Katydid nymph on the citrus bush on 12 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D)
Wednesday 14 January 2009
In mid-October, 2008, I noticed some tiny katydid nymphs in the backyard and I have been watching them grow over that last 3 months. One has finally reached adulthood and I thought this would be a good time to document their growth, especially now that I can more accurately identify the species.
From looking at the adult katydid, I'm fairly certain they are gum leaf katydids, Torbia viridissima. I had suspected this from the start, based on the photographs at Brisbane Insects, but needed to see the adult form to confirm. I should mention that for the bulk of the 3 months, the nymphs were on the same tree, or more accurately, the same shoots that had grown from the base of the same gum tree. While it is not possible to positively identify these as the same nymphs for the whole period, the progression in the size of the nymphs over the time is consistent with them being the same individuals.
The number of nymphs I could find at any one time varied between 1 and 5 and there are at least 2 remaining as of 13 January 2009.
I noticed and photographed the first nymph on 12 October 2008. This particular nymph was not on the gum tree but rather a citrus tree some 5-10 metres from the gum tree. It is not possible to know if this individual relocated to the gum tree, was related to the nymphs found on the gum tree or is even the same species as the others photographed. I have included it here just in case it is related or is one of the same individuals. It does look quite different from the others so it probably not the same species, but the timing is similar to the others. It was very small and it is possible they could change in appearance that much when they grow.
Katydid nymph on the citrus bush on 12 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D)
Four days later (16 October), I saw a katydid nymph in approximately the same area on the citrus bushes as the first one but this one had a different appearance to the first one. I don't know if it is the same individual or not, but this looked more like the nymphs seen later on the gum tree.
Katydid nymph on the citrus bush on 16 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
On 20 October 2008, I noticed the first katydid nymph on the gum tree. This one looks almost identical to the one photographed on the citrus bush 4 days earlier.
Katydid nymph on the gum tree on 20 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Over the following 12 weeks I took photographs of the nymphs every 4 to 15 days. I can now show a pretty good progression of the nymphs through to adulthood.
Katydid nymph on the gum tree on 24 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Katydid nymph on the gum tree on 30 October 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Gum leaf katydid nymph on the gum tree on 9 November 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Gum leaf katydid nymph on the gum tree on 19 November 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Gum leaf katydid nymph on the gum tree on 23 November 2008. (Nikon D300 with Nikkor 60mm f/2.8D and PK-13 tube)
Gum leaf katydid nymph on the gum tree on 8 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 18 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 18 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 29 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 29 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 29 December 2008. (Nikon D300 with Nikkor 60mm f/2.8D and 20mm tube)
Gum leaf katydid nymph on the gum tree on 13 January 2009. (Nikon D300 with Nikkor 60mm f/2.8D)
Gum leaf katydid adult on the gum tree on 13 January 2009. (Nikon D300 with Nikkor 60mm f/2.8D)
Gum leaf katydid adult on the gum tree on 13 January 2009. (Nikon D300 with Nikkor 60mm f/2.8D)
There is no guarantee that the individuals in the photographs are the same ones. At one point I found 5 different nymphs all of similar appearance, however, they all seemed to be growing at the same rate so even if they aren't the same individuals in the photographs, it is very likely they are all of the same age.