I did a milkweed survey for eggs and larvae over the course of this Easter weekend (3/31/18 and 4/01/18). I looked at milkweed in several different sections, some in the upper pastures and some in the lower pastures. I also explored the bottomland area that had been flooded on April 28th after heavy rainfall from thunderstorms caused the creek to overflow.
Here are the results of this weekend’s milkweed survey. I looked at 326 milkweed plants and found a total of 189 eggs and 107 larvae.
These are the egg count results:
200 milkweed w/0 eggs ~ (64 of these milkweed had 1 or more larvae on them)
91 milkweed w/1 egg
19 milkweed w/2 eggs
8 milkweed w/3 eggs
6 milkweed w/4 eggs
1 milkweed w/5 eggs
0 milkweed w/6 eggs
1 milkweed w/7 eggs
These are the larvae count results:
61 1st instars
28 2nd instars
15 3rd instars
3 4th instars
The bottomland where flowing flood waters had occurred had a high percentage of milkweed with eggs compared to the rest of the surveyed sections. I had seen two monarchs actively laying eggs in this area on the morning following the storms and flooding. There were also a good number of 1st instars and 1 2nd instar in areas I knew were completely underwater. This seems to mean that some of the eggs remained viable while underwater and hatched successfully in the next few days. There was a 3rd and a 4th instar on some tall milkweed “towers” on slightly higher ground in the flood area. Their milkweed plants had been tall enough and sturdy enough to keep them above the water flow that occurred on their “island.”
Here are the counts specifically in the flooded area. I looked at 52 milkweed plants and found 54 eggs and 15 larvae. Of the 15 larvae found, there were 12 1st instars, 1 2nd instar, 1 3rd instar, and 1 4th instar. These counts are already included in the general survey above.
This is a photo of the 4th instar larva that I found on one of the tall & sturdy milkweed "towers" in the flooded area.
Latitude: 30.4 Longitude: -95.8
Observed by: Kathy
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