Editing Peppered moth (section)

== Ecology and life cycle ==
[[File:Biston betularia.png|thumb|left|''Biston betularia'' caterpillars on birch (left) and willow (right), demonstrating twig mimicry and effective [[countershading]].<ref>{{cite journal |vauthors=Noor MA, Parnell RS, Grant BS |editor1-last=Humphries |editor1-first=Stuart |title=A Reversible Color Polyphenism in American Peppered Moth (''Biston betularia cognataria'') Caterpillars |journal=PLOS ONE |volume=3 |issue=9 |pages=e3142 |year=2008 |pmid=18769543 |doi=10.1371/journal.pone.0003142 |pmc=2518955|bibcode=2008PLoSO...3.3142N |doi-access=free }}</ref>]]
In [[United Kingdom|Great Britain]] and [[Ireland]], the peppered moth is [[voltinism|univoltine]] (''i.e.'', it has one generation per year), whilst in south-eastern [[North America]] it is bivoltine (two generations per year). The [[lepidoptera]]n [[biological life cycle|life cycle]] consists of four stages: ova (eggs), several [[larva]]l [[instar]]s ([[caterpillar]]s), [[pupa]]e, which overwinter in the soil, and [[imago|imagines]] (adults). During the day, the moths typically rest on trees, where they are preyed on by birds.

The caterpillar is a twig [[Mimicry|mimic]], varying in colour between green and brown. On a historical note, it was one of the first animals to be identified as being [[camouflage]]d with [[countershading]] to make it appear flat (shading being the main visual cue that makes things appear solid), in a paper by [[Edward Bagnall Poulton]] in 1887.<ref>{{cite journal | title=Notes in 1886 upon Lepidopterous Larvae, etc. | author=Poulton, Edward B. | journal=Transactions of the Entomological Society of London |date=October 1887 | pages=294}}</ref><ref>{{cite book | title=Concealing-Coloration in the Animal Kingdom | url=https://archive.org/details/concealingcolor00thaygoog | publisher=Macmillan | author=Thayer, Gerald H. | year=1909 | pages=[https://archive.org/details/concealingcolor00thaygoog/page/n52 22]}}</ref>  Research indicates that the caterpillars can sense the twig's colour with their skin and match their body colour to the background to protect themselves from predators, an ability to camouflage themselves also found in cephalopods, chameleons and some fish, although this colour change is rather slower in the caterpillars.<ref name="Eacock" />

It goes into the soil late in the season, where it pupates in order to spend the winter. The imagines emerge from the pupae between late May and August, the males slightly before the females (this is common and expected from [[sexual selection]]). They emerge late in the day and dry their wings before flying that night.

The males fly every night of their lives in search of females, whereas the females only fly on the first night. Thereafter, the females release [[pheromone]]s to attract males. Since the pheromone is carried by the wind, males tend to travel up the [[Molecular diffusion|concentration gradient]], i.e., toward the source. During flight, they are subject to predation by [[bat]]s. The males guard the female from other males until she lays the eggs. The female lays about 2,000 pale-green ovoid eggs about 1&nbsp;mm in length into crevices in bark with her [[ovipositor]].

=== Resting behaviour ===
{{Pie chart
|value1 = 32
|label1 = Exposed trunk
|value2 = 11
|label2 = Unexposed trunk
|value3 = 46
|label3 = Trunk/branch joint
|value4 = 5
|label4 = Branches
|value5 = 11
|label5 = Foliage
|value6 = 4
|label6 = Artificial surfaces
|caption = Resting position of peppered moths (1964–1985). Total number of moths 109.
<ref name="Howlet 1987">{{cite journal |last1=Howlett |first1=R.J. |last2=Majerus |first2=M.E.N. |title=The understanding of industrial melanism in the peppered moth (''Biston betularia'') (Lepidoptera: Geometridae) |journal=[[Biological Journal of the Linnean Society]] |date=1987 |volume=30 |issue=1 |pages=31–44 |doi=10.1111/j.1095-8312.1987.tb00286.x}}</ref>
}}

{{Pie chart
|value1 = 48
|label1 = Trunk
|value2 = 70
|label2 = Branches
|value3 = 17
|label3 = Twigs
|caption = Resting position of peppered moths (2001–2006).  Total number of moths 135.<ref name="Cook 2012">{{cite journal |last1=Cook |first1=L.M. |last2=Grant |first2=B.S. |last3=Saccheri |first3=I.J. |last4=Mallet |first4=J. |title=Selective bird predation on the peppered moth: the last experiment of Michael Majerus |journal=[[Biology Letters]] |date=2012 |volume=8 |issue=4 |pages=609–612 |doi=10.1098/rsbl.2011.1136|pmid=22319093 |pmc=3391436 }}</ref>}}


A mating pair or a lone individual will spend the day hiding from predators, particularly birds. Males stay with the female to ensure paternity.{{Citation needed |date=March 2025}} Peppered moths generally rest in the upper part of the trees at unexposed positions. They use three main types of site: (1) a few inches below a branch-trunk joint on a tree trunk where the moth is in shadow; (2) on the underside of branches; and (3) on foliate twigs.<ref name="Howlet 1987" /> Peppered moth researcher [[Michael Majerus]] notes:

<blockquote style="font-size:100%">[[Creationism|Creationist]] critics of the peppered moth have often pointed to a statement made by Clarke ''et al''. (1985): "...&nbsp;In 25 years we have only found two ''betularia'' on the tree trunks or walls adjacent to our traps, and none elsewhere". The reason now seems obvious. Few people spend their time looking for moths up in the trees. That is where peppered moths rest by day.</blockquote>

Further support for these resting positions is given from experiments watching captive moths taking up resting positions in both males (Mikkola, 1979; 1984){{Citation needed|reason=Source given, but no source not linked|date=March 2025}} and females (Liebert and Brakefield, 1987){{Citation needed|reason=Source given, but no source not linked|date=March 2025}}.

Majerus, ''et al.'', (2000){{Citation needed|reason=Source given, but no source not linked|date=March 2025}} have shown that peppered moths are cryptically camouflaged against their backgrounds when they rest in the boughs of trees. It is clear that in human visible [[wavelength]]s, ''typica'' are camouflaged against [[lichen]]s and ''carbonaria'' against plain [[Bark (botany)|bark]]. However, birds are capable of seeing [[ultraviolet]] light that humans cannot see. Using an ultraviolet-sensitive video camera, Majerus et al. showed that ''typica'' reflect ultraviolet light in a speckled fashion and are camouflaged against [[crustose lichen]]s common on branches, both in ultraviolet and human-visible wavelengths. However, ''typica'' are not as well camouflaged against [[foliose lichen]]s common on tree trunks; though they are camouflaged in human wavelengths, in ultraviolet wavelengths, foliose lichens do not reflect ultraviolet light.

During an experiment in [[Cambridge]] over the seven years 2001–2007 Majerus noted the natural resting positions of peppered moths, and of the 135 moths examined over half were on tree branches, mostly on the lower half of the branch, 37% were on tree trunks, mostly on the north side, and only 12.6% were resting on or under twigs.<ref name="Cook 2012" /><ref name="swedentalk">{{cite web |author=Majerus |first=M.E.N.|date=August 2007 |title=The Peppered Moth: The Proof of Darwinian Evolution |url=http://www.gen.cam.ac.uk/research/personal/majerus/Swedentalk220807.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110615081639/http://www.gen.cam.ac.uk/research/personal/majerus/Swedentalk220807.pdf |archive-date=2011-06-15 |access-date=2011-02-21}}</ref><ref name="Connor 2007">{{cite news |author=Connor |first=S. |date=25 August 2007 |title=Moth study backs classic 'test case' for Darwin's theory |url=http://news.independent.co.uk/sci_tech/article2893896.ece |url-status=dead |archive-url=https://web.archive.org/web/20081007043307/http://news.independent.co.uk/sci_tech/article2893896.ece |archive-date=7 October 2008 |access-date=2007-09-09 |newspaper=The Independent}}</ref>