Monarch Butterfly Update: May 26, 1998
Today's Report Includes:
Latest Migration News and Data
Monarchs appear to have flooded into the north over the past week, with butterflies now as far as 46N and 47N. You'll find 41 new sightings today for your migration map.
Of today's 41 sightings, 12 were reported on a single day--May 19th. Do you think this is significant?
Predators and Parasites on the Prowl
I certainly was! Right before my eyes, my monarch caterpillar suddenly split open--and out crawled 3 maggots.
It was like science fiction....The white larvae, I learned later, were tachinid flies. The adult tachinid fly
lays its eggs on monarch larvae--and the young flies develop inside. Just before my monarch became a chrysalis,
the fly larvae emerged. (I was curious, so I kept them. They developed into adult flies within a few days....Not
as nice as monarchs, maybe, but fascinating.)
Keep in mind: A single female monarch butterfly can lay several hundred eggs. If they all survived, the world would be overcome with monarchs. Predators play a significant role in keeping the balance--but nobody really knows their impact on overall monarch abundance. This summer, you can help scientists study these questions. See:
Protection in the Bag!
A Monarch Watch contributor suggested protecting monarch eggs and larva by using mesh paint filter bags to cover the milkweed plants. The bags are about 5 gallon size, available at paint stores, and inexpensive.
Before covering the milkweed, carefully look the plant over and remove any existing potential predators. Then, gently pull the bag over the plant, and secure the bag at the base of the stem with a twist tie. But be careful--check the bag periodically, because one larva may eat the whole plant before you know it and need to be moved to another plant!
Monarch larvae develop through 5 stages, called "instars". Learn how to recognize each stage:
Reminder: When School's Out the Monarch Migration Will Continue
Although this is our our last scheduled update, we're not going away. We will continue to collect your monarch sightings daily. Every Tuesday, watch for a new migration map and data update until the monarchs have completed their journey north.
The Next Monarch Butterfly Migration Update Will be Posted on June 2, 1998.