Wednesday, August 25, 2010

The predatory red assassin bug

The red assassin bug belongs to a large family of predatory insects which have an elongated head, narrowed neck and long legs. They also have a prominent tube which they use for sucking the liquidised contents of their prey. The family consists of about 7,000 species found in most parts of the world including Europe, North and South America and Africa. Twelve species are found in the Maltese islands. The red assassin bug, known in Maltese as seffud tal-assalt is the most common and easily recognised species.
This species can often be found waiting for its prey underneath the flowers of a number of summer-flowering plants especially fennel (busbies), samphire (xorbett) and fleabane (tulliera).
I photographed this specimen last Sunday at Fiddien Valley near Rabat. It had just caught a small bee as it was visiting the flowers of a sticky fleabane (tulliera komuni). The bug inserted its segmented proboscis in the space between the head and the thorax to inject it with a lethal toxin that dissolves its tissue. It then starts to suck up the liquefied tissues through its long proboscis. This process takes several minutes and so I had enough time to take several pictures of the bug as it was feeding.
Assassin bugs are aggressive insects and sometimes capture insects that are larger than themselves. They manage to subdue and kill them by means of their poisonous saliva. Some species of assassin bug feed on cockroaches or bedbugs. Some are beneficial to agriculture as they attack insect pests. In some parts of the world people breed assassin bugs as pets or for insect control.
Some species are notorious for biting humans and one species found mostly in South America can transmit the potentially fatal Chagas disease. (This article was published in The Times on 25.08.2010)

Wednesday, August 18, 2010

Butterflies need protection

Anthony Valletta was a keen lepidopterist. He spent most of his life collecting and studying butterflies and other insects and was one of the first people in Malta to talk and write about the need to protect Malta’s natural environment. He wrote a number of books for children and adults as well as articles in newspapers and magazines.

In 1980 he wrote an article about the butterflies of the Maltese islands and their dwindling habitats, in which he expressed concern about an alarming decrease in the number of individuals of certain butterflies which he was noticing. He wrote that complete colonies had disappeared from newly built up areas. He noted that in the 48 years during which he had been studying butterflies the colourful abundance of these beautiful insects had become a thing of the past. As is the situation today the most common butterflies were the migrants who every year augmented the local population.

Lately I have been talking a lot with Maltese farmers especially elderly ones who remember the countryside as it was sixty or seventy years ago and what all of them told me sadly reflects what Valletta wrote thirty years ago. Mr Valletta believed that the decline was being caused by the destruction of the butterflies’ habitats because of new residential areas. He also blamed the planting of ornamental trees along the sides of valleys which were replacing local flora. The farmers blame the large quantities of pesticides that they use for the decline.

I am not aware of any studies that have been carried out to monitor the butterfly decline and their causes. It is already late to save the butterflies but it is better late than never and we can if we want to, halt the decline and even to reverse the trend. We owe the butterflies to future generations of Maltese people. We also have a responsibility to conserve local races such as that of the swallowtail butterfly which is endemic to the Maltese islands.

Mr Valletta wrote that many of the natural habitats would continue to disappear but he hoped that those in a position to do so will encourage the preservation of all existing species by ensuring that the necessary food plants are not entirely eradicated from the countryside and in some cases that these would be deliberately propagated.

Unfortunately, many species that Mr Valletta once enjoyed have become a rarity and might soon become extinct from the Maltese islands unless urgent action is taken to save them.

This article was published in The Times on 18.August.2010)

Saturday, August 14, 2010

The ecological importance of Il-Maqluba

Il-Maqluba is a site of natural and geological interest on the outskirts of the small village of Qrendi. It is a circular crater known as a sink hole that was formed when the roof of a large underground cave collapsed. 

It is believed that this happened in November of 1343. In geological terms this is a very recent event and no major changes have taken place since the event occurred. Given that caves are common in the Maltese island it is not surprising to find such a structure and in fact other similar structures of varying ages can be found. 

Sink holes slowly fill up with sediment that is blown or washed into it and eventually it fills up completely to form a soil-filled depression. Such a structure is found near St Martin’s Church at Baħrija and it is now a very good area for agriculture. Along the west coast of Gozo one can also find similar structures one of which is known as the Inland Sea.

Caves form when acidic rain water flows through hollows and fissures dissolving the rock and creating tunnels which eventually, as a result of more and more water flowing through them, widen and enlarge and eventually become caves.

The best known cave is Għar Dalam near Birżebbuġia which when excavated yielded thousands of fossilised bones and teeth of long extinct animals including dwarf elephants, hippopotamus and deer.

Il-Maqluba is important ecologically because in it one can find several interesting species of plants and animals which thrive in it because of its inaccessibility. Amongst these one finds several large specimens of Malta’s national tree - the sandarac gum trees (għargħar) which grow on the cliff sides. 

Until about a couple of decade ago it was believed that these were the only specimens of this tree, which is a native of North Africa, which were still growing wild in the Maltese islands. The site is also important because on its walls one can find a population of the Maltese salt-tree (xebb). A species of slug which is endemic to the Maltese islands was found in the depression together with other species of rare animals including ants and a silverfish.

It is not surprising that such an unusual structure needed an explanation that could be understood by the local people. They thus came up with the story that in ancient times at Il-Maqluba there was a small village inhabited by evil people. 

One day the land collapsed and the whole village was swallowed by the land. All the inhabitants died except for a pious lady who was praying in the small chapel next to the village. In fact there is an old chapel dedicated to St Mathew still standing next to the depression. 

This article was published in The Times on 10.02.2010

The common fresia - a member of South Africa's iris family

The freesia is another non-indigenous species that was cultivated in Maltese gardens that now grows in the Maltese countryside. It is a South African member of the iris family. There are about 16 species of freesias. 

Fourteen are native to the Cape Province in South Africa and two are found in tropical Africa as far north as Sudan. The genus was named after Friedrich Heinrich Theodor Freese, a German physician who lived between 1795 and 1876.

The common freesia, which is known in Maltese as freżja, has grassy foliage, and wiry spikes of bell-like, lemon-scented flowers in white, yellow, orange and blue. A few decades ago only white-coloured freesias were cultivated but nowadays many other varieties and hybrids can be found in flower and gardening shops. These usually are larger than the old variety and come in an incredible variety of colours. 

Due to their specific and pleasing scent, they are often used in the manufacture of hand creams, shampoos and candles.

In Malta the common freesia can be found growing in such places as Buskett Gardens and the grounds of Verdala Palace. It manages to grow wild because parts of South Africa, where this species comes from, like the Maltese islands has a Mediterranean climate. 

This climate is characterised by warm to hot, dry summers and mild, wet winters. South Africa is not the only part of the world with a similar climate to ours. This climatic type is also found in much of California, in parts of Western and South Australia, and in parts of central Chile.

Freesias are used as a food plant by the larvae of some moth species including the large yellow underwing, known in Maltese as baħrija safra kbira. This is a very common species of moth found throughout most of Europe and North Africa extending east all the way to India. It can be seen between March and May and again between August and November. 

This article was published in The Times on 17.02.2010

Thursday, August 12, 2010

The fig tree

Country people used to say that the cicada appears when the fruit of the fig starts to ripen while others even claimed that the cicada actually ripens them. The adult cicada lives for a few summer weeks while the fig survives for many years and can grow into a large spreading tree that can produce large quantities of good tasting fruit every year.
The fig tree is an indigenous tree native to Southwest Asia and the Mediterranean. It has been cultivated in the Maltese islands for centuries and often grows wild in the most improbable of places. The large lobed leaves are easily recognised as they have been used for by artists to cover the genitals of nude figures. In the Book of Genesis Adam and Eve covered themselves with fig leaves after eating the forbidden fruit.
The fig tree, known in Maltese as siġra tat-tin was one of the first plants to be cultivated. Remains which were found in a Neolithic village in Jordan were dated to 9,400 to 9,200 BC. It was domesticated before wheat, barley and rye. Its fruit known in Maltese as tin is eaten raw, cooked, or dried. Once harvested the fruit does not keep well and should be eaten with the least possible delay unless it is to be preserved. Cato a Roman statesman urged the Romans to destroy Carthage and showed the Senate a handful of fresh figs from Carthage to show its proximity to Rome and hence the threat.
In the millennia that this species has been cultivated many varieties and cultivars have been developed. These vary in many ways including in the colour of the skin can be green purple or brown. When a branch, leave or fruit is broken off the tree releases a white sap which is an irritant to human skin. In the past the sap was sometimes used to reduce the pain and swelling of a bee or wasp sting.
Figs are one of the highest plant sources of calcium and fibre. Dried figs are rich in fibre, copper, manganese, magnesium, potassium, calcium, and vitamin K and have smaller amounts of many other nutrients. Figs are used as a laxative and contain many antioxidants. (This article was published in The Times 12.08.2010)

Saturday, August 7, 2010

Poppies - long used as a symbol of sleep and death

Poppies are among the most common spring flowers in Malta. The most familiar is the common poppy which grows in very large numbers in cultivated fields but one should take up the challenge and try to spot the other species which also thrive in the Maltese islands. 

At least five other less familiar but still common species of poppy can be found without difficulty if one looks carefully at the flowers growing in fields and along country paths at this time of the year.

The opium poppy (xaħxieħ vjola) has large violet flowers and is easily identified. Less showy but just as interesting is the bristly poppy (peprin tal-lanżit) which has claret flowers and bristly fruit. The other two common species are the long-headed poppy (pepprin tal-frotta twila) and the Mediterranean poppy (pepprin tal-istammi sofor). Another species is the yellow horned poppy (pepprin isfar) which flowers later in spring on disturbed land close to the coast.

Most poppy species have been grown in gardens and some are used for both drugs and food. The opium poppy is cultivated in large quantities for opium and opiates as well as for poppy seed which is used in cooking and baking and poppy seed oil. Poppies have long been used as a symbol of sleep and death because of the opium extracted from them and the red colour. 

In some cultures they are used as emblems in tombstones to symbolize eternal sleep and resurrection.

The poppies are just a handful of the large number of flowering plants that one can find in the Maltese countryside. Over one thousand species of flowering flowers have been recorded. 

This article was publishen in the Times on 07.04.10

Bees - 20,000 known species worldwide

Malta is justifiably well known for its honey. This natural product is produced by a domesticated species of bee. Although this is the best known species it is just one of at least 60 bee species that have been recorded in the Maltese islands.

Bees are flying insects closely related to wasps and ants. They are known for their role in pollination. 

There are nearly 20,000 known species of bees in the world with several still to be discovered. They are found in every continent except Antarctica and in every habitat where one finds insect-pollinated flowering plants. They are adapted for feeding on nectar and pollen which provide them with their energy and protein requirements. Pollen is used as food for larvae.

Bees play an important role in the pollination of flowering plants. When foraging they either gather nectar or pollen. While doing this they carry pollen from one flower to the other. Pollen is fine powder which contains the male sex cells of a plant. When the pollen reaches the female sex cells of a plant, a process known as pollination, fertilisation takes place. It is estimated that one third of the food consumed by man depends on insect pollination, mostly by bees especially the domesticated honey bee.

Most bees are fuzzy and have an electrostatic charge which attracts the pollen. The bees occasionally brush the pollen attached to their body and pack it into a structure that is usually found on their legs but sometimes on their abdomen. 

Some species of bees specialise on one species or a small number of related species of plants while others are opportunistic feeders and gather pollen from a large variety of plants.

Bees evolved from predatory wasps. When they first appeared there were already in existence insect pollinated plants which depended on other species of insects such as beetles for pollination but they have now become specialised pollinating agents much better at it than other insects such as flies and butterflies. 

This article was published in the Times on 23.02.10

Wednesday, August 4, 2010

A genus of nocturnal moths

Dysgonia is a genus of moths. Two members of this genus can be found in the Maltese islands. 

The two species resemble each other and can be difficult to tell apart. They do not have common English names and as happens in such cases it is better to refer to them using their scientific names. Dysgonia algira has been called baħrija tar-riġnu in Maltese while the Dysgonia torrida is called baħrija tar-riġnu Afrikana

Both species can be found between June and October. The caterpillar of both species feed on bramble, willow trees, castor oil tree and pomegranate. The moth in the picture was photographed at Fiddien a couple of metres away from a willow tree on which I assume its caterpillar was living. 

Dysgonia algira is found around the Mediterranean, in Asia Minor, Syria and Mesopotamia. Dysgonia torrida is found in Spain, Portugal, Sicily, Italy, Greece, Morocco, Egypt, Asia Minor and India.

The genus Dysgonia belongs to the family Noctuidae which is sometimes referred to as the owlet moths. This is a large family of mostly drab-coloured moths, although some have brightly coloured hindwings. The family has more that 35,000 known species. About 1,450 are found in Europe of which about 135 species are found in the Maltese islands.

Most of these species are nocturnal and are often attracted to lights as well as to sugar and nectar-rich flowers. Many are able to avoid bats as they have organs in their ears which are stimulated by the echolocation sounds made by bats. This causes their wing muscles to go into spasms and the moths start to fly erratically thus evading the bats.

Several species have caterpillars that live in the soil and are agricultural pests. These often feed at night and during the day they rest in the soil or in a crevice in its food plant. 

This article was published in The Times on 27.07.10

The invasive cockroaches

I do not think that there is any household in the Maltese islands that at some time or the other has not had cockroaches visiting the kitchen. These insect pests are scavengers that eat any food and manage to find something edible even in the cleanest of homes.

There are about 4,500 species of cockroach, of which about seven species are found in the Maltese islands. Four can be found in houses and unless controlled can become pests.

The large brown cockroach one sometimes sees scurrying in the street is the American cockroach which did not originate in America but came from Africa. It was introduced in America around 1625 and is now common in most tropical countries thanks to international shipping and commerce. It feeds on decaying organic matter and a variety of other foods and is particularly fond of fermenting foods. It is known in Maltese as wirdiena ħamra.

Another common species is the brown banded cockroach which is known as kokroċ in Maltese. The preferred habitat of this species is houses especially kitchens. It is much smaller but can reach large numbers if it finds the right conditions.

Some species such as the field cockroach which is known in Maltese as wirdiena ta’ l-għelieqi, live in the countryside and do not visit buildings.

Cockroaches are mainly warmth-loving insects. Some species thrive in buildings because these provide warmth and food throughout most of the year. They are known to transport microbes on their body surfaces including those that are potentially dangerous to humans. They also produce chemicals which can trigger allergic reactions and have been linked to asthma

Cockroaches are tough creatures that can survive in the most difficult conditions. They can live without food or water for a very long time. Some species can survive without air for up to 45 minutes and have been submerged in water for half an hour and survived to live another day. It is also said that if man had to destroy himself with a nuclear war the cockroaches would survive and take over the earth. 

This article was published in The Times on 04.08.2010