invertebrate & other shelters · these “shelters” are sophisticated hunting traps, in the form...

– African Tracks and Signs Course by Chris & Mathilde Stuart

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Invertebrate & Other Shelters © Chris & Mathilde Stuart

Module # 10 – Component # 4

Invertebrate & Other Shelters

Invertebrate shelters

Some of the most complex shelters are constructed by termites, ants, bees and wasps.

Many species are highly social and their societies and shelters function in much the

same way as human settlements. Although in most cases the intricate structures are

hidden from our view it is often possible to identify the group of insects or other

invertebrates responsible for them.

Virtually throughout Africa the most visible and regularly seen shelters are those

constructed by termites (incorrectly called white ants by many people). They are to

be found in most habitats and take many forms, from very little surface signs to mighty

castles of clay.

Ants also have complex social systems, but many species live in colonies well hidden

from sight: deep underground, under rocks or logs or among dense vegetation. There

are however a number of notable exceptions.

The wasps are among the most accomplished insect architects; some build brood

chambers from mud, others from chewed plant fibres, some construct underground

chambers with elaborate mud entrance tunnels. Many wasps are solitary, others live

in small colonies.

Bees, particularly the honey bees, usually have well-hidden hives, either underground,

in deep rock crevices, in holes in trees or in other cavities. There are a number of solitary

species.

Other invertebrates that construct well-known shelters are the spiders. In many cases

these “shelters” are sophisticated hunting traps, in the form of the silken webs which

the spiders spin to ensnare their insect prey.




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The harvester termites (Hodotermes spp.) create loose mounds of earth pellets that

are rarely higher than a few centimetres. Another characteristic of this group is the

small piles of cut grass stems and leaves surrounding entrance holes. The darker

patches in the photograph consist of freshly excavated soil.




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The mounds of the snouted harvester termites (Trinovertermes spp.) are a common

feature of the African landscape, particularly savanna. Most mounds are 50 cm high,

but some may reach 100 cm. Similar mounds (about 35 cm high) are constructed by

the black mound termites but as their name implies there “castles of clay” are usually

black. These termites eat humus and wood.




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A snouted harvester termite mound showing the dark, freshly added soil-saliva mixture.

This soon dries and lightens in colour.




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Snouted harvester termites adding to the mound; most building takes place in the rainy

season.




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An abandoned and weathered termite mound, revealing the internal passages.

Abandoned mounds weather slowly and may last many years.




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Some of the fungus-growing termites (for example Macrotermes spp.) construct very

large surface mounds that are a common feature of Africa. The mounds may be tall

and pointed as in the photograph, or huge and rounded. Odontotermes species are

also fungus growers.




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Some termites, including the fungus growers (Odontotermes spp.) construct ventilation

shafts to control the temperature in their underground “cities”. These shafts are used

as shelter by many vertebrate and invertebrate species, such as this skink.




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A mound with several ventilation shafts, created by fungus-growing termites. This type

is common in Kenya.




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In the forests of tropical Africa, the termite Cubitermes speciosus constructs a unique

mound that resembles a multi capped mushroom, with up to five caps. These act as

umbrellas to deflect the copious rains that fall in these areas.




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In the African tropics a number of termite species construct their clay citadels in trees.

These are usually found in areas of high rainfall and where the ground gets quickly

water logged. Note the “tassles” on the undersurface of the nest which serve to allow

efficient water runoff.

Termite “fields” are common across the African tropics and may involve a single or

several species.




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A tree-dwelling termite colony in eastern Tanzania. The extensions at the bottom of the

"nest" allow water to run easily off during the rains.




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Termite mounds in a dambo in north-eastern Zambia. These grass gathering termites

can occur at amazing densities and are a common feature of seasonally flooded

grasslands.

Snouted termite mounds in a grassland pasture near Bedford in the Eastern Cape,

South Africa. These grass harvesters and their mounds compete strongly with domestic

livestock. If you look closely the dark spots on some mounds indicate where aardvark

have opened mounds with the powerful front claws to feed on the termites and their

larvae, drawing them out with the long, sticky tongue.




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Termite ventilation shafts come in a great many different forms. This in Mkomazi,

northern Tanzania, has three tall ventilation shafts that are open at the top and allow

air circulation in the colony.




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An umbrella termite mound in Katavi, western Tanzania, is constructed in this way to

deflect heavy rainfall to prevent erosion of the mound.




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The entrance holes and debris excavated by harvester ants, with inedible seed husks

and other plant material. Note the distinct foraging trails radiating from the colony.

The mound in the background was constructed by snouted harvester termites.

Harvester ants bring out seeds to dry in the sun before returning them to underground

storage chambers.




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Another example of harvester ant colony with large quantity of seeds laid out to dry.




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These large Camponotus sp. ants are living in a hole at the base of a snouted termite

mound.




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A number of ant species pile debris from their underground colonies around the

entrance holes; this is the work of a Camponotus ant colony photographed in the

Kalahari.




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Rings of excavated soil on the surface of a colony of the brown house ant (Pheidole

sp.).




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A tailor ant colony in Shimba Hills, Kenya. The intricate nest is constructed with leaves

bound together with "webbing" secreted by the ants. If a nest is disturbed the ants

react immediately and aggressively.




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Cocktail ant nest colony in a young fever tree KwaZulu-Natal, South Africa. The nests

of this group of ants is found widely and are constructed with pulped plant material.




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The nests in the following 2 photographs had been constructed by paper wasps

(Belonogaster spp.). The larvae, each in an individual cell, are fed on chewed

caterpillars or other insects by the females. Nests are commonly built in buildings, in

trees and bushes or hanging from rocks. The wasps are very aggressive when disturbed

and can deliver an excruciating sting. The cells that are closed contain pupating

young.




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The multi-chambered nest of a Sceliphron sp. wasp; these nests may reach lengths of

as much as 20 cm. Each chamber is packed with paralysed spiders and one egg is

laid in each chamber. These mud nests are commonly found in buildings, on rocks and

in trees throughout Africa.




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An entrance tube to the nest of a mason wasp (Odynerus sp.); note the wet ring of

fresh mud being added to the mouth of the tube by the wasp. These wasps’ stock

their nests with paralysed caterpillars.




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Non-turret brood chambers of Mud Dauber (Sceliphron spirifex) wasps; tube-like turrets

of Tricarinodynerus wasps. The brood chambers of these two-wasp species were

constructed in the broken nest of a South African cliff swallow. There are many wasp

species that construct nest chambers from mud.

Video: Mud dauber wasp building brood chamber.




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One of the most frequently encountered insect shelters in many drier parts of Africa is

the conical pit constructed by the larva of the antlion (Family Myrmeleontidae). The

pits are usually about 3 cm in diameter at the top, steep-sided and 2 - 3 cm deep. A

single large-jawed larva remains buried under the pit, waiting for an unsuspecting

insect to fall into it, where it is promptly seized and eaten. Pits are usually found in

groups, with larva trails meandering over the area.




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The shelters constructed by two marine crabs (Crustaceae) warrant mention as they

are abundant and obvious: The ghost crabs (Ocypode spp.) are common on sandy

beaches, particularly in the African tropics, and they construct burrows that are

distinguished by the numerous tracks around the entrance. Burrows are located near

the high-water mark and there may be many close together.




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The red mangrove crab (Sesarma sp.) excavates a hooded burrow, which is one of

the most frequent shelters found in mangrove swamps. Note the pellets of excavated

mud and the slight overhang over the entrance. The entrances are up to 12 cm in

diameter.




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Another skilful builder is the larva of the bagworm moths (Psychidae), which are

widespread in Africa. The larva may build a “mobile home” of cut twig segments, small

stones, sand grains, pieces of leaves and small shells.




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A web constructed and occupied by communal-living spiders (Family Eresidae).

These large webs are a common sight.




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Another communal-spider web. It should be noted that the caterpillars of some moths

spin communal webs over their food plants.




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A typical spider web covered in dew droplets.




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A web spun by a kite spider (Gasteracantha sp.) across a forest path.




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A large female orb spider showing the golden-coloured thread that typifies the webs

of golden orb spiders.




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The brood chamber of a garden, or rain, spider in the Western Cape, South Africa.

Leaves are bound together with webbing and in their centre the female lays her eggs.




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The large, multi-layered web of a tropical tent-spider (Cyrtophora sp.).




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The entrance to this baboon spider tunnel was 3,5 cm in diameter. The shelters of some

species do not extend beyond the surface.




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A Palystes sp. spider defending her egg sac. This nest was made of web silk and no

plant material was included. The females of these spiders remain close to the nests

and defend them vigorously. The egg sacs are usually quite large, many exceeding 8

cm in length.




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The retreat of a funnel-web spider. There are many species, each with its distinctive

web form. This individual had taken over a hole excavated by a woodborer beetle.




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The retreats of one of the rock rain spiders (Olios spp.); these are of tough webbing

and are usually located under rocks.




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Praying mantis (Order Mantodea) females about to lay eggs secrete a gum-like liquid

that has a consistency like silk. On contact with the air it turns into foam and she moulds

it into shape (which varies according to species), laying the eggs in the centre, each

in its own chamber. The foam hardens and is remarkably tough. The nests are usually

attached to vegetation or rocks. These two praying mantis egg-cases were 7 cm and

8 cm long, but many are much smaller.




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Other shelters

Amphibians

A foam nest of over 10 cm is constructed by the grey tree frog (also known as the

foam-nest tree frog). The female secretes a substance which she and attendant males

beat into a foam with the hind legs and feet. It has the appearance of whipped cream

and produces a safe, moist nest for the eggs and the early tadpole stages. These nests,

attached to branches or other vegetation above water, are produced during the rains.

They are a common sight in the tropics and subtropics.




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A fresh grey tree frog foam-nest. The tadpoles drop from the nest to the water below.




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Reptiles

Many lizard species live in holes in the ground but most use those dug by other

animals, such as rodents. The barking geckoes (Ptenopus spp.) live in loose, sometimes

large, colonies, each excavating its own burrow. The entrances are oval, roughly 2 cm

wide and 1 cm high. Burrows are most commonly in sandy flats, such as riverbeds, in

the arid west of southern Africa.




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Burrow of a barking gecko compare this with the burrow of a scorpion.

invertebrate & other shelters · these “shelters” are sophisticated hunting traps, in the form...

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