Phasmatodea: Ripe Cages

I reared phasmids for 14 years. Along the way I noticed a few things that came along.  My first phasmids were, adult females of Extatosoma tiaratum tiaratum and Eurycnema goliath; well doesn’t everyone? This was 1997.

I kept a journal and notes, and I was able to pull some populations studies from the data.  I just wish the Leukaemia had left me alone for long enough to get some published papers from it.

Eurycnema goliath

When I first started rearing stick insects, I kept the two species in the same cage.  Most weeks I would sort the frass to obtain the eggs, and put them into new take-away food boxes sorted by month of laying (by the way re-using actual take-away food by washing them isn’t nearly clean enough).  The eggs started hatching, and my statistics told me that it took a properly hydrated E.goliath hatchling 9 days to starve to death. Now what was I supposed to do?

Why would they starve to death?  I watched them.  They ate the leaves, and still starved to death.  By the way having an adult or slightly more mature  nymphs, the early instar nymphs can smell where to eat in the fresh bite marks.  Maybe the problem was that they were getting none of the gut flora required to eat Eucalypt leaves.  Where could it be from?  A clue: cockroach nymphs get their gut flora from eating their parent’s turds.   Could phasmids do it via a similar route?  Maybe the environment supplies it all, maybe they get their gut flora directly from the leaves they eat.  Hang on, I had already tried that one.

The entomologist’s term for the old skin when they moult to the next instar is  “Exuviae” and it is a plural (and “exuvium” is the singular and it rarely happens in nature).  Why plural? They moult both their exoskeleton, and also their complete gut lining. When a nymph turns around to eat its own exuviae it is re-swallowing the gut flora, and also recovering some of the energy and protein. It’s a pretty neat trick making proteins just using only Eucalyptus leaves.

How to make it hard for gut-flora-less hatchlings to miss their parent’s turds.  To each box of eggs I put two parent turds, crushed into a powder, and one  fresh eucalyptus leaf.  And I stopped cleaning the cages so thoroughly, I let them “age” naturally.  Nymphs have a trick where they let go with all 6 legs and float down to the ground.  And head straight in the nearest vertical thing, usually a tree.  My success rate  with E.goliath became one of my most reliable breeding lines, for over 10 years.

This is my concept of a “ripe cage”.

E.tiaratum

At this time I had ripe “nymph” cages, and I would look for hatchlings each morning.   And I made a second adult cage, so I could separate turds and put known-correct adult turds into each egg box.  And into the nymph cages.  Once they reach about 3rd or 4th instar, I would transfer them into the adult cage.  Plenty of species-correct frass for the nymphs to fall on.

And is far easier to sort eggs from frass when you only need to look for a single shape at a time.

Other species

  • I reared Acrophylla titan for many years, they are native to my suburb.  My initial problems with this species were because, they got too much to drink and it needed to be about once a month, not once a week.
  • I was never especially successful with E. wuelfingi, no idea why, anecdotally many people I knew said you got a few generations, and then stopped hatching.  The plural of “anecdote” is not “data”.
  • I reared E.tiaratum.bufonium, they are native to my suburb. People wanted to know if they are dangerous.
  • Ctenomorpha marginnipennis, also native to my suburb, and most of the Sydney Basin. This species needs to drink more often than once a week in the egg boxes
  • Didymuria violescens. Native to my suburb. These require little help from the keeper, they are one of 3 species that can explode into plague proportions, mine didn’t much, one January I wound up with 4,000 eggs.  Sorting that lot was torture.
  • P.wilkinsonii  Native to my suburb.  There are 8 red tubercles in the prothorax of nymphs, aal mostly gone by adul except on Another potential “plague” species, but mine never did.
  • T.childrenii, native to my locality.  Originally I thought I has seeing two species, with wild caught male and separately wild caught female.  Rearing eggs throught to adult, I knew it was the one species.
  • and a few more, I’d have to dig up my old notes.