Red Milkweed Beetle

The red milkweed beetle, Tetraopes tetrophthalmus. 

The red milkweed beetle is another nice summer insect. It's a longhorned beetle, in the family Cerambycidae. Check out its extreme antennae.

The red milkweed beetle's genus and species names are derived from Latin and mean four-eyed. Many species in the longhorned beetle family have antennae that originate close to the eyes, some so close that the eyes look indented. In the red milkweed beetle each compound eye is completely separated into two by the placement of the antennae and violà -- four eyes!

Click to enlarge and check out the antenna with an eye on each side. 

Red milkweed beetles are among the few things that can eat the toxin-containing plants of the milkweed genus, Asclepias. They are able to store the toxins and end up unpalatable to potential predators, which they advertise with their showy colors.

Red milkweed beetles are not the only red and black insects you can find on milkweeds. I've written about two others: large and small milkweed bugs. The red X on its back identifies this small milkweed bug, Lygaeus kalmii. 

The ones with a broad black band across the back are called large milkweed bugs, Oncopeltus fasciatus. You can read a blog I wrote previously about these bugs by clicking here.  And another blog about both kinds by clicking here. 

Combined with monarch butterflies, that are also milkweed specialists in the caterpillar stage, red milkweed beetles and large and small milkweed bugs make for exciting times in the milkweed patch for insect enthusiasts.

Milkweed Bugs, Large & Small

Last year I wrote a blog about the milkweed bug Oncopeltus fasciatus, which is also called the large milkweed bug. It's the kind I usually see on milkweed stems and leaves or sunning themselves on objects near milkweed. (Click here for that blog.)

Large milkweed bugs, Oncopeltus fasciatus, sunning on a fence rail. Adults sport a bright pattern of two black spots and a wide black band on an orange-red background. 

This week I stopped to look at the milkweed bug pictured below. It was sitting on milkweed flowers where its colors contrasted beautifully with the pink and cream blossoms. Looking more closely I saw by the pattern on its back that it was not the kind I usually see. It was the other milkweed bug: Lygaeus kalmii, also called the small milkweed bug.

A small milkweed bug, Lygaeus kalmii. The adult pattern is usually described as a red X on black, but I see a black heart and three red triangles on a red background. 

Like large milkweed bugs, small milkweed bugs also mainly eat milkweed seeds, piercing them with a sharp beak, injecting enzymes, and then sucking up the dissolved food. Both kinds of milkweed bugs also sometimes drink nectar from flowers -- the one above may have been having a sip when I spotted it.

Milkweed Bugs

If you take a close look at a milkweed plant today you will probably see crowds of yellow oleander aphids on the stems. Before long a monarch butterfly will come for a drink of flower nectar. Turn over a leaf and you'll see milkweed bugs.

Milkweed bugs, Oncopeltus fasciatus, suck juices from milkweed tissues and seeds; they have piercing, sucking mouthparts that are like sharp straws. These three are warming up on a metal fence railing in a milkweed patch. The little one is an immature stage called a nymph. The other two are adults. 

Milkweed bugs are bright red for a reason; it's a warning to anyone who might be thinking about eating one. Like monarch butterflies, milkweed bugs become poisonous from eating milkweed. A bird that eats a milkweed bug and gets sick will remember the bright colors and avoid them in the future. The strategy is called aposematic coloration.

Even among  bright red bugs this one stands out. It has just molted its skin; the remnants are still attached to its tail end. Newly emerged insects are lighter-colored than usual and somewhat soft.

Milkweed bugs have seven stages: the egg, five increasingly larger immature stages called nymphs, and the adult. They don't make cocoons. Each nymphal stage looks a little different, but none of them have wings and they can't reproduce. Like other insects the milkweed bugs have exoskeletons that make them rigid on the outside. After growing as large as the skin will allow, they shed it and come out bigger. At this time of year and you will probably easily find all the nymphal stages and lots of adults on any milkweed plant. Click here to go to a site that has a nice drawing of the stages. 

The newly emerged bug will soon darken, harden, lose that bit of old skin, and then get back to the business of eating milkweed. Mmmm... milkweed! Click on the photo to enlarge.

Milkweed World

Stop and look at a milkweed plant this week and you may see a lot of interesting and colorful insects.

Milkweed.

The monarch butterfly caterpillar, Danaus plexippus, is a milkweed specialist that eats nothing else.  

Monarch caterpillars come in five sizes. Each size is a different stage called an instar. Successive instars shed their skins and grow larger in abrupt steps. 

Check the area around milkweed plants carefully and you may find a monarch butterfly chrysalis like this. I saw a caterpillar curling up into a J shape in this spot under a fence rail yesterday. When I returned today it looked like this. A beautiful orange adult will emerge from the pearly green structure in about two weeks. 

Milkweed bugs, Oncopeltus fasciatus, suck milkweed sap; they have piercing, sucking mouthparts that are like sharp straws. These three milkweed bugs are warming up on a metal railing in a milkweed patch. The little guy is an immature stage called a nymph.

This milkweed tussock caterpillar, Euchaetes egle, will grow up to become a relatively unremarkable small brown moth. 

This is a yellow milkweed aphid, also called the oleander aphid. Aphids suck plant juices for nourishment. This adult is about a tenth of an inch long; you would have to line up a few dozen of them to make a line as long as their scientific name -- Aphis nerii boyer de Fonscoblombe.

Aphid populations grow quickly and can completely cover the stems and leaves of a plant. Tiny wasps help keep them in check. Wasps attack aphids by piercing and laying eggs inside them! The two brown aphids on the pod on the right of this photo are victims of wasp attacks; they are called mummies. Wasp larvae dine on the interiors of host aphids and eventually emerge as adults. 

Adult ladybugs like to eat aphids. (Look out little yellow guys!)

This is the ferocious larval stage of a ladybug sitting on a milkweed leaf. It eats aphids too. It came to the right place!