Category Archives: Photography

15 mosquito-control strategies and devices that don’t work

Leave a reply

Health officials love to remind people to use DEET and other CDC-approved repellents, but they tend to shy away from telling the public what doesn’t work. As a result, millions of people embrace ineffective techniques and gimmicks. These people are not only subjecting themselves to annoying mosquito bites, they are increasing the likelihood that family members will contract West Nile virus disease, Zika virus disease, eastern equine encephalitis, and other mosquito-borne diseases. So I thought I’d make a list of the top myths and scams just in case skeptical people are Googling.

1. Mosquito-repelling plants

Despite the claims of thousands of posts on Facebook and Pinterest, there are no plants that, when planted around your yard, repel mosquitoes. And, just to be clear, the plant marketed as “mosquito plant” does not repel mosquitoes. I know this is deeply upsetting news to many. I’m just the messenger.

2. Ultrasonic devices and apps

None of these have been found to work (details). It’s too bad. It would be really cool if they did. The FTC has taken some companies to court. There is, however, a device called The Mosquito that is effective at repelling teenagers.

3. Bags of water suspended from ceiling

This belief is common in Mexico, Central America, Spain, and certain pockets in the U.S. south. It’s a variation of the equally-ineffective tradition of hanging bags of water to repel house flies.

Bag of water to repel mosquitoes

4. Listerine

Nope — even when mixed with other ingredients like beer and epsom salts, spraying Listerine around your yard won’t repel mosquitoes. Just another internet rumor started by somebody with too much free time.

5. Citronella candles

Citronella candles only seem to work if you surround yourself with a lot of them, ideally in a protected area so that wind doesn’t dissipate the smoke. Similarly, Tiki torches that burn citronella-laced oil are ineffective. They smell great, though. The pleasant smell most likely contributes to the strong placebo effect. People absolutely believe they work even though they do not.

6. Bounce dryer sheets

Per one study fungus gnats (which don’t bite) were mildly repelled by dryer sheets. I’d wager these sheets might actually be attractive to mosquitoes because some species home-in on perfumes.

7. Wrist bands with natural oils

At best, wrist bands will reduce the number of mosquito bites on your wrist simply because they can’t bite through the plastic. But they will not emit enough volatile compounds to shield the rest of you. NB: currently there are no wristbands that contain DEET or other CDC-approved repellent. Details.

8. Stickers laced with natural oils

Stickers only prevent mosquitoes from biting the flesh directly underneath the sticker. You’d need an awful lot of stickers for full protection. If you can rock that look, I say go for it. Note, same conclusion for the stickers that claim to infuse your bloodstream with B1.

9. Garlic

Eating garlic does not deter mosquitoes. It just deters other people.

10. Vitamin B1, B6, or B12 pills or patches

Nope, nope, and nope. Details. More details.

11. Mozi-Q pills

Just another scam. Details.

12. Bug Zappers

These devices are adored by people because they make a satisfying crackle when an insect meets its end. Indeed, people who own these seem to delight in the attention these things get when friends come over in the evening. But if you dump all the carcasses on a table and sort them (good family fun), you’ll find that only a very small fraction of the victims will be mosquitoes. In one study, 0.22% were mosquitoes. Mostly you’ve just electrocuted thousands of small, defenseless moths and night-active beetles. That’s a lot of bad karma. More details.

13. Dynatraps

These don’t appear to work. I’ve tried two and can confirm. If you’re still on the fence read some of the many 1-star reviews on Amazon.

14. Tubes of yeast and sugar

Contraptions filled with yeast and sugar are really good at attracting and killing fruit flies, ants, and wasps. They will not control your mosquitoes. One of these (the Spartan Mosquito Pro Tech) has an EPA registration but don’t be fooled it’s still a complete scam.

15. Bats and birds

Sadly, it’s a myth that constructing a bat or bird hotel in your backyard will eliminate your mosquito problem. Bats and birds will certainly eat mosquitoes under some circumstances (e.g., when they are caged with nothing else) but under natural conditions they prefer to eat larger insects. You should still construct bird and bat houses, though. Details. Again, I’m just the messenger so please don’t be angry at this news.

Trypoxylon collinum defending nest from cuckoo wasp

Leave a reply

Below is a series of photographs of a cuckoo wasp (likely Caenochrysis sp.) attempting to gain entrance to a nest of Trypoxylon collinum (Crabonidae) to oviposit. Normally the cuckoo wasp will just wait until the nest is empty, but on this occasion she took more active measures. The nest is inside a section of Monarda fistulosa (wild bergamot) and is packed full of paralyzed spiders.

The first photographs shows the cuckoo wasp slowly approaching while the guarding male gnashes his mandibles and looks threatening. This goes on for several minutes. The cuckoo wasp just gets closer and closer.

Finally the cuckoo wasp is close enough that the male lunges out. It was so fast he’s just a blur. The cuckoo wasp doesn’t back up.

The male continues to parry with the cuckoo wasp, which also is equipped with formidable mandibles. At no point during this interaction do I see the cuckoo wasp back up. She’s completely calm.

Here’s where I was surprised. Out of nowhere the female Trypoxylon wasp comes back and the male immediately leaves the nest to escort her back inside the stem (as he always does). In that instant the cuckoo wasp darts inside to oviposit. I didn’t catch any of this drama but the photograph below shows the male outside the nest and the female inside (you can see her head). They must surely know there’s a parasitic wasp inside, laying eggs, right?

Now comes the part where the female disappears into the nest for a few seconds. I can hear loud buzzing. Then the female leaves and the male goes back inside. The cuckoo wasp is still inside.

The final photograph is the male glaring at me. The cuckoo was is still inside the nest because I can hear her buzzing. After about 20 minutes I can still hear her. Then it becomes quiet. The tube was walled up the following day so I’m guessing the trypoxylons entombed the cuckoo wasp. I can’t confirm this, however, because the two days later when I checked the tube it was uncapped. Perhaps the cuckoo wasp recovered from being paralyzed or damaged and chewed her way out, or maybe a bird came and pecked away the cap — there’s no way to know.

In researching this phenomenon I found one paper with good detail about how cuckoo wasps gain entry to the nest. According to Muschini and Donatti (2012), a Chrysididae will approach a nest of Trypoxylon agamemnom from the top and then attempt to slide in between the male’s antennae. I would love to see a video of that.