Prevalence of monarch (Danaus plexippus) and queen (Danaus gilippus) butterflies in West Texas during the fall of 2018
Brym MZ, Henry C, Lukashow-Moore SP and others. BMC ecology, June 2020.
Read the paper Free to read · doi:10.1186/s12898-020-00301-x
What this paper is about
Milkweed restoration has concentrated on the Midwest. This survey counted monarchs and queens across west Texas through the autumn of 2018.
Texas is the corridor every eastern monarch passes through twice a year, and the study extends the habitat question to a region outside the usual focus.
Summarised here from the abstract below. Not the authors’ words.
Abstract
BackgroundThe monarch butterfly (Danaus plexippus) is a conspicuous insect that has experienced a drastic population decline over the past two decades. While there are several factors contributing to dwindling monarch populations, habitat loss is considered the most significant threat to monarchs. In the United States, loss of milkweed, particularly in the Midwest, has greatly reduced the available breeding habitat of monarchs. This has led to extensive efforts to conserve and restore milkweed resources throughout the Midwest. Recently, these research and conservation efforts have been expanded to include other important areas along the monarch's migratory path.ResultsDuring the fall of 2018, we conducted surveys of monarch eggs and larvae through West Texas. We documented monarch and queen butterfly (Danaus gilippus) reproduction throughout the region and used the proportion of monarch and queen larva to estimate the number of monarch eggs. Peak egg densities for monarchs were as high as 0.78 per milkweed ramet after correction for the presence of queens. Despite our observations encompassing only a limited sample across one season, the peak monarch egg densities we observed exceeded published reports from when monarch populations were higher.ConclusionsTo our knowledge, this is the first study to correct for the presence of queens when calculating the density of monarch eggs. This research also provides insight into monarch utilization of less well-known regions, such as West Texas, and highlights the need to expand the scope of monarch monitoring and conservation initiatives. While the importance of monarch research and conservation in the Midwest is unquestionable, more comprehensive efforts may identify new priorities in monarch conservation and lead to a more robust and effective overall strategy, particularly given the dynamic and rapidly changing global environment.
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Milkweed USA. (2026). Prevalence of monarch (Danaus plexippus) and queen (Danaus gilippus) butterflies in West Texas during the fall of 2018 (listing). Retrieved DATE, from https://milkweedusa.com/research/prevalence-of-monarch-danaus-plexippus-and-queen-danaus-gilippus-2020/
"Prevalence of monarch (Danaus plexippus) and queen (Danaus gilippus) butterflies in West Texas during the fall of 2018 (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/prevalence-of-monarch-danaus-plexippus-and-queen-danaus-gilippus-2020/. Accessed DATE.
Milkweed USA. "Prevalence of monarch (Danaus plexippus) and queen (Danaus gilippus) butterflies in West Texas during the fall of 2018 (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/prevalence-of-monarch-danaus-plexippus-and-queen-danaus-gilippus-2020/.
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title = {Prevalence of monarch (Danaus plexippus) and queen (Danaus gilippus) butterflies in West Texas during the fall of 2018 (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/prevalence-of-monarch-danaus-plexippus-and-queen-danaus-gilippus-2020/},
note = {Accessed DATE}
}