Archive for the ‘Pyrginae’ Tag

CUCKOO WASPS:  A DAZZLING PARASITE   2 comments


Wildlife, nature, fauna and flora of Costa Rica.

Now the weather has taken a significant change.  The rains that are expected to fall in September have started in earnest.  The rain is now falling all day and on most days.  This is good news for the frogs and this year the breeding continues on without a drop in intensity.  Every night there are large numbers of calling males.  The females are obviously responding because every morning there are lots of freshly spawned eggs.

After 17 years of data collection for my study, “Using amphibian and butterfly populations as a measure of environmental health”, I have decided to call it a day and now have to sit down and analyze the data.  Essentially I have been collecting data on population dynamics of butterflies and amphibians as well as recording daily weather conditions.  I look at changes in butterfly populations measured against temperature and amphibian populations measured against precipitation.  There are a great many other variables to be taken into consideration but watch this space for news of what the data might be showing us.

Butterflies in the Sun

Due to the constant rain and the trails running like streams, I have not been able to spend as much time outside as I would normally wish.  However, on the one day I did manage to get out and take some photographs I was rewarded with a mixed bag of goodies of which only one was new to me.

One morning the sun was shining and the butterflies were taking advantage of its warming rays.  The Lantana camara bushes are always a big nectar draw for the butterflies and this day proved to be no different.  Although there were nowhere near the number of species found during drier periods of the year there were enough to try and take a few shots.

One very small but distinctive butterfly that I have a particular liking for, (I don’t know why), is the Tropical Checkered Skipper, (Pyrgus oileus).  It is a fairly common skipper with a wide geographical distribution from southern North America and through into Costa Rica.  At a distance the black and white checkered pattern make it stand out against the green of the grass where it is normally found flying close to the ground.  When seen close up the wings and body are covered in a grey/blue fur.  The females tend to be a darker overall color.  The caterpillars feed on plants in the family: Malvaceae, of which there are several species growing in abundance locally.

Rainforests. Butterflies. Costa Rica. Veridion Adventures. Hesperiidae. Pyrginae. Pyrgus oileus.

Tropical Checkered Skipper, (Pyrgus oileus)

They belong in the family: Hesperiidae and the subfamily: Pyrginae or Spreadwing Skippers due to their habit of basking with the wings wide open.  There are approximately 50 species in the genus: Pyrgus and they can be found throughout Europe, Asia, North, Central and South America.  You are more likely to find Tropical Checkered Skippers in open sunny locations which is where I found this one.

Feeding on the nectar of the same patch of Lantana was yet another Spreadwing Skipper but one which looked completely different to the Checkered Skipper.  This was a Long-tailed Skipper, (Urbanus proteus), notable for the two long tail-like extensions of the hind wings.  There are several species of Long-tailed Skippers in the immediate area but each one has distinctive markings to the wings.  The dorsal surface of the abdomen and the wings are covered in metallic green hairs.  Again it is a widespread species ranging from southern North America, down through Central America and into South America.  The larvae feed on leguminous vines of which there are many species growing locally.  In North America it is sometimes considered a pest as it feeds on commercially grown beans.

Rainforests. Butterflies. Costa Rica. Veridion Adventures. Hesperiidae. Pyrginae. Urbanus proteus

Long-tailed Skipper, (Urbanus proteus)

This individual can be seen using its proboscis to probe for and suck nectar from the Lantana blooms.  One of the changes I have documented over the past 17 years is the progressive increase in annual average temperatures. One of the impacts this may have on butterfly populations is with increasing temperatures there will be increasing evaporation of the nectar.  This in turn causes an exponential increase in nectar viscosity.  We could end up with a situation whereby if the temperature increases to the point where the nectar is too viscous for the butterflies to suck up, then they may well not be able to feed, bringing about starvation, death and a collapse in butterfly numbers.  This is one of many variables I have to take into consideration when looking at the fact that we have had a 35% decline in butterfly species over the past 17 years.

Cuckoo Wasps: A Dazzling Parasite

While watching the butterflies flit back and forth, only stopping momentarily to take a feed of nectar, I noticed a tiny metallic green insect, only about 10mm long.  It was on top of a leaf at eye level and not moving.  It was striking in that the green was very reflective, it looked like a piece of metallic foil.  I was looking at a Cuckoo Wasp.  I have only ever photographed one in the past so if this one did not move then here was a second opportunity beckoning.  I slowly lifted the camera and got the shot but as I moved my position for a head on photo it took to the air and disappeared.

Cuckoo wasps are solitary wasps of the order: Hymenoptera, which includes bees, wasps and ants amongst others.  They belong in the family: Chrysididae, after the Greek word Chrysis – golden vessel.  They are also known as Jewel Wasps and they certainly have a jewel-like quality to them.  The refraction of light produces the spectacular metallic coloration, similar to the iridescent blues of the Blue Morpho butterflies.  In this case it is the multi-layered waxy cuticle of the wasp’s exoskeleton that produces the refraction.  There are about 3,000 named species of Cuckoo Wasps and they are found in most parts of the planet.

Rainforest insects. Hymenoptera. Chrysididae. Cuckoo Wasp.

Dazzling parasite, Cuckoo Wasp, (Chrysididae sp)

The name Cuckoo Wasp refers to the fact that, depending on species, they are either parasitoids or kleptoparasites preying upon other wasps.  Like any parasite dealing with a dangerous host it has to have evolved behavioral methods that allow it to get in and get out without being discovered or be killed.  To that end it has a very sneaky strategy.

A female Cuckoo Wasp will case the joint she is about to infiltrate.  She watches and waits for a female Digger Wasp to begin making a burrow.  When the Digger Wasp starts to bring in paralyzed prey on which to lay her eggs, the Cuckoo Wasp either hangs onto the immobilized victim and will be dragged into the burrow, or she waits until the Digger Wasp has left on another foraging trip and she will stealthily slip into the burrow.  If caught in the act, all is not lost.  Some species of Cuckoo Wasp have a concave underside and can roll into a ball.  The sting of the enraged host will not penetrate the heavily pitted exoskeleton of this now globe-like emerald.  The host has to physically carry the Cuckoo in the nest out in its jaws where it will then sit and watch till it can strike again.

Having subverted the hosts defenses, the female Cuckoo Wasp lays its eggs.  Some species are kleptoparasites, once the egg hatches and the larva emerges it will kill and eat the host larva and then consumes the food the host female is providing for it.  It remains undetected by mimicking the chemical signature odor of the host.  Others wait for the host larva to grow and then kill and consume it before it pupates.  Then like its avian namesake, it is the Cuckoo that thrives within the nest of its unwitting host and eventually emerges as a new parasite.  They parasitize a wide variety of hosts from solitary wasps and bees, to sawflies and walking sticks.  Unlike many other wasps where the ovipositor is modified into a lethal sting, the Cuckoo Wasp has a modified ovipositor and reduced venom sac so has no potentially lethal means of attack or defense.

Who would of thought as I photographed this gorgeous glowing emerald insect that it would have such an insidious life history.

A Collection of Queens

Another wasp nest that I have been walking past over the past month or so has been not only gradually increasing in size but is now populated by more adult wasps tending it.  It is the nest of one of the Social Paper Wasps, (Polistes sp).  The original queen had created a few cells beneath a leaf in each of which she laid an egg.  The eggs hatched, the larvae she provided with a food of chewed up insects until they were large enough.  She then capped the cell of the now pupa and waited for it to emerge.  The new wasp is one of the original queen’s offspring and like their mother they are equally capable of mating and reproducing.

Rainforest insects. Paper Wasps. Hymenoptera. Vesperidae. Polistinae. Costa Rica. Veridion Adventures.

Female Paper Wasp, (Polistes sp), guarding her nest.

To begin with they help with the nest, building more cells, tending the larval siblings, foraging for food and helping the nest to increase in size.  The cells are constructed from masticated vegetative material.  Prey is caught and chewed up for the larvae to feed.  The sting is only used defensively.  They will attack any potential predator that approaches too close.  So, my approach was one of great stealth.  I took a few took a few exposures but the flash was beginning to antagonize them and one took flight and started buzzing around my head which was my cue to slowly back off and leave them to their business.

The other females usually have reduced ovarian systems but dominance of the original queen is not always assured.  Fights break out and a new queen can become established within the hierarchy taking over the major reproductive role.  When the male wasps emerge, they may stay on the nest for some time before leaving.

Philip Davison Is a Biologist, Writer and Photographer Based in Costa Rica

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SKIPPERS: BEST SEEN IN CLOSE UP   1 comment


 

Wildlife, nature, fauna and flora of Costa Rica.

Today started overcast and showery.  I knew it was going to an in day.  I was in town, then I was in my cabin doing research and then I was in the office typing everything up.

Two birds turned up today that I haven’t seen for some years; the Variable Seedeater, (Sporophila americana), and the Western Wood Pewee, (Contopus sordidulus).    The Variable Seedeater is a tiny bird which normally feeds on grass seeds.  The taxonomy of the bird is uncertain as it, as its name suggests, is highly variable and many of the assumed subspecies will interbreed.  The Pewee is one of the Tyrant Flycatchers of which there are 78 different species in Costa Rica.  It can normally be found on a high perch in a tree from where it sallies, catching insects before returning to the same perch.  The individual I saw today was in the company of a pair of Tropical Kingbirds, another species of Tyrant Flycatcher fairly common in the area.

On my way back from town to the lodge, I shared the taxi ride with two of our newly arriving guests.  During the course of the conversation I was asking them how much wildlife they had seen on their previous 10 days travelling around the country.  They  had seen a lot and reeled off a short list of expected sightings from this stage of the trip.  Several hours after arriving at the lodge I saw them again and asked how they had settled in.  The list of sightings they gave me for having been on the grounds for just one or two hours far exceeded all of their sightings in the preceding week and a half.

I do try to impress upon people that when they come to the Osa Peninsula that they are visiting a very special area.  If it is the last stop on your vacation you will very quickly become aware of the fact that you saved the best till last.

A little later in the day the clouds cleared and we actually witnessed a sunset.  As it was getting darker, I was walking behind the pond, where some well established Screw Pines had been dropping fruit.  The fruits somewhat resemble larger pineapples made up of faceted segments.  One particular White-nose Coati has been feeding here for several days, but this evening he was joined by two butterflies attracted to the sap of ripening fruits; Taygetis andromeda, a satyrid, and Caligo eurilochus, which is one of the owl butterflies.  The butterfly is named after the large and obvious spot on the hind wing which looks like the eye of an owl but it does act more as a bullseye serving as a target to deflect the strike of a predator to a non-essential part of the body.  The owl butterflies are large and have a typically slow lazy flight.  They are generally seen flying at the forest edge at dusk.

Skippers: Best Seen In Close Up

 

Rainforest butterflies. Costa Rica. Hesperiidae. Pyrginae. Staphylus mazans. Mazans Scallopwing. Veridion Adventures.

Mazans Scallopwing, (Staphylus mazans)

 

Rainforest Butterflies. Costa Rica. Hesperiidae. Pyrginae. Tropical Checkered Skipper. Pyrgus oileus. Philip Davison. Veridion Adventures.

Tropical Checkered Skipper, (Pyrgus oileus)

Skippers, you probably wouldn’t even notice them.  Many of the skippers are small, less than the size of your little fingernail, chocolate brown in color and fly close to the ground.  Even when you do capture one on camera, the diagnostic features required to identify it may not be obvious.  Quite often the female has different coloration and markings to the males.  Literature pertaining to skippers, guides and keys; they are all sadly lacking.  Skipper identification is therefore left to the experts and even then that may take some time.  I too, initially paid small attention to them, at least until I started to photograph them.  For whatever reason they seem to be sensitive to sound, light or the slightest movement, so when it comes to capturing the image you have spent so long composing, as the lens focuses, off they go.  If using flash, you also need to be using a high shutter speed because if you are using anything below 1/250 sec all you will have taken is a photograph of is the leaf where the skipper had been perched.

Anyway, I have posted a few shots so you can see with patience it can be done.

Rainforest butterflies. Hesperiidae. Hesperiinae. Anatrytone potosiensis. Costa Rica. Veridion Adventures.

Anatrytone potosiensis at rest

Rainforest butterflies. Hesperiidae. Hesperiinae. Anatrytone potosiensis. felipe del bosque. Veridion Adventures.

Anatrytone potosiensis with flash

 

 

Philip Davison Is a Biologist, Writer and Photographer Based in Costa Rica

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