Butterflies in Winter in Iowa

A message with photograph this week from alert reader Ken Wiggers asked about a tattered butterfly seen on the ground, near the woodpile in mid-March! As shown below, the butterfly is the mourningcloak butterfly, Nymphalis antiopa, an attractive butterfly up to 3 inches across and with dark purple wings that have a wide creamy yellow border at the outer edge. This is not our most common or best-known butterfly, but it is one routinely seen around the state. The mourningcloak is not unique, but it is among a small handful of species of butterflies that indeed do survive the long, bleak, Iowa winter in the adult stage.

  Winter can be a tough time to be alive in Iowa. Animals and plants that live and prosper here do so by having some “trick” to escape the inhospitable weather.   Shorter day lengths and changes in moisture and temperature can trigger insects to enter a period of reduced activity accompanied by changes in metabolism and behavior. This period of inactivity, called diapause, can occur in any insect life stage, though for each different species, diapause occurs at the same stage, every time.   Insects in winter diapause are protected by antifreeze-like compounds that protect against ice formation within the body.  Insects in diapause need a little energy that they get by digesting their stored body fat.   Iowa butterflies survive winter in different ways and in different stages as shown in the accompanying table.    Our best-known butterfly, the monarch, doesn’t stay in Iowa at all. The adults we saw last fall were all headed to central Mexico where they will rest until spring. Any that stayed in Iowa rather than go south with the others froze to death long before now. Other species migrate away or die out every year in Iowa and are replenished by northward migrants the following year.   Swallowtail butterflies such as the black swallowtail that develops from a caterpillar that ate your dill plants last summer spend the winter right out there in the thick of the weather. The chrysalis was strapped to standing host plant debris last summer and will wait there until spring before finishing the metamorphic process.   The cabbage white butterflies that come from the imported cabbageworm caterpillars that were eating your broccoli and cabbage foliage last summer are also waiting for spring as chrysalides.   Only a few butterflies, like the mourningcloak, already mentioned, are able to make it through the Iowa winter as an adult. The brightly colored panted lady and red admiral may hibernate as adults or migrate away to warmer climates to survive.   It's a wonder anybody survives in Iowa through the winter, but if butterflies can make it, so can we.



Mourningcloak butterflies spend the winter in the adult stage and appear in very early spring.Mourningcloak butterflies spend the winter in the adult stage and appear in very early spring.

Overwintering Stage of Common Iowa Butterflies
  Name Overwinter Stage E = Egg; L = Larva or caterpillar P = Pupa or chrysalis; A = Adult
Swallowtails (Family Papilionidae)  
      Black Swallowtail (Papilio polyxenes)   P
      Giant Swallowtail (Papilio cresphontes)   P
      Tiger Swallowtail (Papilio glaucus)   P
Skipper (Family Hesperiidae)  
      Silver-Spotted Skipper (Epargyreus clarus)   P
Whites and Sulphurs (Family Pieridae)  
      Cabbage White (Pieris rapae)   P
      Clouded Sulphur (Colias philodice)   L or P
      Orange Sulphur = Alfalfa (Colias eurytheme)   L or P
Gossamer‑wing Butterflies (Family Lycaenidae)  
      Spring Azure (Celastrina ladon)   P
      Eastern Tailed‑Blue (Everes comyntas)   fully grown L
Brush‑footed Butterflies (Family Nymphalidae)  
      Monarch (Danaus plexippus)   migrates, repopulates
      Common Wood Nymph (Cercyonis pegala)   L
      Pearl Crescent (Phyciodes tharos)   partly grown L
      Silvery Checkerspot (Chlosyne nycteis)   partly grown L
      Eastern Comma (Polygonia comma)   A
      Question Mark (Polygonia interrogationis)   A
      Great Spangled Fritillary (Speyeria cybele)   L newly emerged
      Variegated Fritillary (Euptoieta claudia)   A
      Hackberry Emperor (Asterocampa celtis)   L half grown
      Mourningcloak (Nymphalis antiopa)   A
      Painted Lady (Vanessa cardui)   migrates, repopulates
      Red Admiral (Vanessa atalanta)   migrates, repopulates;   possibly P or A
      American Lady (Vanessa virginiensis)   migrates, repopulates; possibly   A
      Viceroy (Limenitis archippus)     partly grown L
      Buckeye (Junonia coenia)   migrant in Iowa
      American Snout (Libytheana carinenta)    migrant in Iowa
      Red-spotted Purple (Limenitis arthemis)   L

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