Anurag Agrawal: Summer in the milkweed patch

AgrawalAnurag Agrawal is a professor in the Department of Ecology and Evolutionary Biology and the Department of Entomology at Cornell University. He lives in Ithaca, New York. His latest book, Monarchs and Milkweed, is available now.

It’s peak season for milkweed and the village of insects that make milkweed its home.  In my book on Monarchs and Milkweed, I devote an entire chapter to these diverse and fascinating other milkweed insects.  Below are photos from two days last week (July 6 and 7th), one set from my front yard and the other from Shawangunk National Grassland Preserve, both in NY State. All but two of the 11 specialized milkweed herbivores was seen on these four species of milkweed. Do you know which two species are missing?

The butterfly weed, Asclepias tuberosa.  Likes it dry.
Common milkweed, Asclepias syriaca, >90% of monarchs that make it to Mexico eat this as a caterpillar.
A. syriaca, mis-named because it was thought to be from Syria.
The purple milkweed, Asclepias purpurescens, rare in NY State, this spectacular individual was near the shawangunks.
Vegetative swamp milkweed, Asclepias incarnata.
Flowering swamp milkweed, Asclepias incarnata, complete with the swamp milkweed beetle, Labidomera clivicollis.
The poke milkweed, Asclepias exaltata, loves the partial shade. Note the nearly mature monarch.
The four-eyed milkweed longhorn beetle, Tetraopes tetrophthalmus. Note the four functional eyes!
Like all chewing insects on milkweed, Tetraopes deactivates the latex by clipping the veins.
Drippy toxic gooey stuff.
A little egg laid upon a leaf.  Monarch inside.
The first day or a monarch’s life, it makes a latex-free island before starting to feed on the leaf tissue inside the circle.
A week later, the monarch has grown 2000 times its original size.  This caterpillar has parasitic wasps eating it from the inside out.
The only fly known to eat milkweed, a leaf miner, feeds between layers of the leaf (larva is hidden here): Liriomyza asclepiadis.
Euchaetes egle, the milkweed tussock moth, a misnomer since it’s in the woolly bear family, Arctiidae.  Egg clutches hatch into hundreds of caterpillars… note the foamy fluff that the egg mass was delivered in.  These turn into large hairy orange and black caterpillars. Hmmmmm…. same colors as adult monarch butterflies.
A dead bee, like so many that get stuck in milkweed’s flowers. Why do they get stuck?
A tourist, not a real herbivore of milkweed.
Adult of the milkweed leaf beetle, Labidomera clivicollis, here on common milkweed.
Larva of the milkweed leaf beetle, Labidomera clivicollis.  Larvae of this species are apparently polymorphic, with grey or orange coloration. Closely related to the Colorado Potato Beetle.
An adult of the elusive milkweed stem weevil, Rhyssomatus lineaticollis, chewing on apical leaves of common milkweed.
Sometimes they poke the stem, as here on the poke milkweed, A. exaltata. No egg inside this one.
Other times eggs are laid in a row in the stem.
A trenched stem with milkweed stem weevil, Rhyssomatus lineaticollis, eggs.
Inside the stem, larval feeding and frass of the milkweed stem weevil, Rhyssomatus lineaticollis.
The milkweed stem weevil, Rhyssomatus lineaticollis, also deactivates the latex.  All the chewing herbivores of milkweed do it… more or less the same way, but with there own special twist.
No seed pods yet, but the small milkweed bug, Lygaeus kalmii, feeds on last year’s seeds and sucks milkweed’s sap (not the latex!) … The large milkweed bug has not yet arrived to NY State… it apparently cannot overwinter in the frozen north.
Aphis asclepiadis, one of three aphids that eats milkweed.  This species is greenish to brown to grey, typically lives on top of the plant, and is nearly always tended by ants.
And the Oleander aphid, Aphis nerii, usually bright yellow-orange.  Here with a winged adult, just founding a colony in Ithaca, NY.