Black fly: what is the best repellent?

The black fly (simulidae) are diptera (bugs with two wings) of about 2 to 5 mm, dark in color and somewhat chepy in appearance. Until four days ago they were studied simply because they belonged to certain aquatic ecosystems, but now they are making headlines because, beyond the river, they have begun to be found en masse in  Zaragoza ,   Murcia  or Madrid  (especially in the municipalities near Jarama and Henares rivers).

Different causes are pointed out for this circumstance to have occurred, mainly the excess of macrophytes and aquatic plants in rivers. And it is that the black fly is an animal of customs and likes to grow up in macrophytes, which are water plants that are observed with the naked eye (although there are many categories, of the water lily type, to understand us). In recent years, the presence of these aquatic plants in rivers has increased. The rains help to clean the river banks, but when the flow is low, these aquatic plants grow strong and proliferate. And with them, the black fly, which finds in this vegetation a beautiful house to move into.

Unlike the tiger mosquito, which flies through stagnant water , the black fly likes clean water. And in this, the black fly of the present is also lucky: on the one hand, new irrigated areas have been created that represent new “urbanizations” of all luxury to enter to live , and on the other, today in general we enjoy some rivers with water of higher quality than a few years ago when spills were made and hostile situations were created for simulids to procreate.


The black fly does not bite, it bites

The black fly is a telmophage, an ugly name to call something even uglier: they feed on hemorrhages. As it is. Once again, they are the bad guys in the movie since it is the females who need the blood to lay eggs.

They have a mouth in the shape of a saw (in the photo you can see how ugly they are) with which they make a wound in the skin in which they inoculate saliva, leaving a central red dot accompanied by inflammation. Do not believe that this saliva is any spit. No. Your saliva is designed to the millimeter containing anesthetic, vasodilatory, anticoagulant and antithrombinic substances (try to say it out loud) that act as a “smoke bomb”. On the one hand, they ensure that the host does not feel pain at the time of the sting, but at the same time they prevent blood clotting and favor increased blood flow in the area.

Nothing is forever, and neither is saliva anesthesia. Generally when night falls, things start to hurt or itch. It can even cause edema. In addition, this saliva is responsible for the allergic reactions that take place in some affected.

 What is the best repellent for the black fly?

As with keeping your cousins, mosquitoes and tiger mosquitoes at bay, the use of DEET (diethyltoluamide) is recommended. In this case, at high concentrations (45% or higher). The biocide citriodiol may also be effective at high concentrations. If someone wants to delve into commercial names, in the post ” the best mosquito repellent ” you have more information to go “on target” to the pharmacy.

In addition to using repellents, it is recommended to avoid walking near the river beds where they live first thing in the morning and afternoon, which are their favorites, and when we do it, it should be with boots, socks, long pants and a shirt. long sleeve. If possible, Adlib Ibizan roll, all very white, to find out if the bicjos are approaching us.

What do I do if a black fly bites me?

We have already agreed that they do not “bite” but “bite”, but the measures are similar to those of other mosquito injuries: using ice first to reduce inflammation. In addition to using emollient creams or ointments to avoid scratching, depending on the symptoms and characteristics, assess the use of anti – inflammatory drugs , antihistamines or corticosteroids . More information on all this in this post .

If allergic reactions are observed (especially in places other than the sting, such as swelling of the lips or difficulty swallowing), you should go to the emergency department. It is important to monitor the evolution of the bite before other symptoms such as fever, muscle pain or vomiting, since an infection (infectious cellulitis) could occur.

Can the black fly transmit diseases?

Fortunately in Spain we should not worry, but it is important to know that numerous species are vectors of the parasite Onchocerca volvulus, which causes onchocerciasis or blindness in rivers. It is mainly distributed in tropical countries, with sub-Saharan Africa being the most affected.

Can anything be done to prevent the black fly infestation?

It is possible and in fact it is worked on, although to be effective it must be worked together on four fronts:

  • Environmental management:Elimination of the substrates that shelter the black fly by cleaning the vegetation in the channels.
  • Chemical control: The use of insecticides is generally discouraged for not having limited efficacy and not being selective. They present potential risks to public health and the environment, although they can be a resource in cases of emergency.
  • Biological control:Due to its specificity, the most recommended system is the biological control of the larvae by means of the spores of the Bacillus thuringiensis serotype israelensis bacteria. It is a bioinsecticide that is “eaten”. Once inside the larva, it causes osmotic imbalances that break the wall of the intestine, causing septicemia and causing death.
  • Cultural action: Or provideinformation and carry out public awareness campaigns


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