A baraita is brought on our daf that teaches how regarding certain misfortunes (aside from drought), such as itching, locusts, flies, hornets, mosquitoes or a plague of serpents and scorpions, no “alarm” was raised, but a “cry” was raised. The “alarm” is understood by Rashi as blowing the shofar, which was part of the fasting ritual; the “cry” is the recitation of additional prayers.
What were these calamities enumerated in the baraita?
A plague of the insects that are mentioned stems from specific weather conditions that encourage the growth and development of these pests. Zevuvim – flies – were considered so problematic that some ancient tribes had specific rituals and idols whose purpose was to protect them from flies. Yitushim – mosquitoes – are disturbing not only because they are pests, but also because they are carriers of Malaria. The tzir’ah – a hornet (Vespa orientalis) – is mentioned in the Tanakh as one of the instigators of the emigration of the Canaanite nations from the land of Israel (see Shemot 23:28 and Yehoshua 24:12). There is historical evidence that entire cities were abandoned by their populations because of swarms of flies or hornets.
Plagues of serpents and scorpions are also often weather-related. If conditions are right and there is an ample food supply, the sheer number of sustained, live births rises. Under such circumstances we find that these creatures are forced into closer proximity to the places where humans live, and there is more opportunity for interactions with them than we would have under normal circumstances, thus increasing the likelihood of attacks on humans. On occasion the simple fact that there is overcrowding in their natural habitat will lead these creatures to become more attack-prone, as well.