Subject: What is it?
Location: New Jersey
July 13, 2014 8:46 pm
I saw this bug sipping the nectar of a butterfly weed plant – asclepias.
Thanks so much for your help!
Signature: Bridget
Dear Bridget,
We now do most of our research online, but in the case of your unusual beetle, we turned to our brand new copy of Beetles of Eastern North America by Arthur V. Evans and we quickly identified your beetle as Macrosiagon flavipenne, one of the Wedge-Shaped Beetles in the family Ripiphoridae. According to Evans: “Adult Ripiphrids live for only a few days and information on their lives is fragmentary. They rest on low grasses or flowers and meet in mating swarms. The comblike antennae on the male persumably increase its ability to locate females emitting sexual pheromones. … All species undergo hypermetamorphosis. Early instars feed internally on the larvae of other insects, whereas the later stages feed externally on their hosts. … Macrosiagon larvae parasitize wasps in several families, including Vespidae, Sphecidae, Crabronidae, and Tiphidae. Of the species Macrosiagon flavipenne, Evans writes: “Abdomen black (male) or red (female). … Adults active in summer, found mainly on flowers.” There is a differing spelling of the species name on BugGuide, where it is listed as Macrosiagon flavipennis. BugGuide also notes: “Females lay eggs on flowers. Eggs hatch into an active larva that attaches itself to visiting wasp. It is carried back to wasp nest where it burrows into a host larva.”
Thank you so much for identifying the beetle. I’ve been trying to figure it out for days. You’re the best!