Today I did a survey of the milkweed in our pastures checking for monarch eggs and larvae. I looked at a total of 387 individual milkweed plants (Asclepias viridis). On these plants I observed 313 monarch eggs and 110 monarch larvae.
The specific numbers are as follows:
218 milkweed w/0 eggs
88 milkweed w/1 egg
42 milkweed w/2 eggs
21 milkweed w/3 eggs
14 milkweed w/4 eggs
3 milkweed w/5 eggs
0 milkweed w/6 eggs
1 milkweed w/7 eggs
1st instar larvae = 61
2nd instar larvae = 42
3rd instar larvae = 7
In some cases a milkweed plant had both eggs and larvae.
I started the survey around noon. It had been a foggy morning and now was overcast with a temperature of 71 degrees F, 93% humidity, and a light breeze from the east ~ perfect for close inspections of milkweed.
I noted that some of the milkweed had been damaged by the two nights of freezing temperatures earlier in the week, especially the tall, slender variety. These were often browning and wilting.
A large number of the 1st instars I saw today were newborns: 37 of the 61 1st instars looked like they had just hatched today.
Of the 313 eggs I observed today, at least 15 looked ready to hatch.
By 2:30pm it was 75 degrees F, now partly cloudy with the sun coming out more and more, 82% humidity, still a light breeze from the east. Throughout the afternoon I saw monarchs, some flying, a couple of females egg-laying, and some nectaring. But my focus was looking down at the milkweed, so I was not being observant of the monarchs.
Later in the afternoon, my son, Noah, came out and helped me with the survey, taking notes as I checked the plants. I am sure that overall I missed some of the eggs and larvae ~ they are very small and I was trying to be cautious about disturbing them.
The number of eggs on individual milkweeds is lower than was seen on the last survey of March 28th. In that survey there were quite a few instances of milkweed with 8+ eggs. Thankfully, the monarchs have more milkweed to choose from now.
This is a photo of a 3rd instar monarch larva munching on the buds of a milkweed crown.
Latitude: 30.4 Longitude: -95.8
Observed by: Kathy
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