Gwyfynod
Cymraeg

When they fly

Are the moths flying earlier than they did? The same two windows as the changes page, but with every week weighted by the nights trapped in it.

40 Earlier
16 Later
25 Did not move

The median species has not moved at all. But of the 56 that did move, 40 advanced and only 16 were delayed, a split too lopsided to be chance (p = 0.0018).

Why not the obvious calculation

The weeks the lamp could run shifted by −2 weeks between the two windows, so comparing dates alone would partly measure the calendar rather than the moths. Only weeks 10 (Mar)–43 (Oct) are compared, the ones trapped in both windows, and each week's contribution is divided by the nights trapped in it. The raw calculation returns −1 weeks; the weighted one 0.

Weeks dropped for falling in only one window: 3, 4, 5, 6, 7, 8, 44, 45, 46, 48, 50, 51, 52.

At least 10 moths on each side.

species early median late median shift moths
red twinspot carpet Xanthorhoe spadicearia 32 · Aug 22 · May −10 17 / 12
honeysuckle moth Ypsolopha dentella 33 · Aug 23 · Jun −10 29 / 33
double striped pug Gymnoscelis rufifasciata 30 · Jul 22 · May −8 26 / 13
poplar hawkmoth Laothoe populi 28 · Jul 23 · Jun −5 20 / 11
light brown apple moth Epiphyas postvittana 39 · Sep 35 · Aug −4 36 / 70
small angleshades Euplexia lucipara 26 · Jun 22 · May −4 64 / 30
spectacle Abrostola tripartita 27 · Jul 24 · Jun −3 30 / 17
green carpet Colostygia pectinataria 28 · Jul 25 · Jun −3 21 / 11
small phoenix Ecliptopera silaceata 32 · Aug 29 · Jul −3 36 / 20
clouded bordered brindle Apamea crenata 25 · Jun 23 · Jun −2 57 / 48
dusky brocade Apamea remissa 27 · Jul 25 · Jun −2 44 / 35
foxglove pug Eupethecia pulchellata 26 · Jun 24 · Jun −2 22 / 18
july highflier Hydriomena furcata 31 · Aug 29 · Jul −2 13 / 11
muslin footman Nudaria mundana 27 · Jul 25 · Jun −2 46 / 28
middle barred minor Oligia fasciuncula 25 · Jun 23 · Jun −2 23 / 13
gold spot Plusia festucae 31 · Aug 29 · Jul −2 30 / 18
silver ground carpet Xanthorhoe montanata 25 · Jun 23 · Jun −2 49 / 25
heart & dart Agrotis exclamationis 26 · Jun 25 · Jun −1 606 / 77
flame Axylia putris 26 · Jun 25 · Jun −1 148 / 55
broom moth Ceramica pisi 25 · Jun 24 · Jun −1 62 / 77
sallow Cirrhia icteritia 36 · Sep 35 · Aug −1 29 / 15
ingrailed clay Diarsia mendica 26 · Jun 25 · Jun −1 27 / 11
small sq spot Diarsia rubi 35 · Aug 34 · Aug −1 220 / 141
common marbled carpet Dysstroma truncata 36 · Sep 35 · Aug −1 113 / 31
common footman Eilema lurideola 30 · Jul 29 · Jul −1 64 / 59
common carpet Epirrhoe alternata 32 · Aug 31 · Aug −1 114 / 37
barred straw Gandaritis pyraliata 28 · Jul 27 · Jul −1 31 / 15
small fanfooted wave Idaea biselata 30 · Jul 29 · Jul −1 51 / 26
bright line brown eye Lacanobia oleracea 28 · Jul 27 · Jul −1 109 / 38
clouded silver Malacosoma neustria 23 · Jun 22 · May −1 10 / 14
clay Mythimna ferrago 29 · Jul 28 · Jul −1 10 / 11
smokey wainscot Mythimna impura 30 · Jul 29 · Jul −1 224 / 93
l b-b yellow underwing Noctua janthe 33 · Aug 32 · Aug −1 137 / 78
small dotted buff Photedes minima 26 · Jun 25 · Jun −1 74 / 13
straw dot Rivula sericealis 29 · Jul 28 · Jul −1 84 / 40
early thorn Selenia dentaria 30 · Jul 29 · Jul −1 48 / 27
white ermine Spilosoma lubricipeda 25 · Jun 24 · Jun −1 78 / 205
buff ermine Spilosoma luteum 26 · Jun 25 · Jun −1 50 / 45
dark barred twinspot carpet Xanthorhoe ferrugata 32 · Aug 31 · Aug −1 74 / 37
setaceous hebrew character Xestia c-nigrum 36 · Sep 35 · Aug −1 13 / 31
common grass veneer Agriphila tristella 32 · Aug 32 · Aug — 250 / 34
dark arches Apamea monoglypha 29 · Jul 29 · Jul — 289 / 157
garden tiger Arctia caja 27 · Jul 27 · Jul — 15 / 24
beautiful golden y Autographa pulchrina 25 · Jun 25 · Jun — 76 / 51
antler Cerapteryx graminis 31 · Aug 31 · Aug — 31 / 38
purple bar Cosmorhoe ocellata 32 · Aug 32 · Aug — 23 / 19
elephant hawkmoth Deilephila elpenor 25 · Jun 25 · Jun — 61 / 67
burnished brass Diachrysia chrysitis 28 · Jul 28 · Jul — 23 / 20
purple clay Diarsia brunnea 27 · Jul 27 · Jul — 39 / 15
drinker Euthrix potatoria 30 · Jul 30 · Jul — 73 / 63
snout Hypena proboscidalis 29 · Jul 29 · Jul — 71 / 28
riband wave Idaea aversata 29 · Jul 29 · Jul — 49 / 36
truelovers knot Lycophotia porphyrea 29 · Jul 29 · Jul — 78 / 87
common rustic Mesapamea secalis 32 · Aug 32 · Aug — 688 / 130
lesser yellow u'wing Noctua comes 34 · Aug 34 · Aug — 142 / 86
least yellow underwing Noctua interjecta 32 · Aug 32 · Aug — 18 / 10
large yellow u'wing Noctua pronuba 32 · Aug 32 · Aug — 613 / 343
brimstone Opisthograptis luteolata 27 · Jul 27 · Jul — 161 / 73
hebrew character Orthosia gothica 16 · Apr 16 · Apr — 275 / 234
swallowtailed moth Ourapterix sambucaria 29 · Jul 29 · Jul — 19 / 10
feathered ranunculus Polymixis lichenea 39 · Sep 39 · Sep — 20 / 10
flame carpet Xanthorhoe designata 32 · Aug 32 · Aug — 67 / 23
dotted clay Xestia baja 30 · Jul 30 · Jul — 62 / 17
squarespot rustic Xestia xanthographa 35 · Aug 35 · Aug — 495 / 80
early grey Xylocampa areola 12 · Mar 12 · Mar — 53 / 15
small wainscot Chortodes pygmina 35 · Aug 36 · Sep +1 115 / 11
lychnis Hadena bicruris 24 · Jun 25 · Jun +1 17 / 11
rosy rustic Hydraecia micacea 35 · Aug 36 · Sep +1 52 / 35
clouded border Lomaspilis marginata 28 · Jul 29 · Jul +1 31 / 18
flounced rustic Luperina testacea 34 · Aug 35 · Aug +1 63 / 44
flame shoulder Ochropleura plecta 28 · Jul 29 · Jul +1 390 / 202
garden carpet Xanthorhoe fluctuata 33 · Aug 34 · Aug +1 28 / 18
six striped rustic Xestia sexstrigata 32 · Aug 33 · Aug +1 53 / 40
double square spot Xestia triangulum 28 · Jul 29 · Jul +1 105 / 39
silver y Autographa gamma 33 · Aug 35 · Aug +2 110 / 29
peppered moth Biston betularia 25 · Jun 27 · Jul +2 20 / 16
straw coloured grass veneer Agriphila straminella 30 · Jul 33 · Aug +3 107 / 28
common quaker Orthosia cerasi 11 · Mar 14 · Apr +3 253 / 71
red chestnut Cerastis rubricosa 11 · Mar 15 · Apr +4 35 / 21
clouded drab Orthosia incerta 11 · Mar 16 · Apr +5 96 / 24
pebble prominent Notodonta ziczac 23 · Jun 31 · Aug +8 11 / 12

This does not say moths fly earlier. It says a tail of species has moved earlier while most have not moved at all, and that difference matters.