Sunday, May 15, 2016

Asian Lady Beetle Larvae

Bug on the couch - REK


H. axyridi larva - Wikimedia
Barb was cutting Golden Alexander (Zizia aureus) seed heads off to prevent them from reseeding and the following morning found these colorful creatures crawling around the seed bag.  The one above was on the couch and posed for a low light portrait.  I was sure it was a larval form of a beetle or bug but couldn't come up with a match.  I emailed it to Chris Barnhart who suggested it was probably a Multicolored Asian Lady Beetle larva- Harmonia axyridis and a trip through multiple sources confirmed it.

If that name doesn't ring a bell, think back to the onset of winter when these little stinkers started invading your house or garage, crawling around and taking little annoying nips on your neck.  When you slapped one or picked it off it left a foul odor on your fingers.  I suspect you remember them now.
First instar (emergent larvae) with empty egg cases - Barry Grivett
They only take between 3 to 4 weeks to go from a little egg packet attached under any of a wide variety of leaves, four larval stages and a pupa to an adult lady beetle. They can have multiple generations a year leading to the heavy infestations we see in the fall.  The larvae feed on a variety of aphids, a plentiful food source.  The adults can live more than a year, the perfect trait mix for an invasive species.  If this weren't enough advantages, consider their defenses:
"Like other lady beetles they use isopropyl methoxy pyrazine as a defensive chemical to deter predation, but also have this chemical in their hemolymph at much higher concentrations than many other such species, along with species/genus-specific defensive compounds such as harmonine. These insects will "reflex bleed" when agitated, releasing hemolymph from their legs. The liquid has a foul odor (similar to that of dead leaves) and can cause stains. Some people have allergic reactions, including allergic rhinoconjunctivitis when exposed to these beetles."
Cannibalization? A firm prolonged grip on the head - REK
It must have seemed like a good idea back in 1916 to release them for aphid control.  It wasn't until 1988 when they were found in the wild.  Now they threaten some of our native ladybirds and other aphid eaters, both by competing for resources and in some cases actually attacking them.  They are known to cannibalize their species, especially if they aren't from the same brood.  I suspect that is what is going on in this video of the two in the picture above.

  • Looking for help in identifying a bug?  Bi-State Bugs is a new Facebook page focused on Missouri and Illinois with a lot of heavy hitters following it to answer questions or just admire your latest find. 

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