sarahkeenihan

Day 38. Spitfire

In September 2012 on September 19, 2012 at 2:01 pm

My 7-year old daughter has a wonderful teacher who excels in many things. These things do not include insect wrangling.

This morning she sent me the photo shown here, with the message,

What the hell. A random black cluster of writhing black spikey mean wormie things near my front door. Please explain, Sarah Keenihan, you’re the science person!

Only too happy to oblige, I turned to my most sciencey, nerdy and steeped-in-tradition method of research. Social media. Facebook and twitter, stat.

@Mozziebites or any other entomologists/nature enthusiasts know what these critters are? En masse in #adelaide this am (with photo attached).

Within minutes, my buddy James Hutson (@jameshutson) had replied on Facebook:

These?

and posted a link to a web page at the Australian Museum: http://australianmuseum.net.au/image/Steel-blue-Sawfly-larvae

In almost perfect synchrony, Remma Rattan (@reemarattan) replied on twitter:

Sawfire larvae, also known as spitfire.

With a name to work with, I then turned to my trusty friend Professor Google and hence found lots of further information on a ‘bug of the month’ page at Museum Victoria:

  • Steel Blue Sawflies are native to Australia, and closely related to wasps. The adult insect does not bite however;
  • The name ‘sawfly’ derives from a ‘sawbench’ under the abdomen of the female with which she lays eggs;
  • The larvae (which feature in the photograph) hatch and feed on gum leaves, grouping together for protection in a rosette pattern, similar to the head-outwards stance adopted by Bison when under attack. This is known as a ‘ring defence’, or cycloalexy. As the larvae grow, they collect in larger groups around branches during the day and spread out to feed at night.
  • When ready to pupate, the larvae leave the host tree and burrow down to make mass cocoons in the soil. Here they sit through spring and summer to emerge in early autumn. Adults have no mouthparts and do not feed, living only for a week or so;
  • Sawfly larvae have an unusual defensive mechanism that has given them the name ‘spitfires’. They store eucalyptus oil in a small sac in their gut, and regurgitate this oil when under threat. Despite their nickname, they are unable to actually spit this fluid and the oil itself is harmless unless eaten (like all eucalyptus oil). In fact it has a very pleasant eucalytpusy smell.

With this new information, and given that ‘spitfire’ is not accurate, I think we should come up with a new nickname for the Steel Blue Sawfly .

Oil vomiter? Eucalyptus breath? Gum dribbler?

Love to hear your ideas.

P.S. Let the record show that entomologist @MozzieBites later replied to conform Reema’s response

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