Animal Diversity Web

Ge­o­graphic Range

Danaus plex­ip­pus ranges from North and South Amer­ica and the Caribbean to Aus­tralia, New Zealand, the oceanic is­lands of the Pa­cific, Mau­ri­tius, the Ca­nary Is­lands of the At­lantic, and, most re­cently, West­ern Eu­rope.

Habi­tat

D. plex­ip­pus is a pre­dom­i­nantly open coun­try, frost in­tol­er­ant species whose range of breed­ing habi­tats is greatly de­pen­dent upon the pres­ence of as­cle­piad flora (milk­weeds). The monarch re­quires dense tree cover for over­win­ter­ing, and the ma­jor­ity of the pre­sent sites in Cal­i­for­nia are as­so­ci­ated with Eu­ca­lyp­tus trees, specif­i­cally the blue gum, Eu­ca­lyp­tus glob­u­lus. These trees were in­tro­duced from Aus­tralia and have filled the role of na­tive species that have been been re­duced by log­ging.

Phys­i­cal De­scrip­tion

Both male and fe­male mon­archs are bright or­ange with black bor­ders and black veins. The veins on the fe­male are thicker than those of the male. Male mon­archs also have a swollen pouch on both of their hind wings.

Mon­archs are poi­so­nous to ver­te­brates. Their poi­son comes from the milk­weed they feed on.

Mon­archs also use their ap­pear­ance to ward off preda­tors. Or­ange is con­sid­ered a warn­ing color, which will warn preda­tors that mon­archs are poi­so­nous, and not to at­tack them. From a dis­tance, mon­archs can blend into their sur­round­ings. Some­times, their spots will ap­pear to be the eyes of a larger an­i­mal, and will ward off preda­tors.

• Other Physical Features
• ectothermic
• bilateral symmetry
• poisonous

• Range wingspan

  8.6 to 12.4 cm

  3.39 to 4.88 in

De­vel­op­ment

Small cater­pil­lars hatch from eggs laid by fe­male Mon­archs. They grow, shed­ding their skin to get big­ger. Even­tu­ally each cater­pil­lar stops grow­ing and forms a case around it­self called a chrysalis. In­side the chrysalis it changes its body its body in a process called meta­mor­pho­sis. When it is done it emerges as an adult but­ter­fly.

• Development - Life Cycle
• metamorphosis

Re­pro­duc­tion

The mat­ing pe­riod oc­curs in the spring, just prior to mi­gra­tion from the over­win­ter­ing sites. The courtship of D. plex­ip­pus is fairly sim­ple and less de­pen­dent on chem­i­cal pheromones in com­par­i­son with other species in its genus. Courtship is com­posed of two dis­tinct stages, the aer­ial phase and the ground phase. Dur­ing the aer­ial phase, the male pur­sues, nudges, and even­tu­ally takes down the fe­male. Cop­u­la­tion oc­curs dur­ing the ground phase and in­volves the trans­fer of a sper­matophore from the male to fe­male. Along with sperm, the sper­matophore is thought to pro­vide the fe­male with en­ergy re­sources that aid her in car­ry­ing out re­pro­duc­tion and rem­i­gra­tion.

Once they reach their breed­ing grounds, the fe­males lay their eggs on milk­weed host plants. The egg and lar­val pe­riod is tem­per­a­ture de­pen­dent and lasts about 2 weeks. At the end of this pe­riod, the larva enter a pe­riod of pu­pa­tion, and after 9 to 15 days an adult but­ter­fly emerges.

• Key Reproductive Features
• semelparous
• sexual
• fertilization
  • internal
• oviparous

• Breeding interval

  Monarch butterflies mate in the spring before they migrate.

Be­hav­ior

Like birds, D. plex­ip­pus fol­lows a pat­tern of sea­sonal mi­gra­tion. There are two dis­tinct pop­u­la­tions in the North Amer­ica, those that breed in the East and those that breed in the West. Each au­tumn mil­lions of these but­ter­flies leave their breed­ing grounds and fly to over­win­ter­ing sites. The East­ern pop­u­la­tion over­win­ters in the vol­canic moun­tains of east­ern Mi­choa­can in cen­tral Mex­ico. The West­ern breed­ers spend their win­ters along the Cal­i­for­nia coast. Sim­i­lar mi­gra­tory be­hav­ior has been ob­served in Costa Rican and Aus­tralian pop­u­la­tions.

Food Habits

The larva feed on a wide range of milk­weeds of the genus As­cle­pias. From these plants they ac­quire and store car­diac gly­co­sides, sec­ondary plant com­pounds that pro­tect them from pre­da­tion. The adults of the species for­age for flower nec­tar.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Many species of milk­weed oc­cur­ring in parts of the United States and Mex­ico are known to be poi­so­nous to cat­tle ,and D. plex­ip­pus is con­sid­ered ben­e­fi­cial be­cause it helps re­duce the abun­dance of these plants. Over­win­ter­ing sites are of in­ter­est to tourists.

Con­ser­va­tion Sta­tus

The an­nual monarch mi­gra­tion is con­sid­ered a "threat­ened phe­nom­ena" by the In­ter­na­tional Union for Con­ser­va­tion of Na­ture and Nat­ural Re­sources. Steps have been taken by both the United States and Mex­i­can gov­ern­ments along with nu­mer­ous pri­vate in­di­vid­u­als and or­ga­ni­za­tions to pro­tect the over­win­ter­ing sites of these but­ter­flies.

• IUCN Red List

  No special status

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Ethan Kane (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Bop­pre, Michael."The Amer­i­can Monarch: Courtship and Chem­i­cal Com­mu­ni­ca­tion of a Pe­cu­liar Danaine But­ter­fly". pp. 29, 34 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Cock­rell, Bar­bara J., Stephen B. Mal­colm, and Lin­coln P. Brower. "Time, Tem­per­a­ture, and Lat­i­tu­di­nal Con­straints on the An­nual Re­col­o­niza­tion of East­ern North Amer­ica By the Monarch But­ter­fly". pp. 234 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Feltwell, John. 1993. The En­cy­clo­pe­dia of In­sects. Pren­tice Hall, New York. Pgs. 111, 143.

Lane, John. "Over­win­ter­ing Monarch But­ter­flies in Cal­i­for­nia: Past and Pre­sent". pp. 337 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Lynch, Steven P. and Ronald A. Mar­tin. "Milk­weed Host Plant Uti­liza­tion and Ca­de­no­lide Se­ques­tra­tion by Monarch But­ter­flies in Louisiana and Texas". pp. 107-108 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Mal­colm, Stephen B. and Myron P. Za­lucki. 1993. Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County. Pref­ace, pp. 397-398.

Mal­colm, Stephen B. "Con­ser­va­tion of Monarch But­ter­fly Mi­gra­tion in North Amer­ica: An En­dan­gered Phe­nom­e­non". pp. 358 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Schmidt-Koe­ing, Klaus. "Ori­en­ta­tion of Au­tumn Mi­gra­tion in the Monarch But­ter­fly". pp. 282 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Snook, Laura C. "Con­ser­va­tion of the Monarch But­ter­fly Re­serves in Mex­ico: Focus on the For­est". pp. 364 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Urquhart, Fred A. 1960. The Monarch But­ter­fly. Uni­ver­sity of Toronto Press, Toronto. Pg. 35.

Urquhart, Fred A. 1987. The Monarch But­ter­fly: In­ter­na­tional Trav­eler. Nel­son-Hall, Chicago. Pgs. XIX, 173-177.

Vane-Wright, Richard I. "The Colum­bus Hy­poth­e­sis: An Ex­pla­na­tion for the Dra­matic 19th Cen­tury Range Ex­pan­sion of the Monarch But­ter­fly". pp. 183 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Van Hook, T. "Non-Ran­dom Mat­ing in Monarch But­ter­flies Over­win­ter­ing in Mex­ico". pp. 49 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.

Wells, Har­ring­ton, Patrick H. Wells, and Stef­fen H. Rogers. "Is Mul­ti­ple Mat­ing an Adap­tive Fea­ture of Monarch But­ter­fly Win­ter Ag­gre­ga­tion". pp. 61 in Mal­colm and Za­lucki (eds.) Bi­ol­ogy and Con­ser­va­tion of the Monarch But­ter­fly. Nat­ural His­tory Mu­seum of Los An­ge­les County.