Showing posts with label coleoptera. Show all posts
Showing posts with label coleoptera. Show all posts

Sunday, March 9, 2014

The beetle that dwells in churches

Churchyard beetle - Blabs gigas - ħanfusa tal-kantina
The churchyard beetle is one of the larger beetles of the Maltese islands. Some individual specimens can grow up to 37mm long. It prefers to live in dark humid areas and can sometimes be found in basements, cellars, cave entrances and obviously churches.

In Maltese this common species is known as ħanfusa tal-kantina.

The front wings of most beetles are hardened and cover the abdomen and a pair of delicate wings. To fly, most beetles lift their front wings and unfurl the hind wings. The churchyard beetle cannot fly because its front wings are fused together and cannot be lifted.

Inability to fly could leave this species susceptible to many predators but it compensates for its inability to escape from danger by being able to secrete a pungent liquid from glands that are found in the joints of its limbs. Any bird or mammal trying to eat one soon learns to leave this disgusting insect alone.

Unpalatable insects such as the ladybird often have bright warning colours to make them easily recognisable. The churchyard beetle is jet black, probably, because it lives in dark places where colours would not be of any use.

When threatened the churchyard beetle can also change its posture to appear larger. It pushes its head against the ground and extends its hindlegs so as to tilt its body so that its wings face its enemy.

Several closely related species that lives in the Namib Desert on misty nights takes up a similar position to collect water which forms on theirs body. The body then trickles down their back to their head and mouth. 

The churchyard beetle belongs to a family of beetles known as the darkling beetles. A name they got because of their dark colour. The darkling is a large family with more than 20,000 members. In Malta about fifty species can be found a number of which are endemic to the Maltese islands. 

This article was published in The Times of Malta on 5 February 2014.




Sunday, May 20, 2012

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

Wednesday, September 29, 2010

The scarab beetles

Some days ago I found several beetles along the water’s edge at Mellieha Bay. Several more were floating on the water. 

All were dead except for a couple which I collected and moved to a safer place. 

These beetles, like many other insects are attracted to light and they must have been confused by some lights after having emerged from their cocoon and fell in the sea.

The beetles belonged to a very common species of the scarab family. Like many members of this family it does not have a common English name and is known as a scarab beetle.

 In Maltese most beetles are known as ħanfus. Like every identified plant and animal it has a unique scientific name - Phyllognathus excavatus. The males of this species have a structure on their head that resembles the horn of a rhinoceros. There are other scarab beetles with such a horn on their head which are popularly known as rhinoceros beetles.

At this time of the year it is the most common scarab beetle. It is found throughout the Mediterranean to the as to Iran and Crimea and in Senegal.

The scarab beetle family consists of over 30,000 species. Many of these beetles have bright metallic colours ranging in size from 1.5 to 160 mm. The larvae are soft bodied pale yellow or white grubs. 

Most live underground or under leaves away from sunlight. The majority are scavengers and many species live on dung, dead animals or decaying vegetation.

One of the best known species of scarab is the dung beetle which was revered as sacred in ancient Egypt. Dung beetles collect dung which they shape into the shape of a ball and then roll to an underground nest. They lay eggs in it so that on hatching the larvae find a readily available rich source of food. 

This article was published in The Times on 30.09.2010

Saturday, September 4, 2010

The rosemary leaf beetle lives on herbs

Rosemary leaf beetle (Chrysolina americana)
The rosemary leaf beetle is a common beetle that lives on rosemary and other herbs. Its scientific name is Chrysolina americana. Despite its scientific name, it is a native of southern Europe. In the early 1990s it appeared in Britain and during the last decade it has become an established pest on rosemary, lavender and related plants.

It is an attractive beetle with metallic green and purple stripes down its back. . In the sunlight these stripes reflect all the colours of the rainbow - rather like oil on water. This effect is very beautiful to see but difficult to capture on camera.

It is usually found in groups on stems or feeding on the new growth of plants. The larvae are small slug-like grubs which are usually found on the underside of leaves. They are light grey with horizontal dark stripes running the length of their body.

Their favourite food plant, the rosemary is a medium-sized bush of the Mediterranean, recognised by its narrow fleshy leaves, small pale blue flowers and more than anything else by its typical aromatic smell. The bush is usually about one metre high but when hanging down from a vertical rock face it can grow up to two metres. It flowers throughout the year.

The rosemary leaf beetle, known in Maltese as żabbella tal-klin, belongs to the Chrysomelidae family, a group of beetles known as the leaf beetles. This is a family of over 35,000 species, one of the largest and most commonly-encountered of all beetle families. About 60 of these species are found in the Maltese islands. Another common member of this large family is the red leaf beetle, żabbella ħamra in Maltese, which is found in vegetation in the countryside. Adult and larval leaf beetles feed on all sorts of plant tissue. Many are economically important pests of agriculture. 

This article was published in The Times on 05.01.2010

Wednesday, July 21, 2010

Insect diversity


Last Sunday I photographed a soft-winged flower beetle at Wied Qirda. This is a small shiny green beetle known in Maltese as ħadranija tal-ward

It is a common species often seen on yellow flowers such as the Cape sorrel (ħaxixa Ngliża) and the crown daisy (lellux). The beetle I photographed on Sunday was spotted by my three year old son.

 I did not see it myself because it was walking on the stem of a grass about 10 cm from the ground and out of my line of vision. Children have a different perspective of their surroundings and often manage to see things which grownups miss. 

I often encountered adults who say that they remember seeing more flowers and insects when they were young. They remember more than anything the gourd ladybird (nannakola tal-faqqus il-ħmir) an insect that lives on the squirting cucumber (faqqus il-ħmir). Both the squirting cucumber and the ladybird are still common in the Maltese countryside. These people fail to see them because they do not know where and how to look.

This does not mean that insect numbers have not gone down. The amount of countryside has shrunk drastically during the last 50 years and it continues to be gobbled up at an alarming rate in spite of the fact that we are more aware about the need to conserve it. 

Changes in agriculture, especially the use of pesticides have had their toll as well. Pesticides kill insects and many kill indiscriminately. They kill pests as well as other species some of which are beneficial such as bees especially if they are used indiscriminately. 

For several decades farmers have been urged to spray their crops. As the pests became immune to the pesticides stronger pesticides in larger doses had to be used. Now they are being told to stop using them and many are confused. Some have been spraying their crops throughout their whole life and do not know otherwise. 

Although many are now realising that something is wrong they find it hard to accept that what they have been told for the past thirty or forty years was not exactly right and find it hard to change. A small number are now starting to practice more environment friendly agriculture and more should do so for the benefit of everybody including nature.

This article was published in The Times on 03.03.2010