Toxomerus and wild areas

I’ve noticed something about Toxomerus spp (Hover Flies). Along the Red, there are ‘rewilding’ places. Grass is not mown and trees/shrubs are allowed to grow naturally. I see lots of them in these areas. Move 10 m away to the mown part, none. Even on dandelions. Only ants on those flowers.
Would this be from a lack of habitat for larvae? They eat smaller insects.

Lawns are ecological deserts for a lot of reasons, possibly including use of chemicals being sprayed. I’m seeing plenty of Toxomerus nectaring on flowers in gardens close to mowed areas, but have yet to find larvae. I haven’t particularly searched for them either so maybe I should pay more attention to that. I think the species I have in my yard feed primarily on aphids as larvae, so they would depend on having plants with aphids available. Plenty of those around my yard, not sure if there would be any aphids on grass though.

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In a travel I did to the southern parts of Pantanal in Brazil one month ago I came across vast plantations of maize. While driving in the middle of this corn-sea we had to stop several times to clean the windshield because the amount of Maize Hover Flies (Toxomerus politus) that got runned over was so great that we used several loads of water from the windshield cleaner to be able to see anything.

Also whenever we opened the windows or stopped somewhere, we would receive a visit of several of those flies that landed on us to probably lick our sweat or something. Some local people or tourists were even afraid of them thinking they were bees or wasps.

As soon as the maize plantations got scarce and were replaced by the local Cerrado, there was no more hover flies to be seen. So yeah, they are very connected to this plant, specially during this stage of the maize where it was flowering. This species looks common in eastern US too, so I guess people there might encounter them in this manner too.

I’ve seen other Toxomerus species in my garden and in more wild areas before, but never in such numbers. I wonder if the farmers know not to use chemicals during this stage since these flies do no harm and even help with the crops when their larva feed on aphids and such. Not to mention they fall prey to a number of other creatures too. Either way it felt like there was a lack of predators for these flies there.


I have seen them on mowed places with dandelions. But once the vegetation grows they hang around the less mown spots. My city does not spray pesticides unless there is a mosquito problem. I don’t think it much difference, but they don’t use it for weed control.
@fmiudo That’s what I’ve noticed, although not to that extent!

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I see them in mowed lawns but I agree, they seem to prefer less mown spots or edges.

With regards to T. politus, their larva actually eat the corn pollen rather than aphids like most other Toxomerus do. They’re uncommon here in southern Ontario, but I see observations showing hundreds of them from the Midwest in the US where there’s even more corn. I think they can eat pollen from some other grass species; I’m curious if they were always around but uncommon or if they spread into the US and Canada with corn cultivation.


i really wish we could get away from this term. Deserts are super biodiverse and ironically in this context, have tons of insect diversity. An ecological desert would have high native diversity. Using desert in a negative context harms efforts to conserve deserts which are threatened as much as any other habitat, sometimes more. I am not picking on you in particular as this language is widespread. Just hoping i can influence you to tweak your language a bit to help us conserve deserts :)


We do use odd language sometimes. Where I live, a mowed place is distinctly void of biodiversity, compared to a more ‘natural’ place. To me, who has never been in a true desert, I can see using the term, as a metaphor for a barren place. Mind you, people say that about the Great Plains too.
I dislike a lot of the terms humans use for what is beyond our ken. Nature connotes something mythical, magical. Wildlife connotes something untamed. When referring to life other than human, I prefer to us ‘non-human life’. It encompasses all the life forms that humans, in general, find incomprehensible. Trees, plants, bacteria, fungi, invertebrate life. Humans tent to ignore the fact that if these organisms live where we live, they are merely exploiting an environment. We don’t like these ‘invaders’, so seek to eradicate them. Some, like bedbugs and fleas, should be removed, but our homes are also part of the non-human world’s environment.

right, i mean people do the same about wetlands and rain forests. but that has decreased because people are starting to see the value in those ecosystems which is really good. But fewer people see that deserts have value too. They arent devoid, they look different from a forest yes, but they are just as full of life.

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Point well taken - I profess my ignorance of desert ecosystems, never having had a chance to visit one yet. I was just picking up a commonly used phrase. Lawns are a man-made landscape feature, often featuring a monoculture or just a few species of non-native grasses. What other term would you suggest to use?


i use ‘wasteland’ but ‘void of diversity’ as used by mamestra works too.

And i hope you get to go to a (good ecological condition) desert… they are so neat… :)

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For some of us, that is a good connotation.

Of course, for those of us who grew up with Peterson Field Guides, “waste places” are a biodiverse habitat as well – usually predominantly “weedy” species, but that is a human judgement, as the plants of “waste places” are often edible or medicinal, and indeed, may have been introduced for that very reason.

Interestingly, depending on which translation of the Bible you use, “desert” and “wilderness” are both used to translate the same word from the original language, and in Portuguese, the word for wilderness is deserto. Both words originally meant a “deserted” place, that is, one where people did not live.

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in a sense one could use ‘suburb’ or ‘lawn’ as a word to describe this complete absence of life, but that’s kind of circular here.

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Seeing that term isolated like that makes me realise it didn’t say what I wanted it to say. I wanted to imply that the word indicates areas which are outside human control, and only need human intervention to make them tamed. Language!
I agree with you about the untamed part. It’s a good connotation for me, too!

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