Milkweed, Dogbane, and Insects that live on them

You've probably heard of Monarch butterflies, and you may have heard of their host plant, milkweed, and the effort to conserve and support the butterflies by planting milkweed. Milkweed is technically any species in the plant genus Asclepias. It belongs to the same family (Apocynaceae) as dogbane Apocynum cannabinum. Both types of plant host a variety of insects besides monarchs. Here are some of them.

This is common milkweed Asclepias syriaca. It can be found growing in fields and in hedgerows throughout most of the US east of the rocky mountains. The 'milk' or latex contains compounds called glycosides which make them inedible to many animals. But some insect species thrive on the plant, and even sequester the toxins. Others avoid the latex by chewing holes in the leaves to drain it. Many pollinators visit the flowers for nectar. The pollen of the flower is stored in waxy sacs called pollinia. These become attached to the bodies of larger pollinators. The complex pollination system of milkweed flowers can sometimes trap pollinators not large enough to transport the sticky pollinia.

This is an early instar monarch caterpillar Danaus plexippus. These caterpillars eat milkweed exclusively, but will feed on several species.

Here is a last instar caterpillar munching on the milkweed bud. After it has eaten all it can, it will leave and wander to find a site to transform into a chrysalis, the pupal stage of butterflies.

Here is a monarch chrysalis. The caterpillar finds a suitable spot, where is affixes itself to the branch (or terrarium in this case). It hangs upside down in a J" shape until it sheds it's last larval exoskeleton, revealing this pupal stage.

After about two weeks, the monarch pupal exoskeleton becomes transparent and you can see the adult pattern.

The adult butterfly breaks the chrysalis open and pushes its way out.

The newly eclosed monarch hangs on to the chrysalis or branch and waits for its wings to dry. It pumps fluid into the wings to expand them. It also ejects a brown fluid called meconium which is the metabolic waste materials gathered during the pupal stage.

Here the wings are all expanded and the butterfly waits for them to harden.

I placed this female on some swamp milkweed Asclepias incarnata where it can nectar and prepare for the first flight!

Monarchs are just one of the many species of insects found on milkweed though they are probably the best known.

Another caterpillar that eats milkweed is the tussock moth caterpillar Euchaetes egle.

The milkweed beetle is a "long-horned beetle" of the family Cerambycidae. It's name Tetraopes tetrophthalmus means "four-eyes" because the base of the antennae insert where the normal single pair of compound eyes would be, dividing them. Like monarchs, this beetle feeds exclusively on milkweed, and benefits from the plant toxins it ingests, which make it an unpalatable food for predators. It advertises this fact with aposematic or "warning" red and black coloration.

The large milkweed bug, Oncopeltus fasciatus belongs to the family Lygaeidae, the seed bugs. Its food is the seeds of milkweed plants, so it can commonly be found on the seed pods. Like the milkweed beetle, it sequesters the toxins produced by the plant and it also has black and red coloration. Young milkweed bugs nymphs are orange.

 The small milkweed bug, Lygaeus kalmii feed on nectar and milkweed seeds. 

A small beetle feeding on a bud.

Swamp Milkweed Leaf Beetle - Labidomera clivicollis, like other milkweed insects is black and orange. It belongs to the family Chrysomelidae. The lower photo shows the larva.

A male bumble bee Bombus sp. feeding on nectar.

A male carpenter bee Xylocopa sp. feeding on nectar.

I was very excited to find this beautiful jet-black leafcutter bee, a carpenter bee mimic Megachile xylocopoides. 

Megachile xylocopoides and some ants drinking nectar

Megachile xylocopoides

A small halictid bee drinks from the outside of the flower

Spiders love the traffic to milkweed blooms. A crab spider feeds on a small bee. In the next photo a  jumping spider waits by a blossom.

Dogbane Apocynum cannabinum is also known as Indian hemp, due to its use for fiber. It is poisonous and can cause cardiac arrest if ingested.

This beautiful beetle is the dogbane beetle, Chrysochus auratus. The species name 'auratus' means golden. They feed on the dogbane leaves and can be found on the plant thoroughout the summer

The beetles mate and lay eggs on the dogbane. The larva eat the roots.

Some sort of beetle drama?