Aaron Weinstein, Naturalist 

As any trip to the hiking and outdoors section of a department store will show you, many of us stuck in quarantine are choosing to find recreation and solace outside. Personally, many of my family members who were less experienced in the outdoors found joy exploring green spaces and connecting with nature. While the spring months kept us at a cool 60 degrees, by June, mosquitoes were on full attack mode and sent many of us running back inside. 

With bug spray working for only so long, my friends and family experimented with a variety of defenses, such as citronella plants, oscillating fans and bug zappers, to keep the bugs at bay. As it turns out, citronella plants are only effective if their leaves are rubbed against your skin (even worse than bug spray). The oscillating fan worked well, but only for the part of you in front of moving air; the rest of your body was still vulnerable. Some friends even looked into a bug zapper for their backyard but abandoned the idea after learning how ineffective they are. A 10-week University of Delaware study found that out of 13,000 insects “zapped,” only 30 were mosquitoes

It became a common sentiment to hear someone say the mosquitoes were worse this year. But was this really true? As it turns out, a combination of factors is at play here, so let’s break it down. In 2018, newspaper headlines lamented about the mosquito population tripling, but further research shows this was from heavy rains and flooding that allowed mosquitoes to breed earlier, not necessarily in greater numbers. This past year, we had a very wet spring and early summer, which could explain the high numbers of mosquitoes, especially early on. 

Another factor that can’t be ignored is that Washington, D.C., used to be a wetland teeming with insects. While the waters have been dredged and canalled, the environmental conditions of our area still allow mosquitoes to thrive here centuries later. The humidity alone on a hot summer day will remind you of its past. There is no surprise that the greater D.C. area has a higher number of mosquitoes (and other insects) than many other states, which certainly gives the impression of an increasing population. 

Heavy rains in an area already predisposed to high mosquito populations certainly explains the last few months, but have mosquitos really gotten worse? A quick search will reveal that insect populations as a whole have been dropping significantly over the last decade; an estimated 40% of all insect species may be extinct within this time frame. However, it is not clear that mosquitoes fall into this category, and it’s possible our efforts to combat them may be having unintended consequences on other species.  

At this point, it is hard to say that mosquito populations are increasing. While recent environmental trends have benefitted mosquitos, allowing them to come out earlier in the summer, there’s no evidence that they have actually increased in numbers. Humans outside, however, have dramatically increased over the spring and summer, and the higher exposure could explain why it feels like this year is especially bad. In fact, a supposed 20% of people are more likely to get bitten by mosquitoes due to factors like their blood type, diet, consumption of alcohol or even being pregnant

As we’ve learned, the presence of multiple factors, including our geography and climate, have predisposed our area to be a hotspot for mosquitoes. While we haven’t found data that shows the problem getting worse, the quarantine, poor insect repellent, and the fact that some of us are more attractive to mosquitoes can certainly give the impression of more mosquitoes than before.  

While some days are certainly unbearable, mosquitoes are worth dealing with, at least some of the time, in order to experience Maryland’s natural beauty in the warmer months.