Category Archives: Insects

“Guava” stick insect

Guava stick insect
Guava stick insect (© Nichols Locke)

Stick insects are enigmatic creatures, blending into the forest which often makes them hard to see but then surprisingly obliging in the hand. Their Portuguese name is bicho pau or branch bug, from its mimicry of brown twigs. They often waver from side to side, again mimicking the movement of the twigs around them.

The 3,000 species, found mainly in the tropics, are from the Phasmatodea order (they do look a little phantasmagoric) and the Phylliidae family (leaf insects) feeding mainly on leaves. They play an important role in the breakdown of organic matter.

They are not easily noticeable, but our nurseryman, Jailson, has a keen eye for something out of the ordinary and brought this example, which he found in the nursery, into the REGUA Conservation Centre. This particular species is referred to locally as ‘guava stick insect’, named after it’s preference for these fruit. As you can imagine this one foot long insect caused quite a stir with the students present on a course, and after climbing on a few human hands and being subjected to a number of photos, we returned it to a safe place, tucked away back in the nursery.

Ant mimic bugs

I’ve been inspired to write about a sighting just seven metres away from the REGUA office. What seemed to be a huge ant, never spotted here before, was photographed on a leaf. We currently have an inventory of ants being carried out by Rural Federal University of Rio de Janeiro (UFRRJ) researchers. To my surprise, close examination of the antennae and feeding apparatus from the photograph revealed this ‘odd’ ant to actually be hemipteran bug – an incredible ant mimic!

Nymph of Neotropical Soybean Bug <em>Neomegalotomus parvus</em> (© Jorge Bizarro)
Nymph of Neotropical Soybean Bug Neomegalotomus parvus (© Jorge Bizarro)

It has been identified as the nymph (juvenile stage) of the Neotropical Soybean Bug Neomegalotomus parvus (Westwood, 1842) (HEMIPTERA: Alydidae), or Percevejo Formigão in Portuguese.

According to Costa Lima’s Insetos do Brasil, only the immature stages are ant mimics. Alydidae bugs, or other primitive coreoids, are closely related to Leguminosae. They are not species-specific to any Leguminosae and feed on different leguminous plants (Schaefer 1980, Schaefer & Mitchell 1983), including soy beans, with potential to reach pest status.

In the field, adults were found on carrion and faeces of animals. In a soybean field in Bela Vista do Paraíso, PR, N. Parvus were found aggregating (30 to 40 individuals) in dog faeces at the time of soybean harvest. Alydidae may feed on faeces or carrion under extreme conditions when their primary food source (legumes) is not available.

The ecological reason for why the nymphs are perfect mimics of ants is still unknown. So here is an interesting theme for research.

References

LIMA, COSTA. 1940. Insetos do Brasil. 2 Tomo, Hemípteros, ESCOLA NACIONAL DE AGRONOMIA, SÉRIE DIDÁTICA N.º 3, figs. + 351 pp.

VENTURA, MAURÍCIO U., JOVENIL J. SILVA & ANTÔNIO R. PANIZZI. 2000. Scientific Note: Phytophagous Neomegalotomus parvus (Westwood) (Hemiptera: Alydidae) Feeding on Carrion and Feces. An. Soc. Entomol. Brasil 29: 839-841.