In about a week I should be back in Mozambique and this blog will likely get more interesting. We have an exciting project developing in Gorongosa National Park, one that is bound to generate a lot of good data and influence biodiversity science in the country for years to come. More about it soon. But in the meantime I thought I would put a spotlight on a relatively little known group of organisms that one can easily see in Mozambique – the empusid praying mantids.
The family Empusidae is a small lineage of mantids, with only 28 described species found mostly in drier regions of Africa and a handful of additional species in southern Europe and SE Asia. It is one of the very few families of mantids known to be monophyletic, and it shows – they all share remarkable morphology that makes them stand out among other members of this singular order of insects. Two main body types are common – they are either thin and stick-like or, while still being rather spindly, the body is covered with large lobes and flaps, making them excellent mimics of dried, shriveled leaves.
The stick-like variety, such as the genera Empusa, Hemiempusa, and Idolomorpha, are usually found in grassy vegetation, where they hunt small insects, such as planthoppers and grasshopper nymphs. Earlier this year I ran across a gorgeous male specimen of Idolomorpha dentifrons on the Cheringoma Plateau of Gorongosa, but had troubles photographing it in a way that would properly convey its incredibly elongate morphology. In the end I took a series of vertical photos of its head and front legs that I stitched together in PS, and here is the result. Male empusids are unusual in having pectinate antennae, the kind usually seen in silk moths and other insects with well-developed pheromonal communication, where the female emits sex pheromones and males follow the faint scent trail. Not surprisingly, such behavior was recently demonstrated to be present in empusids (Gemeno et al. 2005. J. Ins. Behav. 18: 389-403).
The leaf-like morphology can be seen in the Devil’s mantis (Idolomantis diabolica), arguably one of the most striking and beautiful praying mantids in the world. The body of immature individuals resembles a dry, withered leaf, except for the brighter colors on the underside of the raptorial front legs. Adults turn pale green and white, and the pattern on their front legs becomes brightly red, resembling vivid petals of a flower. There is a reason for this – Devil’s mantids are specialized hunters of pollinators, such as bees and butterflies, and presumably this bright coloration fools some insects into coming dangerously too close.
Devil’s mantids are known to occur in woodland savannas of Kenya and Tanzania, but on my recent visit to the National Natural History Museum in Maputo I discovered in its entomological collection a few ancient specimens from various parts of Mozambique. One had been collected in the 1960’s tantalizingly close to Gorongosa. Knowing that there is a chance of being able to see this gorgeous creature in its natural habitat, I am now obsessed with trying to find it. I didn’t succeed on my recent visit to Mozambique, but maybe I’ll have better luck this time. Watch this space.