Monarch Caterpillars

5/31/2021, 9 am.

I haven’t been able to check on the Monarch caterpillars since last Wednesday, five days ago. I wonder what I will find today as, along with honoring our fallen heroes this Memorial Day, I have a chance to go look at “my” milkweeds again.

Some of the plants seem to have reacted to the caterpillars’ munching by wilting the affected areas, and some still look normal. I haven’t been able to find a pattern in the wilting yet. Some of my thoughts are a genetic predisposition in some plants to wilt in response to caterpillar damage, more caterpillars eating the wilted ones, or some caterpillars carrying a plant disease.

There seems to be a lot of attrition between egg and three-day caterpillar. I have only seen one dead caterpillar so far, but I have not seen evidence of nearly as many caterpillars as there were eggs. It has been cool and rainy most days since the eggs were laid; that may be hard on newly hatched critters. There were several places I saw tiny frass but no caterpillars, but there were plenty of places for teensy caterpillars to hide. If they have survived they will be much bigger today, perhaps easier to see, and I can know from their droppings if they have still been alive and growing.

5/31/2021, evening.

I made it to the milkweeds this afternoon. I found two caterpillars large enough to be from the first day of hatching (11-12 days old), I’ve been writing about our Monarch caterpillars this year. There are two posts so far, eggs and caterpillars. several a few days old. I didn’t see any hatchlings today, but I did still see a few eggs.

Monarch caterpillar munching Spider Milkweed

Small Monarch caterpillar on blooming Spider MolkweedMonarch egg May 31, 2021Survival definitely looked better on non-wilted plants—that is, all or all-but-one living caterpillar I saw today were on healthy-looking plants. I did have another thought on the damaged milkweeds. I saw a few weevils on them last week, and today I noticed some holes in the stems of wilted branches that looked like they could have come from weevils’ snouts.

I didn’t just see caterpillars. I saw Penstemon digitalis about to bloom.  I saw a bee fly and a small scorpionfly, and a beetle or two in the flowers. The Coreopsis is gorgeous yellow, and the Deptford Pinks are starting to bloom.

White Penstemon buds ready to open

Striped winged critter on Spider Milkweed
Scorpion fly, Panorpa sp., identified 6/1   (5/31 “Dobson fly comes to mind, but frankly I’m too tired to look it up tonight. Critter on Spider Milkweed today.”)

I also saw a bumblebee when I arrived. I attended the Missouri Bumblebee Atlas workshop a few weeks ago they said bumblebees visit multiple plants of one species before moving on to another. Sure enough, it visited several plants of the spider milkweed, then multiple red clover plants, then back to spider milkweed before flying away.

Getting back to the monarchs, I am eager to see how much they grow in the next few days. Of course I could look up how long they live as caterpillars before they pupate, but this time I’m hoping to see for myself.