Monteith's Leaf Insect, Phyllium monteithi Brock and Hasenpusch, in Detail

Monteith's Leaf Insect, Phyllium monteithi Brock and Hasenpusch,  has been noted in this blog on several occasions. Females are very rarely found. They seem to be restricted to the rainforest canopy and are reluctant to fly, if they can. Only a single female has been discovered in several years of searching by many local enthusiasts. Males come to lights and one was found in mid-May, rather late in the season. This one seemed especially photogenic and lent itself to some close-up photography.

The front femora are flattened and irregularly armed on the anterior margin. The internal base of the femur is "excavated" to accommodate the head and protruding eyes. The front tibiae are less produced and the internal margin is not armed. The head is notably flattened and bears the ocelli.

The antennae are fuzzy throughout but the tips are different.

The "flagellum" of the antenna is composed of elongate segments covered with fine setae. But the tips bear much shorter segments that are bare. What could be the function of this? Scanning electron micrographs might reveal different sorts of chemical and tactile receptors in each region of the antenna.

The top of the head bears the base of each antenna, the compound eyes and three ocelli. The ocelli are found in most insects are said to vary in function from one group to another. Flying insects like this one have larger ocelli and they are usually positioned as a triangle atop the head.

 This schematic representation of an ocellus illustrates that it bears a lens element and a number of photoreceptors. But it is a different photo-receiver from that of the compound eyes. The latter are much more complicated. These ocelli may serve as a light metering system for the insect. They cannot receive form. They may serve in stabilising the insect during flight. Some suggest they may have a role in receiving polarised light.