By Rick Mikula (Feb. 2018)
Well so far so good. There haven’t been any killer storms or drowning rains in the over wintering sites. In fact the weather has been just right for the Monarchs, cool, damp and overcast, just the way they like it. Cooler conditions work to the Monarchs advantage because they use less energy when temperatures are lower. When they arrive in Mexico they are living off their stored fat reserves (lipids) that can actually carry them through the winter without any other food. The average winter temps at the sites are the perfect conditions and the lipids will last for the entire stay. However if the winter is warmer than normal the butterflies can burn these lipid reserves too quickly and not have enough to make it back north. This year they were lucky because there weren't any devastating January storms or February heat waves so things look good.
The newest problem facing the Monarchs in Mexico are the illegal avocado plantations found inside reserve. Michoacán is the biggest avocado-producing state in Mexico and unfortunately it is also where part of the reserve is located. Avocados are the most lucrative legal crop Mexican farmers can grow and the avocado trade employs nearly 100,000 people in the area. Because of the demand for this crop the Michoacán loses about 15,000 to 20,000 acres of forest land annually to avocado plantations. It the process large swaths of pine trees are cut down to make room for avocado trees. The pines trees provide thermal cover at roosting sites and once removed the monarchs could freeze to death. Another problem facing the migrators is if the weather is too nice. In Spring of 2017 temperatures warmed up a bit too suddenly. The monarchs had started their northward migration on March 1st and people were reporting extremely early sightings which was very encouraging. Unfortunately the monarchs were more ready than the milkweed was. The temps rose faster than the milkweed could respond and as the monarchs entered the US there wasn’t enough milkweed ready for egg laying. However despite this bad start they had a big finish with greater Fall numbers being reported than the past several years. And it appears the they are still rebounding, slowly but still rebounding.
So we don’t want another milkweed starved Spring for our gravid guest searching for nurseries. It’s time to start your milkweed now. By the time you collect your flats, soil, seeds and senses they will be back and looking for host plants.
Seedlings can easily be started indoors under artificial lighting or in a sunny window and eventually transplanted outdoors just after your ‘average’ date of last frost. Of course if you are using a Monarch Migrations Station as a greenhouse or cold frame you don’t have to worry about frost.
If seeds are started indoors they will take about 4-8 weeks of growing time before they can be transplanted. An easy way to start your plants is by using common plastic ‘flats’. Fill the flats with your soil mix and thoroughly soak the soil. Next sow the seeds by scattering them on the soil surface 1/4-1/2 inch apart and then cover them with about 1/4 inch of additional soil mix. Now mist the newly added soil until it is nice and damp. Cover the flat with a clear plastic cover or a plastic wrap to keep the seeds from drying out while germinating. Most seeds should germinate in 7-10 days.
Once your seedlings have emerge the soil should be kept moist by watering the flat from the bottom and not from above. The easiest way to water from the bottom is by placing the flat in a sink or large pan filled with water. Once the soil surface feel wet to the touch you can remove the flat from its bath and allow to drain. The soil should be kept moist but not soaking wet to prevent mold and fungal growth that can kill your plants.
If you prefer to plant seedlings, seeds can be started super fast by placing them between the layers of a folded up paper towel. Soak the paper towel and place inside of a plastic zip lock bag. Place the bag in a sunny window and if the paper towel is kept damp you will have sprouts in 3 or 4 days. Place the sprouts into flat and let the soil do the rest. Handling young seedlings like this can cause a lot of stress for both you and the seedling.
Regardless of how you start your seedlings they can be transplanted when they are about 3-6 inches in height. However before transplanting they will need to be acclimated to outdoor conditions for a few days. This is easily done by placing the flats outside in a sunny sheltered area during the day and then bringing them back in at night. This procedure should be repeated for 4-7 days depending on the outside temperatures. The newly transplanted plants should be watered frequently and can eventually be fertilized 2 or 3 times during the growing season.
There are over 160 different types of Milkweed in the US and most are not toxic. The roots contain the lowest amount of toxins with the highest levels being in stems and leaves. The milky latex sap can cause permanent eye damage and skin rashes.
- Species with whorled, narrow leaves are typically more toxic than species with broad leaves.
- Asclepias labriformis is said to be the most toxic
- Common milkweed, syriaca is only slightly toxic to humans.
*Please note to be always very careful when working with milkweeds of any kind and always wear gloves.
The reason milkweed latex is so harmful to your eyes is that the cardenolides in the latex can cause a temporary dysfunction of cornea referred to as Corneal oedema. This is actually a swelling of the cornea caused as the endothelial cells responsible for pumping fluid out of the cornea stop functioning. With A. curassavica the effects can last from 24 to 48 hours whereas problems associated inflammation due to contact with A. fruticosa could go on for days even with treatment.
Even very young seedlings can cause adverse skin reactions with many people. So it is very important they we remind anyone working with milkweed to be very vigilant, wear gloves and use the utmost care. Even seedlings can have enough resinoids stored to cause an inflammation of the skin known as atopic dermatitis. Acute atopic dermatitis can produce weeping, oozing areas of very itchy skin. If it does cause an irritation completely wash the area and use a hydrocortisone ointment to reduce redness and itching. Remember to NEVER touch your hands to or near your eyes until you have washed your hands.
Monarch preferred milkweeds for egg laying;
- Asclepias curassavica (Non-indigenous Tropical Milkweed)
- Asclepias incarnata
- Asclepias sullivantii
- Asclepias syriaca
- Asclepias speciosa
- Asclepias exaltata
- Asclepias hirtella
- Asclepias tuberosa
- Asclepias verticillata
The new villain on the block seems to be Asclepias curassavica ‘Tropical Milkweed’. Planting Tropical Milkweed it in your area will not stop the monarchs from migrating! It is only hardy up to zone 8B and will die off by the end of summer with the first frost if you have any that has not been eaten by then. Not only is A. curassavica their first choice for egg laying it also has a medicinal effect on monarchs infected with protozoa and infected females will seek it out to both lay their eggs and self medicate.
A very easy site to navigate to find you probable last date of frost please visit, https://garden.org/apps/frost-dates/
To track the Spring time return of monarch butterflies please visit, https://www.learner.org/jnorth/maps/monarch_spring2018.html
To follow the springtime sprouting of milkweed around the country please visit, http://www.learner.org/jnorth/maps/milkweed_spring2018.html
To follow monarch watch on Facebook please visit, https://www.facebook.com/monarchwatch/
And to keep up to date with all butterflies related topics please visit, http://www.butterflywebsite.com
Catalina Trail, then known as Cathy Aguado was the women on the cover of National Geographic in 1976 that announced the location of the monarch overwinter sites.
This entry was posted on March 9, 2018.