Mantids, some would argue, represent the highest pinnacle of insect predatory body plan. With extremely good eyesight perched on a rotating head and a pronotum held diagonally that is armed with a pair of raptorial claws that can deliver lightning-fast strikes, it’s easy to see why the belief is almost universal. Add to that an acute killing instinct and you have a predator that so few in the animal kingdom can match, at least in the matters of behavior and morphology.
Some mantids take the body plan to extremes, where features appear to take on plant parts to better provide concealment both from prey and predators. Some employ disruptive outlines, such as those seen in the dead leaf mantis (Deroplatys), violin mantis (Gongylus), orchid mantis (Hymenopus), and the devil’s flower (Idolomantis). Some smaller species have patterns and demeanor that allow them to merge with mossy and lichenous tree bark such as bark mantis (Amorphoscelis) and the mossy mantis (Haaniella).
And then there are the twig mimics like the alien head (Idolomorpha), branch mantis (Neodanouria), the twig imitator (Popa), and our very own stick mantis (Tagalomantis), the subject of our inquiry. However, body morphology is only one of two ways that a mantis can be successful in its niche. Defensive behaviors such as threat displays and crypsis, wherein an animal assumes the appearance of an inanimate object to avoid detection, has become widespread in the Order Mantodea which conveys its role in the attainment of these insects as top predators.
Tagalomantis was erected as a genus by Morgan Hebard in 1920 for Euchomena manillensis, which was described by Swiss mineralogist and entomologist Henri Louis Frédéric de Saussure in 1870; it was based on a single male specimen said to have originated in “Manilla”. The following year, Saussure provided more detailed description using the same male specimen.
In 1916, Ermanno Giglio-Tos united all Oriental Euchomena- E. manillensis included – under the genus Euchomenella which he established that same year. Four years later, Hebard acquired a second specimen from Los Baños, Laguna which allowed him to provide a much detailed description, resulting in his creation of the genus Tagalomantis, with the name bearing an obvious allusion to the Tagalogs.
The genus remained in obscurity due to the general preference among mantid entomologists to uphold Euchomenella, until Tagalomantis was resurrected in 2001 by R. Roy. Tagalomantis is included in subfamily Deroplatyinae, which includes the very popular Deroplatys. The genus contains two species, the other being T. brevis from northern Sulawesi. Tagalomantis manillensis is known from the province of Laguna and the island of Panay, although I have also encountered these in the province of Quezon, right at the Laguna-Quezon border. The Luzon-Panay distribution may be disjunct, but populations still unknown may reside on the intervening islands.
Predator and prey
Tagalomantis is a forest-dwelling species that is encountered in a variety of forest types, from old growth forests, secondary forests, and even in stands of fruit and lumber trees. However, they seem to avoid heavy shade, preferring slightly open and drier situations with dappled light. In the wild I often see this species on shrubs, thin vines, rattan, trees, Pandanus, and ferns including tree ferns. As noted by Schwarz (2017), a mixture of both living and dead plant matter is essential for T. manillensis, with living plant matter attracting potential prey items, while dead and decaying ones providing camouflage.
It is usually not easy to spot these mantids, as they often perch in a disorder of vegetation, although usually close to the ground. Like many mantid species, T. manillensis are always seen on the look-out for prey, with raptorial claws ready to snatch anything that comes nearby. But when approached by what it perceives to be a potential threat, they fold their forelegs and press the body against the substrate and the hind legs are stretched out in line with the body, perhaps as a means to get rid of incriminating shadows.
Another concealment behavior is typical of many mantids wherein they will move to the side opposite to the perceived menace. If this fails or if the substrate won’t allow them to maneuver to the reverse side, they present their slim flanks to the hypothetical threat, apparently to avoid exposing the dorsal outline. In instances when If sufficiently agitated, they have the habit of dropping to the ground in a similar fashion to what some truly cryptic phasmids does, such as in the genus Mnesilochus. In these instances, they run but if held or momentarily stopped, will fold their forelegs and assume a twig-like appearance.
The defensive repertoire of T. manillensis is among the most varied among the mantids, although threat displays such as those seen in Idolomantis or even the use of the forelegs to grasp attackers such as that frequently employed by Hierodula, have so far not been observed. While they can certainly fly, they do so only in short and low bursts. These insects rely heavily on crypsis to dissuade would-be threats.
Grasshoppers and crickets figure prominently in their diet, although they will feed on any suitably-sized arthropod even in captivity. Nocturnal activity begins at dusk and in the early evening hours, when these mantids begin to climb to more exposed locations, lending the idea that during the day, T. manillensis balances its activity between hunting for prey and hiding from visually-oriented predators such as birds. Still, tackling large prey during the day lends the mantids vulnerable to detection by predators and so the preferred prey items are typically small. This changes by nighttime when no such pressure exists and they are more predisposed to hunt down suitably larger prey.
Young and old
Nymphs and sub-adults appear rather dissimilar to adults, being more elongated and slender, with a profile that is reminiscent of Statilia. Adults, particularly males have very different profiles, resembling double-edged knives but the coloration is still cryptic. Unpatterned individuals have been encountered, and they have the ability to match their coloration to the surrounding vegetation, although green individuals are as yet unknown. These stick mantids are moderately sized, with females reaching total lengths of about 8 cm, the males marginally shorter. The pronotum have clearly serrated margins, and there is a small but distinct bump on the prothorax’s dorsal side. This bump is very useful in identifying individuals that are not yet fully mature, because, as mentioned above, these do look similar to Statilia.
Copulation is very rarely observed, and there appears to be no record of one occurring for animals in captive conditions. Females lay their drawn-out ootheca on similarly elongated leaves or fronds and exhibit parental guarding. Females are so committed to guarding the ootheca that they won’t leave and eat at all, unless a prey wanders very closely by. Schwarz (2017) reported the growth of thin algae and moss mats on the pronotum of the females, as a result of their stationary behavior during brood care. Such growths have only been documented on the Neotropical shield mantis genus Choerodadis (Lucking 2010).
No one knows the status of T. manillensis populations. The Panay population studied by Schwarz (2017) appear intact, but that applies only to the Sibaliw station, where the studies were conducted. In his paper, he discussed the extensive loss of forest cover on intervening islands which may have held populations of this species, and thus the low likelihood that any still survives. One also must keep in mind that the species name refers to Manila, and it does not demand much to the imagination to infer that whatever population the metro used to hold has become extirpated. However, this is one of the most common mantis species I encounter in both the provinces of Laguna and Quezon, particularly in more suitable and less disturbed habitats. And if situations do not change drastically in the coming years, future naturalists will still be able to enjoy observing this very interesting Philippine endemic in the wild.
This appeared in Animal Scene magazine’s August 2019 issue.