Many, Many Monarch Caterpillars

September 22, 2015

Monarch butterflies have been present in the GNG all spring and summer, but during this time very few larvae have been seen – until now.  Over 75 caterpillars are currently munching away on nearly every milkweed plant in the garden!

Like so many gardens in Southern California, the GNG has Tropical Milkweed planted to give a ready food source to Monarch larvae.  But because Tropical Milkweed’s natural range extends only as far north as Mexico it is not native to Southern California.  Tropical Milkweed comes from a steadily warm climate and thus wants to grow year-round. Monarchs coordinate their reproductive cycle with their environment, so gardeners need to be responsible and cut back this non-native in the fall.  In this way, we can simulate our native Narrowleaf Milkweed’s cycle of loosing its leaves by forcing the Tropical Milkweed plant to go dormant in the winter and not producing any new growth until the following spring.

By November 1st, the GNG will trim back the stalks of its Tropical Milkweed to a height of about 6-8”, re-cutting the milkweed plants every few weeks if leaves re-sprout.  This will discourage Monarchs from breeding and prematurely laying their eggs on fresh leaves. Cutting back the milkweed will also help to eliminate OE spores that may be present on the plant.  After February 1st, as winter is nearing its end, the plants will be allowed to grow-out, thus continuing the natural rhythm of the food plant for larvae of one of our most beautiful butterflies!

Monarch larvae - Danaus plexippus, nearly ready to pupate.
Monarch larvae – Danaus plexippus, nearly ready to pupate.

Recent Journal Posts