## 1 Introduction  
The horn fly, _Haematobia irritans irritans_ (L.) (Diptera: Muscidae), is an obligate hematophagous ectoparasite of cattle, considered one of the most economically important fly pests of livestock production worldwide [1, 2, 3]. It is a little brown-gray fly between 3 and 5 mm in length, which makes it the smallest biting fly parasitizing beef cattle [1, 4, 5, 6, 7]. _H. irritans_ is widely distributed in many of the temperate, tropical, and subtropical regions of the Northern Hemisphere, including Europe, Asia Minor, and North Africa [1]. In the Americas, _H. irritans_ ranges from southern Canada to temperate areas of Argentina, Uruguay [1, 8, 9, 10, 11], and Chile [11]. In Chile, the species was definitively established in 1993 [11, 12] and nowadays is found between the regions of Arica y Parinacota and Aysen [12]. The horn fly is holometabolic through four successive stages: egg, larva, pupa, and adult fly [1, 5]. The flies spend most of their adult life on the cattle host, feeding and mating only on the host [13, 14]. One day after copulation, females leave the host for egg-laying, just when the host defecates [15]. Then, the eggs are almost exclusively laid on fresh dung [16]. It has been reported that dung ceases to be attractive to flies a few minutes of being dropped [14, 15]. During its lifetime, a single female can produce 78 to 400 eggs deposited in clusters of 20-25 eggs [1, 17]. Hatching occurs 1-2 days after oviposition and the larvae reside within the dung, passing through three instars. The final instar initiates pupariation inside of the dung pat or around the dung pat [1]. Development from egg to adult has been reported at 7-11 [18] and 9-12 days [19], depending on the temperature [20]. After hatching, flies choose an animal host, and they feed off it for the first time. The adult lifetime is between 6 and 8 weeks [21]. It has been estimated that the whole lifecycle of the _H. irritans_ takes 10-20 days when environmental temperature fluctuates between 20 and 30 \({}^{\circ}\)C in places with high levels of humidity [5]. In Chile, flies emerge from November to May, showing a large population from December to March [12]. However, because of climate change, seasonality has decreased, and the season has been extended [13]. Both female and male horn flies use their piercing proboscis [1, 22] to feed on cattle multiple times per day [23, 24]. Fly feeding behavior causes extreme annoyance and stress to cattle, which waste energy in removing flies, principally through head and tail tossing, trembling, and bunching and seeking refuge [25, 26]. It leads to reduced sleeping and grazing time, a worsening of feed conversion efficiency, reduced milk production, and weight gain, especially when the animals are under a massive infestation (>200 horn flies per animal) [23, 25, 27, 28, 29]. Moreover, horn flies are important vectors in the development of mastitis by _Staphylococcus aureus_ and teat atresia [1, 30, 31, 32, 33], and they are also an intermediate host of _Stephanoflaria stiles_, a flarioid nematode that causes skin lesions on cattle [6, 34]. Skin damage includes scarring and fiber separation, which leads to reduced leather quality and lower commercial value [35]. In the US livestock industry, the monetary damages caused by _H. irritans_ were estimated to be USD 876 million annually [36], which, when adjusted for inflation to 2021 dollars, is USD 1.75 billion per year [23; 24]. In Mexico, estimated annual losses amount to USD 231.66 million [37], whereas annual losses in Brazil were estimated to be from USD 150 million to USD 2.56 billion in 2012 [38]. In Chile, the annual economic losses caused by the horn fly were valuated at CLP 25,800 million [39; 40], equivalent to USD 45 million in January 2001 [41]. This estimation did not consider losses produced by reduced reproductive efficiency and leather quality [42]. Nowadays, _H.