Monarch Butterflies laid 1/4 of eggs on Dog-Strangling Vine (Vincetoxicum nigrum), larvae die

photo: Kitty Kohout
Dog-strangling Vine (Black swallow-wort) Vincetoxicum nigrum (L.) Moench
Vincetoxicum: from vincere for "to conquer" and toxicum for "poison"

“Haribal and Renwick (1998) found that female monarch butterflies (Danaus plexippus L.) oviposit on black swallow-wort (V. nigrum) in choice tests in the laboratory; however, resulting larvae were not able to complete development on this plant. Dacey and Casagrande (pers. obs.) found that monarchs readily oviposit on V. nigrum in the laboratory and in large cages in the field. In both cases, when monarchs were given a choice of ovipositing on common milkweed (A. syriaca) or black swallow-wort, they laid approximately 25% of their eggs on the swallow-wort, and all of the resulting larvae died. Dacey and Casagrande (pers. obs.) found eggshells as evidence of monarch oviposition on black swallow-wort in uncaged field populations of swallow-wort and milkweed.” Invasive Plants of the Eastern United States - Swallow-worts.

In Toronto we have two species of Dog-Strangling Vine /"DSV" - Pale Swallow-wort V. rossicum syn. Cynanchum rossicum and Black Swallow-wort V. nigrum . Both have been recorded since the 1800's. - Kaufman & Kaufman