Bug of the Month: July – Mosquito
Much to my chagrin, there are no July flies or July beetles. There are only mosquitos. I’m sure the vast majority of my readers are familiar with these little terrors, so I will avoid waxing too eloquently on their maleficence. Instead, I will first speak to the etymology of their entomology. “Mosquito”, a suspiciously Spanish sounding word, is none other than the diminutive of “mosca” or fly, which belies the common idea that mosquitos are sent directly from Hell a few days after rainstorms. Mosquitos belong to the cosmopolitan order Diptera, the true flies. From the lowly housefly to the extremely derived bat flies that have evolved into blood-sucking bat-parasites (do not fret, I will be dedicating a full BOTM to those beauties), Diptera is wildly diverse both in form and function; however, all true flies have only one pair of wings when wings are present in the adults. The second, hind pair of wings is replaced with weird, gyroscopic, wind-sensing stabilizers called halteres, hence “di-ptera” or two-winged.
The Diptera are one of the holometabolous insect lineages, meaning they go through a complete metamorphosis. Mosquitos, in the family Culicidae, lay eggs like most flies. Where they lay their eggs depends greatly on the species with some favoring holes in trees, others favoring salty puddles, and still more only laying eggs above the water line in containers so future rains will submerge them. These eggs hatch into larvae, or wrigglers due to their characteristic movements, which are analogous to maggots if you would like to be more grossed out, or caterpillars if you have had enough pearl-clutching for one day thank-you-very-much. Mosquito larvae live off of microbes and algae that accumulate near the surface of water, diving down to safer depths when disturbed. Once they have had their fill and completed several larval molts, wrigglers become pupae. A mosquito pupa looks somewhat similar to a tiny shrimp with a giant head, which is actually the thorax, or central body segment, as the pupa develops flight muscles. About five to fifteen days after hatching, summertime mosquitos are generally ready to emerge as adults thanks to abundant heat and resources. At adulthood, life styles diverge greatly between the sexes. Oddly enough, only female mosquitos feel the need to be blood-sucking ectoparasites with piercing proboscises. Adult males spend their time either generally minding their own business, seeking out their bloodthirsty counterparts for the sake of posterity, or pollinating flowers to procure pleasant nectars. That is right, mosquitos are actually good for something! So next time someone tells you mosquitos would not be missed if they disappeared off the face of the planet, you can come back with the assurance that we might have very slightly fewer flowers.
Of course, if mosquitos disappeared off the planet there would be much more profound changes than slightly fewer flowers. Namely, human death from disease would diminish dramatically. Mosquitos make up the most dangerous group of animals on the planet. Their females vector viruses, foster filaria, propagate protozoans, and broadcast bot fly larvae (yet another Dipteran that requires full BOTM service). Some notable mosquito borne illnesses include malaria, yellow fever, dengue fever, Chikungunya, and Zika. Malaria alone killed 731,000 people in the world out of 216 million cases in 2016. While 90% of those cases were in Africa, malaria stretches across the globe primarily affecting those living below the poverty line in the tropics. Researchers have begun to fight the Anopheles mosquito, the vector for malaria, by releasing millions more of them. This may sound counterintuitive, but the released mosquitos are all sterilized males. Since males do not feed from humans they cannot spread malaria, and sterile males will compete with fecund males to mate with females thus reducing the next generation’s population significantly. Sterile Insect Techniques, or SIT, have been very successful in the past. The screw-worm fly, a parasite of cattle, other livestock, and occasionally people, is an example of a pest Dipteran that has been successfully eradicated from the conterminous United States and Mexico through SIT. Without SIT, we would have a lot more myiasis, or maggots infesting living flesh. We would also have a lot more subsequent BOTM columns about said myiasis since I find myself oddly motivated to gross out as many people as possible. Let me be honest, you’ll never be done clutching your pearls here at Bug of the Month!