Sunday, July 19, 2009

Milkweed Critters

Common milkweed (Asclepias syriaca) is an attractive host plant for insect species. The species most associated with milkweed is probably the Monarch butterfly, which can be found in all stages of its lifecycle around milkweed plants. However, many other insects seek the nectar of milkweed flowers or chew on its leaves and pods. Below are a few insects that I found on milkweed plants at the Griggstown Grassland Preserve. While I saw a few Monarchs fluttering about at the preserve, I did not get a chance to photograph any.

First is a Small Milkweed Bug (Lygaeus kalmii). It bears close resemblance to the Large Milkweed Bug (Oncopeltus fasciatus) and Box Elder Bug (Boisea trivittata). All three species are very common with a wide distribution. Small Milkweed Bugs have a distinctive red 'X' on their backs and other more subtle differences with the other two bugs. I only saw a few Small Milkweed Bugs yesterday.

Second, we have a swarm of aphids on a milkweed pod. I think that these are Oleander Aphids (Aphis nerii), which are very common on milkweed plants. According to the Kaufman Guide, these aphids extract toxins from milkweed as they feed to defend against predators.

Finally, the most numerous insect I saw around milkweed plants yesterday was the Red Milkweed Beetle (Tetraopes tetrophthalmus). The Red Milkweed Beetle is a member of a genus that contains 13 species that specialize in milkweeds. This is the common eastern form.

Apparently love was in the air for milkweed beetles, as I saw several pairs mating.