I have no clue what happened here

Last weekend I went with on a field trip to Guáquira Ecological Station in Yaracuy, Venezuela. During a walk to one of our field sites we passed a group of plants in the family Musaceae, and a small protrusion caught my eye. On the side of the leaf stems I saw a katydid in the subfamily Conocephalinae, tribe Copiphorini staying very still. As I got closer, I could see that it was dead. What was interesting is that it died while, apparently, laying eggs:

Laying eggs?

Laying eggs?

But there was something that didn’t quite add up. Upon closer inspection, the insect was fixed to the side of the stem only by the ovipositor, and there were no eggs to be found.

Oviposicion-02

The legs were awkwardly folded underneath, it looked faded and it was in a conspicuous position; it had many signs of having been infected with a parasitic fungus, except there were no spores, fungus body or anything that looked like fungus. Very odd indeed. Then I looked at the other side, and things got stranger:

Parasitoid exit hole

Parasitoid exit hole

That looks like a parasitoid exit hole, which makes little sense, at least from what I’ve seen in the field. I usually see these exit holes in eggs, larvae or pupae, not adults, but it’s possible. There are tangle-veined flies (Nemestrinidae) that have been reared from katydids, as well as some tachinids like Homotrixa alleni, but nemestrinids and most tachinids are larger than this exit hole. So what could this be? A random occurrence? A parasitoid that modifies the host’s behavior and makes it die while making an attempt at laying eggs? A katydid that had a parasitoid inside it and then got infected with a fungus that modified its behavior, but the parasitoid ate the katydid from the inside out before the fungus could? I have no clue; all I know is that I’ll keep my eyes open in case I see something similar next time I go! If anyone has a clue about this, I’d love to know!

 

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Wasp-mimicking katydids

Imagine yourself in a tropical jungle. You see a medium sized insect, about 3.5 cm long, land on a light trap. Its body is elongated, metallic black with a bluish hue, bright orange wings and long orange and black antennae. It walks around moving its antennae really fast. What could it be?

– “Dan, It’s a tarantula hawk, a wasp in the family Pompilidae, duh!

Not so fast! In the insect world, things aren’t always what they seem, and this is a fine example:

Aganacris

This jaw-dropping katydid (Tettigoniidae; Phaneropterinae) belongs to the genus Aganacris, and it mimics a pompilid wasp (Pepsis are relatively common here and have very similar colors) with remarkable accuracy. Aposematic wasp mimics are common in the insect world; you can see many examples in flies (Syrphidae), moths (Sesiidae) and beetles (Cerambycidae), but seeing it in a katydid was a first. As it turns out, wasp mimicry in tettigonids is pretty rare; Nickle and Castner studied the strategies against diurnal predators used by this group in Perú, and most of the groups were leaf/bark/twig/lichen mimics; only two genera, Aganacris and Scaphura, were found to be wasp mimics. [1]

This is another first for me (I mentioned pentatomids making insect smoothies earlier), and I couldn’t be happier. Even though I’ve been to this particular biological station quite a few times, every time I go there I see something new and simply astonishing.

1.- David A. Nickle and James L. Castner, 1995. Strategies Utilized by Katydids (Orthoptera: Tettigoniidae) against Diurnal Predators in Rainforests of Northeastern Peru. Journal of Orthoptera Research, No. 4, pp. 75-88. http://www.jstor.org/stable/3503461