment for a non-target species. AgBiotechNet 5:1–7 [Google Scholar]
  116. Oberhauser KS, Solensky MJ. 116.  eds 2004. The Monarch Butterfly: Biology and Conservation Ithaca, NY: Cornell Univ. Press
  117. Pecenka JR, Lundgren JG. 117.  2015. Non-target effects of clothianidin on monarch butterflies. Sci. Nat. 102:3–41–4 [Google Scholar]
  118. Pelton E, Jepsen S, Schultz C, Fallon C, Black SH. 118.  2016. State of The Monarch Butterfly Overwintering Sites in California Portland, OR: Xerces Soc. Invertebr. Conserv.
  119. 119. Pew Initiative. 2003. Three Years Later: Genetically Engineered Corn and the Monarch Butterfly Controversy Washington, DC: Pew Initiat. Food Biotechnol.
  120. Pierce AA, Zalucki MP, Bangura M, Udawatta M, Kronforst MR. 120.  et al. 2014. Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies. Proc. R. Soc. B 281:20142230 [Google Scholar]
  121. Pleasants JM. 121.  2015. Monarch butterflies and agriculture. See Ref. 112 169–78
  122. Pleasants JM, Hellmich RL, Dively GP, Sears MK, Stanley-Horn DE. 122.  et al. 2001. Corn pollen deposition on milkweeds in or near cornfields. PNAS 98:11919–24 [Google Scholar]
  123. Pleasants JM, Oberhauser KS. 123.  2013. Milkweed loss in agricultural fields because of herbicide use: effect on the monarch butterfly population. Insect Conserv. Divers. 6:135–44 [Google Scholar]
  124. Pleasants JM, Williams EH, Brower LP, Oberhauser KS, Taylor OR. 124.  2016. Conclusion of no decline in summer monarch population not supported. Ann. Entomol. Soc. Am. 109:169–71 [Google Scholar]
  125. Pleasants JM, Zalucki MP, Oberhauser KS, Brower LP, Taylor OR, Thogmartin WE. 125.  2017. Interpreting surveys to estimate the size of the monarch butterfly population: pitfalls and prospects. PLOS ONE 12:7e0181245 [Google Scholar]
  126. 126. Pollinator Health Task Force. 2015. National Strategy to Promote the Health of Honey Bees and Other Pollinators Washington, DC: The White House
  127. Rafter JL, Agrawal AA, Preisser EL. 127.  2013. Chinese mantids gut toxic monarch caterpillars: avoidance of prey defense?. Ecol. Entomol. 38:76–78 [Google Scholar]
  128. Ramírez MI, Sáenz-Romero C, Rehfeldt G, Salas-Canela L. 128.  2015. Threats to the availability of overwintering habitat in the monarch butterfly biosphere reserve: land use and climate change. See Ref. 112 157–68
  129. Rasmann S, Pellissier L. 129.  2015. Adaptive responses of plants to insect herbivores under climate change. Climate Change and Insect Pests C Björkman, P Niemalä 38–53 Wallingford, UK: CAB Int. [Google Scholar]
  130. Rawlings JE, Lederhouse RC. 130.  1981. Developmental influences of thermal behavior on monarch caterpillars (Danaus plexippus): an adaptation for migration (Lepidoptera: Nymphalidae: Danainae). J. Kans. Entomol. Soc. 54:378–408 [Google Scholar]
  131. Rayor LS. 131.  2004. Effects of monarch larval host plant chemistry and body size on Polistes wasp predation. See Ref. 116 39–46
  132. Rehfeldt GE, Crookston NL, Sáenz-Romero C, Campbell EM. 132.  2012. North American vegetation model for land‐use planning in a changing climate: a solution to large classification problems. Ecol. Appl. 22:119–41 [Google Scholar]
  133. Rendón-Salinas E, Martínez-Meza F, Cruz-Piña M, Fajardo-Arroyo A. 133.  2017. Superficie forestal ocupada por las colonias de hibernación de la mariposa monarca en México en la temporada 2016–2017 WWF-México, DF. https://www.learner.org/jnorth/tm/monarch/Pop_WWFMonitoreo2016_2017.pdf
  134. Ries L, Taron DJ, Rendón-Salinas E. 134.  2015. The disconnect between summer and winter monarch trends for the eastern migratory population: possible links to different drivers. Ann. Entomol. Soc. Am. 108:691–99 [Google Scholar]
  135. Riley CV, Bush AE. 135.  1882. The butterfly trees of Monterey again. Am. Nat. 16:64 [Google Scholar]
  136. Rudolph DC, Ely CA, Schaefer RR, Williamson JH, Thill RE. 136.  2006. Monarch (Danaus plexippus L. Nymphalidae) migration, nectar resources and fire regimes in the Ouachita Mountains of Arkansas. J. Lepidopt. Soc. 60:165–70 [Google Scholar]
  137. Sáenz-Romero C, Rehfeldt GE, Duval P, Lindig-Cisneros RA. 137.  2012. Abies religiosa habitat prediction in climatic change scenarios and implications for monarch butterfly conservation in Mexico. Forest Ecol. Manag. 275:98–106 [Google Scholar]
  138. Satterfield DA, Maerz JC, Altizer S. 138.  2015. Loss of migratory behavior increases infection risk for a butterfly host. Proc. R. Soc. B 282:20141734 [Google Scholar]
  139. Satterfield DA, Villablanca FX, Maerz JC, Altizer S. 139.  2016. Migratory monarchs wintering in California experience low infection risk compared to monarchs breeding year-round on non-native milkweed. Integr. Comp. Biol. 56:2343–52 [Google Scholar]
  140. Satterfield DA, Wright A, Altizer S. 140.  2013. Lipid reserves trade off against immune defense in healthy and diseased migrating monarchs (Danaus plexippus). Curr. Zool. 59:393–402 [Google Scholar]
  141. Saunders SP, Ries L, Oberhauser KS, Thogmartin WE, Zipkin EF. 141.  2017. Local and cross-seasonal associations of climate and land use with abundance of monarch butterflies (Danaus plexippus). Ecography 40:1–12 [Google Scholar]
  142. Schroeder LA. 142.  1976. Energy, matter and nitrogen utilization by the larvae of the monarch butterfly Danaus plexippus. Oikos 27:259–64 [Google Scholar]
  143. Scriber JM. 143.  2001. Bt or not Bt: Is that the question?. PNAS 98:12328–30 [Google Scholar]
  144. Sears MK, Hellmich RL, Siegfried BD, Pleasants JM, Stanley-Horn DE. 144.  et al. 2001. Impact of Bt corn pollen on monarch butterfly populations: a risk assessment. PNAS 98:11937–42 [Google Scholar]
  145. Semmens BX, Semmens DJ, Thogmartin WE, Wiederholt R, López-Hoffman L. 145.  et al. 2016. Quasi-extinction risk and population targets for the eastern, migratory population of monarch butterflies (Danaus plexippus). Sci. Rep. 6:23265 [Google Scholar]
  146. Serratore VR, Zalucki MP, Carter PA. 146.  2013. Thermoregulation in moulting and feeding Danaus plexippus L. (Lepidoptera: Nymphalidae) caterpillars. Aust. J. Entomol. 52:8–13 [Google Scholar]
  147. Snell-Rood EC, Espeset A, Boser CJ, White WA, Smykalski R. 147.  2014. Anthropogenic changes in sodium affect neural and muscle development in butterflies. PNAS 111:10221–26 [Google Scholar]
  148. Snook LC. 148.  1993. Conservation of the monarch butterfly reserves in Mexico: focus on the forest. See Ref. 100 363–75
  149. Stanley-Horn DE, Dively GP, Hellmich RL, Mattila HR, Sears MK. 149.  et al. 2001. Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies. PNAS 98:11931–36 [Google Scholar]
  150. Stelljes ME, Seiber JN. 150.  1990. Pyrrolizidine alkaloids in an overwintering population of monarch butterflies (Danaus plexippus) in California. J. Chem. Ecol. 16:51459–70 [Google Scholar]
  151. Stenoien C, Nail KR, Zalucki JM, Parry H, Oberhauser KS, Zalucki MP. 151.  2016. Monarchs in decline: a collateral landscape‐level effect of modern agriculture. Insect Sci https://doi.org/10.1111/1744-7917.12404 [Crossref]
  152. Sternberg ED, Lefèvre T, Li J, de Castillejo CL, Li H. 152.  et al. 2012. Food plant-derived disease tolerance and resistance in a natural butterfly-plant-parasite interaction. Evolution 66:3367–76 [Google Scholar]
  153. Stevens SR, Frey DF. 153.  2010. Host plant pattern and variation in climate predict the location of natal grounds for migratory monarch butterflies in western North America. J. Insect Conserv. 14:731–44 [Google Scholar]
  154. Stimson J, Berman M. 154.  1990. Predator induced colour polymorphism in Danaus plexippus L. (Lepidoptera: Nymphalidae) in Hawaii. Heredity 65:401–6 [Google Scholar]
  155. Stimson J, Kasuya M. 155.  2000. Decline in the frequency of the white morph of the monarch butterfly (Danaus plexippus L. Nymphalidae) on Oahu, Hawaii. J. Lepidopt. Soc. 54:29–32 [Google Scholar]
  156. Tao L, Ahmad A, de Roode JC, Hunter MD. 156.  2016. Arbuscular mycorrhizal fungi affect plant tolerance and chemical defences to herbivory through different mechanisms. J. Ecol. 104:561–71 [Google Scholar]
  157. Tao L, Berns AR, Hunter MD. 157.  2014. Why does a good thing become too much? Interactions between foliar nutrients and toxins determine performance of an insect herbivore. Funct. Ecol. 28:190–96 [Google Scholar]
  158. Tao L, Hunter MD. 158.  2012. Does anthropogenic nitrogen deposition induce phosphorus limitation in herbivorous insects?. Glob. Change Biol. 18:1843–53 [Google Scholar]
  159. Tao L, Hunter MD. 159.  2015. Effects of soil nutrients on the sequestration of plant defence chemicals by the specialist insect herbivore, Danaus plexippus. Ecol. Entomol. 40:123–32 [Google Scholar]
  160. Thogmartin WE, Diffendorfer JE, López-Hoffman L, Oberhauser K, Pleasants J. 160.  et al. 2017. Density estimates of monarch butterflies overwintering in central Mexico. PeerJ 5:e3221 [Google Scholar]
  161. Tollenaar M, Fridgen J, Tyagi P, Stackhouse PW Jr., Kumudini S. 161.  2017. The contribution of solar brightening to the US maize yield trend. Nat. Climate Change 7:275–78 [Google Scholar]
  162. Tuskes PM, Brower LP. 162.  1978. Overwintering ecology of the monarch butterfly, Danaus plexippus L., in California. Ecol. Entomol. 3:141–53 [Google Scholar]
  163. 163. UNESCO. 2017. World network of Biosphere Reserves 2016–2017. United Nations Educational, Scientific and Cultural Organization, Man and the Biosphere Programme. http://unesdoc.unesco.org/images/0024/002449/244977M.pdf
  164. Urquhart FA. 164.  1960. The Monarch Butterfly Toronto: Univ. Toronto Press
  165. Urquhart FA. 165.  1976. Found at last: the monarch's winter home. National Geographic Magazine Aug 150:2160–73 [Google Scholar]
  166. Urquhart FA. 166.  1987. The Monarch Butterfly: International Traveler Chicago: Nelson-Hall
  167. Vane-Wright RI. 167.  1993. The Columbus hypothesis: an explanation for the dramatic 19th century range expansion of the monarch butterfly. See Ref. 100 179–87
  168. Vannette RL, Hunter MD. 168.  2011. Genetic variation in expression of defense phenotype may mediate evolutionary adaptation of Asclepias syriaca to elevated CO2. Glob. Change Biol. 17:1277–88 [Google Scholar]
  169. Vidal O, Lopez-García J, Rendón-Salinas E. 169.  2014. Trends in deforestation and forest degradation after a decade of monitoring in the Monarch Butterfly Biosphere Reserve in Mexico. Conserv. Biol. 28:177–86 [Google Scholar]
  170. Wassenaar LI, Hobson KA. 170.  1998. Natal origins of migratory monarch butterflies at wintering colonies in Mexico: new isotopic evidence. PNAS 95:15436–39 [Google Scholar]
  171. Wenner AM, Harris AM. 171.  1993. Do California monarchs undergo long-distance directed migration?. See Ref. 100 209–18
  172. Williams EH, Brower LP. 172.  2015. Microclimatic protection of overwintering monarchs provided by Mexico's high-elevation oyamel fir forests: a review. See Ref. 112 109–16
  173. Williams EH, Brower LP. 173.  2016. A conservation concern: How many monarchs are there?. News Lepidopt. Soc. 58:90–93 [Google Scholar]
  174. Woodson RE. 174.  1954. The North American species of Asclepias L. Ann. Mo. Bot. Gard. 41:1–211 [Google Scholar]
  175. Yang LH, Ostrovsky D, Rogers MC, Welker JM. 175.  2016. Intra-population variation in the natal origins and wing morphology of overwintering western monarch butterflies Danaus plexippus. Ecography 39:998–1007 [Google Scholar]
  176. Zalucki MP. 176.  1981. The effects of age and weather on egg laying in Danaus plexippus L. (Lepidoptera: Danaidae). Res. Popul. Ecol. 23:318–27 [Google Scholar]
  177. Zalucki MP. 177.  1982. Temperature and rate of development in Danaus plexippus L. and D. chrysippus L. (Lepidoptera: Nymphalidae). J. Aust. Entomol. Soc. 21:241–46 [Google Scholar]
  178. Zalucki MP, Brower LP, Malcolm SB, Slager BH. 178.  2015. Estimating the climate signal in monarch population decline: no direct evidence for an impact of climate change?. See Ref. 112 130–41
  179. Zalucki MP, Clarke AR, Malcolm SB. 179.  2002. Ecology and behavior of first instar larval Lepidoptera. Annu. Rev. Entomol. 47:361–93 [Google Scholar]
  180. Zalucki MP, Lammers JH. 180.  2010. Dispersal and egg shortfall in monarch butterflies: What happens when the matrix is cleaned up?. Ecol. Entomol. 35:84–91 [Google Scholar]
  181. Zalucki MP, Malcolm SB, Hanlon CC, Paine TD. 181.  2012. First-instar monarch larval growth and survival on milkweeds in Southern California: effects of latex, leaf hairs and cardenolides. Chemoecology 22:75–88 [Google Scholar]
  182. Zalucki MP, Malcolm SB, Paine TD, Hanlon CC, Brower LP, Clarke AR. 182.  2001. It's the first bites that count: survival of first-instar monarchs on milkweeds. Austral Ecol 26:547–55 [Google Scholar]
  183. Zalucki MP, Parry HR, Zalucki JM. 183.  2016. Movement and egg laying in monarchs: To move or not move, that is the equation. Austral Ecol 41:154–67 [Google Scholar]
  184. Zalucki MP, Rochester WA. 184.  1999. Estimating the effect of climate on the distribution and abundance of the monarch butterfly, Danaus plexippus L.: a tale of two continents. The 1997 North American Conference on the Monarch Butterfly J Hoth, L Merino, K Oberhauser, I Pisanty, S Price, T. Wilkinson 150–63 Montréal: Commission Environ. Coop. [Google Scholar]
  185. Zalucki MP, Rochester WA. 185.  2004. Spatial and temporal population dynamics of monarchs down-under: lessons for North America. See Ref. 116 219–28
  186. Zangerl AR, McKenna D, Wraight CL, Carroll M, Ficarello P. 186.  et al. 2001. Effects of exposure to event 176 Bacillus thuringiensis corn pollen on monarch and black swallowtail caterpillars under field conditions. PNAS 98:11908–12 [Google Scholar]
  187. Zipkin EF, Ries L, Reeves R, Regetz J, Oberhauser KS. 187.  2012. Tracking climate impacts on the migratory monarch butterfly. Glob. Change Biol. 18:3039–49 [Google Scholar]

Data & Media loading...

  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error