Beetle mania

Recently while taking some early morning pictures at Fiddien I found a species of black beetle that I had never seen before. A friend of mine, a specialist in beetles, identified it for me.

It was a nocturnal weevil known to entomologists as Otiorhynchus lugens but for which I could not find a common name.

Weevils are recognised by their long snout and small antennae which have small knobs at the end. They are plant feeders and are often found on or near their food plant.

The weevil family is very large. Over 40,000 species have been identified worldwide of which more than 120 species, including several endemics, are found in the Maltese islands.Most of the weevils I am familiar with are either a shade of brown or grey.

Being black and nocturnal this species made me think about the fact that although the most familiar beetles such as ladybirds and leaf beetles are brightly coloured, many beetles, many of which we do not often see, are black.

A study carried out about ten years ago in Brazil found that the body colour of beetles is strongly related to their daily activity pattern. In other words, nocturnal beetles are likely to be black while diurnal species are either brown or brightly coloured.

Bright colours are used to warn predators, especially birds, that that particular insect is either bad tasting, poisonous or that it can inflict a painful sting. Brown or grey colours camouflage them, making them difficult to see against their surroundings. On the other any brown or grey beetle would be easy to spot in the darkness so nocturnal beetles have evolved black bodies which makes them difficult to see at night.

This gives them an advantage over beetles that are not black, as, being more difficult to see there is a smaller chance that they are eaten by predators.

This article was published in The Times on 28.12.11

Of seeds with ‘papery wings’

The sandarac is Malta’s national tree. It was presumably chosen because of its rarity in the Maltese islands. 

Its main range is in the Atlas Mountains of Morocco, Algeria and Tunisia. Outside North West Africa it is found only in Malta and Cartagena in southeast Spain.

It is a conifer and like all conifers the seeds are produced in cones. 

In this species the cones are between ten and fifteen millimetres long. When young they are green, turning brown as they age. 

They consist of four thick scales arranged in pairs to form an uneven sphere. When the cones open, the seeds which have papery wings float gently to the ground.

In Maltese the sandarac is known as għargħar, a semitic name that indicates that this tree was already present when the when the islands were occupied by the Arabs. 

Up to about thirty years ago it was thought that this tree grew only at Maqluba, near Qrendi, but a small grove was found near Mellieħa. 

In the past this tree was said to have been much more common especially in the area around Birkirkara and around the village of Għargħur.

It is a tree adapted to the hot dry summers of the Mediterranean. It can survive burning and can re-grow from cut or burnt stumps. Trees that have been burnt repeatedly over a long period of time form burrs known as lupias. 

Burrs are stress-induced deformations usually in the form of rounded outgrowths of the trunk. Burrs are usually highly prized and sought by furniture makers and artists. To obtain the lupias the sandarac trees are destroyed and this has led to large parts of Morocco being deforested.

The tree produces a resin which is used to make a varnish which was used to protect paintings and antiques. For many centuries sandarac was the only varnish in use until it was replaced by cheaper varnishes. 

In parts of North Africa the resin is traditionally used to make a liquor and as a remedy in cases of difficult childbirth as well as to reduce cramps. Sandarac is burned to treat colds or taken internally to treat roundworms and tapeworms.

The wood of the sandarac is known as citron. In Romans times it was often used in house building and is still used in cabinetry and to make decorative objects. 

This article was published in The Times on 21.12.11.

Fly that pretends to buzz like a bee

Hoverflies, as their name suggests, are well known for their habit of hovering in front of flowers. 

Many adult hoverflies feed on nectar and pollen while the larvae feed on a variety of animal and plant material. 

In some species the larvae are insectivores. These are now being used to control plant-sucking insects such as aphids which can cause widespread damage to agricultural crops.

Hoverflies are found on all continents except Antarctica. 

At least six thousand species have been identified and named of these about 30 species have been recorded in Malta but I would not be surprised if more species are discovered in the future.

Hoverflies rely on mimicry to protect themselves from predators. 

They resemble dangerous insects especially bees and wasps and even hover and buzz like them. Their mimicry is so good that predators mistake them for dangerous insects and leave them alone even though they are not dangerous as they do not sting. 

Hoverflies are so confident of their mimicry that unlike most other insects they do not fly away when approached and one can get many opportunities to get good close up pictures of them. 

Pictures can be useful when trying to identify this group of insects as unless one is a specialist it can be very difficult to tell species apart in the field.

Many species of hoverflies can be seen on flowers on warm spring days but even at this time of the year one can observe a number of species feeding on pollen produced by autumn and early winter flowering plants such as the daisies which are already in flower. 

Common species in Malta include the drone-fly (dubbiena dakar), the lesser drone-fly (dubbiena ta’ l-għajnejn irrigati), the common yellow-banded hoverfly (dubbiena żunżanija) and the slender hover-fly (dubbiena tal-fjuri). 

This article was published in The Times on 14.12.2011

The shell that lets in light

I spent an enjoyable afternoon last Sunday taking pictures of sea snails and shells washed ashore during the recent stormy weather.

I found several interesting species which are normally associated with a sandy sea bottom.

The Maltese islands do not have regular tides, but the sea level sometimes goes down by a few centimetres, which in places like Għadira Bay can result in a considerable retreat comparable to a tide.

When this happens one gets the chance to observe more specimens of marine flora and fauna.

The most common seashell on the beach was that of the rayed trough-shell (Mactra stultorum), which is known in Maltese as arzella tal-baħar.

This species belongs to a family of bivalve molluscs commonly known as trough shells or duck clams.

Ten members of this family are found in the Mediterranean but only four species have been recorded around the Maltese islands.

The rayed trough-shell is found in the north, from Norway down the west coast of Europe to the Iberian Peninsula and along the African coasts as far south as Senegal. It is also found along the Mediterranean and Black Sea coasts.

It lives in sandy bottoms from five to 30 metres deep and is often found cast up on beaches. It has a thin and delicate shell through which light can pass, providing one with many opportunities to create beautiful pictures especially early in the morning or late afternoon.

Like many other species of molluscs, the rayed trough-shell is edible and in some places it is collected and sold in markets.

This article was published in The Times on 7.12.11

The healing field marigold

The field marigold is a member of the daisy family. It is native to central and southern Europe including the Maltese islands. 

It has now been introduced in many countries throughout the world in some of places it is considered as a pest. 

In Malta we find two subspecies of field marigold one of which even exists in two varieties. 

This makes identification of this species somewhat confusing a situation which is not made any easier by the fact that the daisy family which is made up of over 20,000 species is the largest plant family. In Malta the daisy family is represented by about 120 species.

The two races of field marigold are known in Maltese as suffejra tar-raba’ and suffejra kbira tar-raba’. The variety being shown in the picture has been named suffejra tar-raba’ ta’ ġiex kuluri.

The field marigold is widely cultivated as a garden plant but it is better known for its medicinal properties. 

It is said to have antibacterial and anti-inflammatory properties and has been used extensively to heal wounds. It is believed that its anti-bacterial properties are partially a result of the structure of its sugar which stimulates the body’s immune system. 

To heal minor wounds the leaves and petals can be ground or crushed into a paste, mixed with water and applied to the wounds. The flowers have also been used to treat stomach ulcers and gastrointestinal problems for hundreds of years.

Plant identification is an interesting and sometimes challenging task. Until the invention of modern pharmaceuticals most people interested in plants were pharmacists and doctors who studied botany because many plants were used for medical purposes. 

Botanists today still study plants because of their medicinal value but a growing number of enthusiasts are taking an interest in wild plants as a hobby. 

This article was written in The Times on 30.11.11

The leaf beetle family

Chrysolina variolosa

Leaf beetles are members of an insect family represented  by about sixty species in Malta. 

The one pictured with this article is known simply as a leaf beetle and in Maltese as żabbella a name that was used also for the ladybirds. The scientific name which distinguishes this beetle from all other leaf beetles is Chrysolina variolosa.

This species is frequent although not common. 

It is usually found on the spiny asparagus, (spraġġ in Maltese) as it probably eats its leaves.

But the specimen I photographed last Sunday at Mistra Bay was walking on rocks far from any asparagus plant.

The leaf beetle family is the largest and most commonly encountered beetle family. It is estimated that there are over 35,000 species in this family. Several species are of economic importance because of their impact on agricultural produce. 

Some have been used to control weeds biologically especially in Australia and in California.

But the greatest impact is probably that of another species - the Colorado potato beetle which can devastate entire crops of potato.

The Colorado potato beetle is indigenous to the Americas but it was not until 1840 that it started to become a pest of the potato plant. 

It appeared in Germany in Germany in 1877 but was soon eradicated from there. It reappeared in Europe sometime during World War I. It was first observed near American military bases in Bordeaux and from there it spread to Belgium, the Netherlands and Spain eating its way through potato fields.

Soon after the Colorado potato beetle started to spread in Europe the Maltese Government, prohibited the importation of crops from any areas where this beetle was present and managed to keep the Maltese islands free from this pest.

In 2008 the European Union issued a Directive by means of which Malta was declared a protected zone and was thus given special protection to be able to take measures such as plant quarantine to keep the Colorado potato beetle away from the islands. 

This article was published in The Times on 23.11.11)

Of gourd ladybirds and the squirting cucumbers

Many species of animals and plants are closely linked together. In some cases the relationship benefits one species only and in others both species benefit from the relationship. 

This relationship often means that if one species had to disappear the other would not be able to survive on its own and would cease to exist as well. 

One such relationship is that existing between the squirting cucumber (faqqus il-ħmir) and the gourd ladybird (nannakola tal-faqus il-ħmir).

The squirting cucumber is a common plant with large leaves and yellow flowers. The fruit are oval and when ripe they shoot out the seeds. The seeds emerge with such force that they can land up to one metre away from the parent plant thus helping the plant to disperse. 

The squirting cucumber grows in disturbed habitats along country lanes and in urban areas.

Whenever you find a squirting cucumber you are also likely to find the gourd ladybird. This species of ladybird spends its entire life on the squirting cucumber. Ladybirds are known to be predators. 

Most feed on insects especially aphids but I have never seen this species eating other insects. I have often seen the adults in the flower of the squirting cucumber probably eating pollen. 

Adult ladybirds often carry a sprinkling of pollen on their wings which indicates that they could be transferring pollen from one flower to another thus aiding pollination.

The eggs are laid on the plant and the larvae spend their entire life on it. I have not found any literature on the life cycle of this species but I have seen small parts of the surface of the leaf on which a larva of this ladybird is living eaten away which indicates that the larvae feed on the leaves on which they live.

My observations indicate that the relationship between these two species is beneficial to both species. The plant provides the food for the larvae and adults while the adult ladybirds help to pollinate the flowers. 

This article was published in The Times on 16.11.11