The inquiries began last Spring after the announcement of another low monarch butterfly overwintering population in Mexico. "Where can I find monarch eggs to grow to help the population?" Well, the answer seemed easy at the time - grow a large milkweed patch and they will come. Earlier we updated the Southwest Monarch Study webpage with links to local milkweeds as well as a special link on creating a Monarch Waystation with plant recommendations by elevation. But the emails for eggs and larvae continued. And continued. And continued.
Over the summer months we heard about large mass rearing of monarchs in some states. In some cases where larvae were distributed for everyone to have a monarch caterpillar grow in their yard, they weren't healthy. Some didn't survive, others couldn't fully eclose (emerge from its pupal case), were very small or had difficulty flying.
In late July in Phoenix with temperatures hovering around 110°, we received a call from a ranger who reported a monarch along the Salt River. She sent a photo to be sure it was a monarch (it was) and she was laying eggs on Desert Milkweed, Asclepias subulata. A few of us went to monitor the area and counted her eggs. None of the 15+ eggs developed even though they looked fertile.
In early August we received an email requesting a large number of tags by a person who said she had large numbers of monarchs in her yard. This was only days before our record 117° heat wave. After monitoring monarchs in the Phoenix area for many years we have a good idea of their range of absence/presence and monarchs are absent during the summer months. But we are always open to rare sightings. Upon further investigation I learned this individual was a butterfly farmer. A butterfly farmer will raise butterflies and sell them. The problem was monarchs do not thrive or naturally reproduce successfully in Phoenix with our high summer temperatures. Normally monarchs are found in the higher elevations during the summer months where it is cooler.
In early August we received a request from a teacher in the middle elevations of Arizona to visit their classroom to share information about monarchs. They had already ordered monarch larvae from a butterfly farm but they all died, so they were receiving a second batch by mail for the students to watch grow. A Southwest Monarch Study volunteer visited the classroom and brought a wild monarch to tag when she saw the condition of a freshly eclosed monarch from the butterfly farm. So we discussed her concerns and talked her through how to test for OE. Out of 40 larvae, only six successfully became an adult. Of those many had high levels of OE and others did not look healthy. We are sending the samples to Monarch Health for confirmation.
In our recently published, "Status of Danaus plexippus in Arizona" we found that while Ophryocystis elektroscirrha (OE)
levels were low in Arizona at 4% in the wild monarch population, in the
few tested farmed monarchs they were much higher at 29%. While we do not know the current OE levels for other
states in the Southwest, based on our experience here in Arizona, we
would urge caution until more is learned. Sick or infected monarchs are
often still well enough to breed and can spread diseases unnecessarily.
As a result of the increase of communications requesting a source for monarch eggs and larvae to help increase the population as well as the increase in reports of OE in farm monarchs, the Southwest Monarch Study has joined other monarch scientists and conservationists in recommending against encouraging mass breeding of monarchs in the wild or obtaining farm monarchs due to the increasing chances of spreading diseases to our healthy population here in Arizona. While we applaud the
intentions of those who would release monarchs to replenish the
dwindling population, releasing infected butterflies may be doing more
harm than good. Please take a few moments to read the full statement on Captive Breeding and Releasing Monarchs here. This doesn't mean you shouldn't protect monarch eggs or larvae in your yard in an enclosure if you wish and then tag and release them afterwards. Just be sure to follow the protocols for safe rearing to keep your cage healthy and enjoy them.
How can you best help monarchs? Grow milkweed. Grow spring nectar plants to nourish monarchs when milkweed is up but not yet in bloom. Grow stands of fall nectar to fuel their migration.