Cracking New Nymphs and Dwarves   2 comments


Philip Davison. Costa Rica. Blog. Nature Diaries

Wet Nights

The heavy rains have continued through into this week.  The heavens generally open later in the evening which is an ideal situation as the next morning the sun rises with a blue sky which leaves the day free to explore and take photographs. Well that happens on some days but progressively it has been raining late afternoon and sometimes continuing over night into breakfast time.  The creek is running with water again, at least in the upper and lower stretches but it will take a little longer for the full flow to resume.

An Explosion of Nymphs

One noticeable feature of this week has been an explosion in butterfly numbers both in terms of species and individuals.  More particular this has been the case with three particular species of butterfly in the Nymphalid family; the White-banded Peacock, (Anartia fatima), the White Peacock, (Anartia jatrophae), and the Tropical Buckeye, (Junonia evarete).  Not one of these three species is rare or uncommon and they can be found in greater or lesser numbers throughout the year depending upon season.  They do have cyclic emergences which suggest two broods may occur over the course of a year but over the last week significantly all three have suddenly emerged in huge numbers.

Anartia fatima

White-banded Peacock, (Anartia fatima)

Anartia jatrophae

White Peacock, (Anartia jatrophae)

It may well be that the rains arriving in April along with high temperatures have meant that the larval food plant of these three species has been able to produce a lot of vegetative growth which in turn has provided a sufficiently adequate amount of food to support a greater number of caterpillars.  The White-banded Peacock and the White Peacock caterpillars both feed on similar plants, namely those in the family Acanthaceae.  The Tropical Buckeye feeds on plants in the family Verbenaceae but in Costa Rica it is not known of which species.  Significantly all three species are found in open habitat such as grasslands rather than within the forest.  For that reason their presence is more obvious in the gardens around the lodge.

Junonia evarete

Tropical Buckeye, (Junonia evarete)

A New Cracker

As well as all of the peacock and buckeye butterflies flying around there are also large numbers of the Green Urania moths still residing in the locality.  But they are not the only lepidoptera to be observed.  This wet season seems to have been favorable to many other species, some of which live in the forest and others at the top of the canopy.  I have lived in the area for sixteen years and part of my research is the monitoring of butterfly populations.  In that time I have recorded 380 species at ground level in the area.  Some of those species occur regularly but there are others that I have only seen once and then never again.

There are several species of cracker in this locality.  They most certainly are not a commonly observed butterfly.  Last week I was returning to the lodge after photographing some other butterflies when I noticed on the side of a tree a species of cracker that I had not previously recorded from this area, the Red Cracker, (Hamadryas amphinome).  It is always sod’s law that if I see a new butterfly species that I am generally not carrying the camera.  This time I was.  The lighting was good and the subject was in the perfect position so I got a good shot.

Hamadryas amphinome

Red Cracker, (Hamadryas amphinome)

The male crackers typically perch on the side of tree trunks with the head facing down.  The name refers to their habit of emitting an audible cracking sound.  Research has shown that the cracking sound is made following the upsweep of the wings which make contact at high speed at the top of the stroke.  One of the wing veins is expanded which acts as a resonating chamber to amplify the sound of the crack.  It is assumed that the cracking is made by the males as part of the territorial or mating behavior but results are not as yet conclusive.

Sleeping Sulfur

One butterfly commonly seen flying around the garden areas is the Cloudedless Sulfur, (Phoebis sennae).  It bright lemon yellow coloration is immediately catches your attention as it flutters its way across the lawns.  But despite the fact that it is reasonably common it is extremely difficult to photograph.  The adult rarely seems to land and when it does it is only for fleeting moment before it is off again.  You have to be fortunate enough to be in the right place at the right time.

Phoebis sennae

Cloudless Sulfur, (Phoebis sennae)

At night however they sleep, for the most part under wide leaves close to the ground.  As long as you work without too much disturbance this then provides an ideal opportunity to capture its image as it is not moving at all.  Too much light will cause it to wake and it may fly off in a very bewildered fashion.

Confusing Swallowtails

There are two species of butterfly to be commonly found in this area which are almost impossible to tell apart.  They are both commonly known as Giant Swallowtails.  The two species in question are Heraclides thoas and Heraclides cresphontes.  The males can be distinguished under close scrutiny but the females provide more of a challenge.  In fact the best way to distinguish the females is to watch and see which plants they visit to lay their eggs; H. thoas only uses plants in the pepper family; Piperaceae whereas H. cresphontes uses a whole variety of genera in the family; Rutaceae.

Heraclides thoas

Giant Swallowtail, (Heraclides thoas)

The caterpillars are quite distinct and the fact that they feed on different food plants makes identification easier.  They both resemble bird droppings being shiny and brown with creamy patches.  H. thoas has one creamy patch while H. cresphontes has two.  I found this group of H. cresphontes caterpillars quite low to the ground on a small shrub which within a day or two they had consumed and the caterpillars themselves had disappeared.  A bird dropping is not going to appeal as a food source to many animals so the caterpillars can feed in the open without too much concern of being preyed upon by larger predators such as birds and lizards.  The deception might not prove successful against parasites and parasitoids though.

Heraclides cresphontes

Giant Swallowtail, (Heraclides cresphontes), caterpillars

Galling Sight

A close look at some of the plants as you walk around the trails will reveal various oddly shaped structures which suggest something has gone wrong with the leaf development.  To a certain degree this is true.  These weird, and to some people, ugly growths are leaf galls.

Leaf galls are the plants reaction to the invasion of another organism and there are many organisms that can induce gall development including bacteria, fungi, nematodes insects and arachnids.  The appearance of the gall is host specific so for those who study galls, cecidologists, the organism causing the gall can be identified very quickly.  Sometimes an infestation may occur but for the most part the gall producers do not harm the host.

Plant Gall

Unidentified Plant Galls

With insect induced “closed” galls, the adult lays an egg within the leaf tissue.  The egg hatches and when the larva emerges contact between the larva and the meristematic vegetative tissue causes excess cell multiplication thereby forming the gall.  The larva develops within the gall protected by its walls and feeding from the underlying starch and sugar rich tissue.

Because the gall causing agents are so numerous it requires the eye and the knowledge of an expert to be able to effect an identification.  My guess is that these galls were caused by an insect possibly in the Order: Diptera.  I would welcome any input from a gall expert who may be browsing these pages to help reveal the causal organism of these galls.

Lying Low

Bird nests are one of those things that can generally only be found serendipitously.  Hummingbird nests despite their small size are the most commonly seen of the nests as they tend to be built in more open locations either secured to a small branch or fastened with spider web beneath the tip of a Heliconia or palm leaf.

However on occasion something will catch your eye that isn’t all that it seems.  Only about eight feet off the ground just to the side of the trail I found what looked like a tangle of fallen vegetation.  But there was something about the way it was lying in the fork of a small tree that did not appear random.  A look with the binoculars I could see that top of a birds head poking out above a moss-lined cup on top of the tangle.  There was not much to see but I was reasonably sure it was a female Golden-crowned Spadebill.  I returned several times to hopefully get a picture of her sitting on the nest but with no luck.  I didn’t want to cause any disturbance so I just photographed the nest without its owner.

Platyrinchus coronatus

Golden-crowned Spadebill, (Platyrinchus coronatus), nest

Raining Dwarves

One evening in the restaurant following the nightly deluge a small distinctively patterned  snake was found lying on the wall, a Dwarf Boa, (Ungaliophis panamensis).  It is not a snake that is frequently seen as it inhabits the canopy where it can be found occupying the inner recesses of larger bromeliads.  I have found them around the lodge several times over the years.  This one may have been knocked out of the tree tops by the torrential downpour that had just occurred.

Ungaliophis panamensis

Panamanian Dwarf Boa, (Ungaliophis panamensis)

They are called Dwarf Boas because they never grow to a size larger than 2 feet in length.  Due to the small size the adults probably prey upon frogs and lizards found amongst the epiphytic growth at the top of the trees.

Philip Davison is a Biologist, Writer and Photographer based in Costa Rica.

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2 responses to “Cracking New Nymphs and Dwarves

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  1. The Red Cracker really is cracking. Stunning.

    Liked by 1 person

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