HOME

PRODUCTS

TECHNICAL ASSISTANCE

WHO WE ARE

CONTACT US

CURIOSITIES REGARDING FLYING INSECTS.

Insects' Vision

Insects (arthropods) can have three types of visual receptors or a combination of more than one of them.

• Skin Receptors: cells not solely dedicated to vision.  Some species have parts of their bodies which are photosensitive.

• Ocelli: also called "simple eyes" as they are composed of a sole receptive unit or “ommatidia”. The majority of insects have these ocelli whether in isolation or in small groups.

• Compound Eyes: Flying insects which need a greater visual resolution have what are known as "compound eyes" which are formed of multiple ocelli or unitary receptors (ommatidia) (some species of dragonflies were found to have as many as 30,000).  Each ommatidia is made up of: a lens forming the surface side of each one of what is called a "facet", a transparent crystalline cone, photosensitive cells arranged in a radial fashion around the rhabdom which functions as a wave guide transmitting the signal which creates an inverted image onto the photosensitive retinal cells and pigmented cells which separate each receptor from the rest.

So, we see that the images that are formed in the brain of an insect with compound eyes is made up of a mosaic of miniscule individual images that are combined to generate an image formed of small "dots".  In a certain way, it is similar to a digital image in which each pixel is the image captured by one specific ommatidia. 

Even though these compound eyes are superior to ours on some points, we can say that in general, insects do not see as well as we do. In fact, returning to the example of the digital image, we observe that insects see better or worse depending upon the number of ommatidium present in its eye and as a general rule, this number is not high enough to equal the quality of the image that we capture. 

Advantages and disadvantages

According to some studies carried out, we can affirm that a bee sees about 60 times worse that we do.  That is to say that an object that we can discriminate between at 60 metres, a bee can only distinguish at one metre. Part of the problem is also that compound eyes are unable to focus.

But not in everything are they disadvantaged: compound eyes bestow upon the insect an excellent peripheral vision, thanks to the arrangement of the ommatidium, which in those insects with better vision are usually arranged in a semi sphere.  

Insects and Colour 

For most insects, the images which are formed in the brain of those with compound eyes are made up of a mosaic of miniscule individual images that combine to generate an image formed of small "dots".  

They have two types of pigments, which permit them to differentiate some tones of colours. The insects' pigment receptors are much more shifted towards the ultraviolet than humans, which allow them to see this radiation perfectly. One of these pigments absorbs blue and ultraviolet and the others absorb green and yellow. This means to say that they are not able to discriminate pure colours from others that are a combination, more or less like the colour-blind but with the frequencies shifted towards ultraviolet. Moreover, they cannot see pure red very well.

Some insects such as bees, bumblebees or dragonflies have three types of pigment receptors because of which the can differentiate between colours 360 nm (ultraviolet), 440 nm (blue-violet), and 588 nm (yellow-green-red) within their visual spectrum, which means that they can distinguish between any colour or combination within a margin that goes from ultraviolet up to yellow-red (without reaching pure red).  

If we pay attention, it can be seen that the lights that are used to attract insects are always a blue-violet colour as this is the colour that they see well. This can be tested with a red light and it would be seen that insects are not attracted to it.

Source: Plagasbajocontrol.com

If you wish to know about our other articles about fly, mosquito and wasp killers and addities about these flying insects,

please click below.