Changing Bugs and Beetles   1 comment


Felipe del Bosque Blog Sept 21 2010

Temp High 88°F  Low 73°F          Precipitation 0.58 ins

It has been another typical late September day in the rainforest, overcast, grey and raining.  When I first moved out to Costa Rica to live, so many of my friends, family and colleagues were voicing a certain envy of the vicissitudes of my life, heading out for an existence blessed with permanent sun, sand and surf.  Many people tend to overlook the rain part of rainforest and so this time of year you are fortunate if you ever  see the sun.  Having said that, back in England, it is not possible to wear little more than jeans and a T-shirt for twelve months of the year, so I am not complaining.

But I am complaining about the inability to get out and about today.  I managed to have a short walk but there were no exceptional sightings.  I did notice some fungi had sprung up overnight on one of the Bosque sign posts, by tomorrow they will be gone.  It was a photographic opportunity so I had to take it.  As ever I have no I.D. but I do have the image.

The rain had let up enough by the time the sun had set to allow me to go out and carry out a frog count.  There were the usual five species around the pond; Marine Toad, Red-eyed Green Treefrog, Banana Frog, Smokey Jungle Frog and the Tink Frog.  Some nights the inventory is increased by other species but the famous five are generally always there in greater or lesser numbers.  There were several new clutches of eggs from the two different species of Red-eyed Green Treefrog deposited around the pond vegetation.

I am rapidly approaching the completion of this year’s frog counts.  My studies at Bosque del Cabo are concerned with climate change and how that effects the fauna and flora of a tropical lowland wet forest.  I measure the weekly average number of individual frogs I find on a nightly basis against the average rainfall for the week.  The two sets of figures correlate almost exactly and have done for the past ten years.

Amphibians are perfect indicators of environmental health as they are so sensitive to climatic change, particularly precipitation.  But you have to be careful of making an early assessment or reaching a conclusion too quickly as both weather conditions and population dynamics can differ from year to year.  To make any meaningful analysis you have to monitor over a long period of time to evaluate any trends.  I have been here at Bosque carrying out my research for 10 years.  Climate change is measured in 5 year averages.  So far I have two points on a graph, so a lot more monitoring is needed in the future to identify long term trends.

Right now all I can tell you is, the wetter it is, the more frogs there are.

Philip is a biologist, writer and photographer as well as the onsite naturalist guide at Bosque del Cabo Rainforest lodge on the Osa Peninsula, Costa Rica.

www.bosquedelcabo.com

Photo Feature

Over the course of the past two months there has been a collection of photographs in this particular feature that have depicted animals with eight, six and no legs, only frogs with four.  Tonight I am going back to six with some bugs and beetles that have posed for their portraits over the past year.  Neither bugs nor beetles are easy to identify simply due to the fact, once again, of the amazing diversity and a lack of adequate reference material.

Beetles are the most numerously named group of animals on the planet.  There are somewhere in the region of 270,000 named species of beetle worldwide.  Costa Rica has 47,000 named species of beetle.

Cicada

Cicadas are bugs, true bugs placed in the suborder Homoptera.  In the middle of January when it starts to become hot and dry, there will be a mass emergence of cicadas.  The nymphal stage of the cicada normally lives about two year under the ground.  They feed on the sap of trees, extracted by means of a long sharp proboscis, from underground roots.  One night when conditions are right and the evening air cools, the nymphs burrow out of the ground, climb the vegetation and split down the back.  The winged, reproductive adult emerges and flies up to the top of the trees.  In the morning the vegetation will be the site of many dry, empty nymphal skins all still clinging eerily to the underside of leaves like a scene from a science fiction alien body snatcher B-movie.

Head of Cicada - Close Up

During the course of the day as the temperature starts to rise, so does the sound of the cicada males calling from high up in the forest canopy for a mate.  The males have sound producing organs on the abdomen which vibrate to create the sound.  The hotter it gets, the more rapid the vibration until finally what was a low pitched hiss reaches a crescendo of high pitched whistle.  The adults only live about 4 – 6 weeks.  They mate and lay the eggs in the understory.  When the eggs hatch and the larvae emerge they fall to the ground and the cycle will bi-annual cycle will repeat.  The adults like the nymphs are sap feeders and are capable of piercing the tree bark to tap into the vascular system of the trunk.

Leaf-legged Bug

Leaf-legged Bugs are placed in the suborder Heteroptera.  They are plant feeders which, using the piercing “beak”, typical of Heteropterans, injects a digestive enzyme into the plant tissue then sucking out the resulting vegetable soup.  There does not appear to be a definitive answer as to why they have the expanded areas on the hind legs.  I would suggest a target for predators which may be left with only an insect leg, the rest of the bug having made its escape.

Long-horned Beetle

Long-horned Beetles are named after the very long antennae that may often be longer than the body length of the beetle itself.  Long-horned Beetle larvae are important decomposers of dead wood.  Male Long-horned Beetles can quite often by found during the day with their antennae extended attempting to pick up the pheromonal sex attractant released by the females.

The Lesser of Two Weevils

Weevils, of which there are over 7,500 named species in Costa Rica, are plant feeders. The front of the head is elongated into the typical “beak”.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Species List for the Day

Mammals

Howler Monkey

Spider Monkey

Agouti

White-nosed Coati

Birds

Red-lored Amazon

Scarlet Macaw

Bright-rumped Atilla

Southern Beardless Tyrranulet

White-tipped Dove

Blue-crowned Manakin

Chestnut-backed Antbirds

Black-hooded Antshrike

Fiery-billed Aracari

Chestnut-mandibled Toucan

Cherrie’s Tanager

Roadside Hawk

Black Vulture

Reptiles

Northern Cat-eyed Snake

Amphibians

Marine Toad

Red-eyed Green Treefrog

Banana Frog

Smokey Jungle Frog

Tink Frog

Fitzinger’s Rainfrog

Butterflies

Eueides aliphera

Heliconius ismenius

Hermeuptychia hermes

Morpho menelaus

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Posted September 22, 2010 by felipedelbosque in Philip's Nature Diary

One response to “Changing Bugs and Beetles

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  1. The lesser of two weevils……..ha ha!!! Sorry, small things amuse!

    Like

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