December 2019

Milkweed bugs with
young nymphs
Sheila Sims

The Ecuadorean cloud forests are home to many insects, some of which are still to be identified. All over the world those insects which are brightly coloured have evolved, by natural selection, to be like this either to attract a mate or more usually to give a message to predators that they are not good to eat, maybe even toxic. One of the latter that inhabits Ecuador and other new world countries, is the black and orange Milkweed bug. This insect, like all bugs, does not have mouth parts like beetles that enable them to bite and chew their food, but has a piercing tube, a proboscis, for sucking the sap from plant stems, leaves and seeds; Milkweed bugs, as the name suggests, feed mainly on the seeds of the Milkweed plant. This is a poisonous plant and insects that feed on it accumulate the toxin in their bodies. (The Monarch butterfly caterpillars, which also feed on this, have brightly coloured stripes which act as a warning to anything that might fancy them as a snack.) The young nymphs of the Milkweed bug grow out of their skins and will moult them several times before they achieve maturity.

Falcate heliconia
Sheila Sims

Another Ecuadorean insect that relies on its bright colours to warn off potential predators is the Falcate heliconia butterfly. The larvae of this beautiful creature feed on leaves which contain a cyanide-like compound. Like many caterpillars that eat poisonous plants they are able to render the toxin harmless to themselves but it persists in the adult butterfly, hence the warning colours; the pollen that the Falcate heliconia feeds on helps to activate the toxin. Many insects and spiders have other ways of preventing predation. They have evolved to look like the surrounding habitat and as in this country, which we have talked about before, some Ecuadorean forest creatures do the same; this happens all over the world. Some look like plants, fungi or lichen and some imitate other creatures that are dangerous. To evolve to be like this must have taken centuries of natural selection unless, as with our own peppered moth, something happened to speed up the process; the Industrial Revolution in the case of the moth. ( See August 2017.)

Scarab beetle
Sheila Sims

We also came across Scarab beetles of which there are many types in the world. Scarabs were considered sacred in ancient Egypt because those that rolled dung into balls and pushed them along were likened to the sun god Ra who rolled the sun across the sky every day. (They had good imaginations, those ancient Egyptians!) However, the ones we saw in Ecuador were certainly not revered! Like moths many are nocturnal and are attracted to lights in buildings which, if you don’t like beetles buzzing around the dining room, can make them a bit of a nuisance. Scarabs’ diets vary, depending on the species. Some feed on plants which sometimes makes them serious agricultural pests, some are nectar or pollen feeders and others eat rotting organic material. The female lays her eggs in the soil close to a food source, or in a dung ball, and the hatching grubs often become dinner for birds or mammals.

Geometer moth
Sheila Sims

At the forest lodge they had a moth trap. Nothing that harmed the moths or even trapped them but just a bright light and a white sheet. The nocturnal moths were attracted to the light and settled on the sheet where many of them remained during the daylight hours. One that was particularly attractive was a member of the Geometer family which has relatives which live all over the world. Geometer means ‘earth measurer’ and refers to the caterpillars, sometimes called inchworms or loopers, which, because they only have legs at each end of their bodies and none in the middle, move in a looping fashion as though they are making measurements. If one should feel threatened it stands erect hoping that whatever wants to eat it will be fooled into thinking it is a twig. Because the caterpillars feed on the leaves of various trees and shrubs, some species of Geometer moths do a lot of damage and are considered pests.

Black-eyed Susan vine
Sheila Sims

Cloud forests have many beautiful plants, some which people are surprised to recognise, known to us as house or garden plants. We often struggle to grow these because of our climate but in their native habitat they grow profusely. One that we will all be familiar with is the Black-eyed Susan vine which climbs through the Ecuadorean forests as though it owns them! Another prolific flowering plant is the Ecuador princess which is often grown as a garden plant in the warmer parts of the USA.

Ecuador princess
Sheila Sims

Bromeliad
Sheila Sims

Bromeliads grow on the trees of the forest but they are not parasitic and don’t use the trees to obtain nourishment but purely as supports and to get closer to sunlight. Bromeliads often have leaves that form coloured rosettes, which trap water and debris and attract insects. This provides the plant with its food and also tiny frogs with a place to lay their eggs. The hatching tadpoles will often spend their juvenile life in these little pools until they mature into adult frogs, when they will disperse into the forest.

Other kinds of Bromeliads are known as Airplants because they obtain everything they need to survive from the air. Moisture from clouds, rain and mist is absorbed through their leaves and these also grow on trees. Many will grow on rocks or anything that will act as a support; I have seen these, in the Caribbean, growing on telegraph wires! Some types of orchids also grow on the forest trees and prefer the rough barked ones. The bark will trap water and debris which feeds the plant but they also obtain moisture from the air.

An interesting and adaptable group of plants which have evolved to take advantage of their forest habitat.

Next month we will be back in the forest and visit a couple of farms – one quite unusual!

© Sheila Sims 2019. Email: sheila@norfolknaturediary.uk

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