Lazy lawnmowers and landscape mullets

By Atticus Murphy

Maybe you’re the type of person who’s interested in nature but don’t know you can help. You live in a city or a suburb, with not much space and just a typical grassy lawn covering what space you have. Maybe you’ve also recently learned that insect pollinators like bees are crucial for our ecosystems but may be experiencing significant declines caused by habitat loss due to humans. What can you do to help, without breaking the bank or spending too much of your time on gardening?

 A lawn with a more and less frequently mowed portion on left and right respectively, showing the diversity of flowers that can emerge when given time to grow (Photo: Sue Pranskus). 

If this sounds like you, there’s a surprisingly simple option available to you: do less! Mowing grass lawns frequently (more than twice a month) is a good way to keep the grass cropped low and cut down on weeds. But this low, flowerless grass lawn is essentially a food desert for bees and other pollinators. Happily, studies have shown that if you simply mow a bit less, your once barren yard can become a buffet for bees in just a few short weeks. Simply shifting towards cutting your lawn every two or three weeks instead of once a week can greatly increase the number of bees and other pollinators that are able to forage there, as quick-blooming “weedy” flowers sprout up from the soil. Instead of treating weeds like unwanted invaders, to help save our native bee populations, treat them like welcomed guests! They’ll beautify your lawn for a few days at a time all throughout the growing season and they’ll do it for free. All it takes it giving them a bit more time between mowing to put up their flowers. 

If you enjoy using your lawn for outdoor activities or are required to maintain it at a certain length by local authorities, reducing your mowing frequency as much as you can within these limits is still a great way to help pollinators by giving flowers more of a chance to bloom before cutting them. Remember, this “lazy lawnmower” strategy for helping pollinators does not require drastic lifestyle changes: instead, it might be totally compatible with whatever uses you get out of your lawn now. Green grass can remain on your property for sitting, lying, and playing, and you can see significant numbers of new flowers all while still keeping your lawn looking well-kempt. If you’re concerned about appearances and don’t want to give over the front lawn to being taller, then consider only letting your back lawn grow out a little. Scientists have nicknamed this practice the “landscape mullet” because like the famous haircut, it’s longer at the back. Because pollinators are able to move around to locate flowers, they will be served just as well by a back lawn with flowers as they would a front lawn.

A monarch butterfly feeding on a mustard flower (family Brassicaceae) sprouting from a grassy lawn (Photo: Rachael Bonoan).

What types of flowers will spontaneously recruit in your lawn? It’s hard to say, and that’s part of the fun! In Massachusetts you might expect to see pollinator-friendly flowers like dandelions (Taraxacum species), clovers (Trifolium species), butter-and-eggs (Linaria vulgaris) and other quick-blooming, low-growing species, like the mustard pictured above. Many of these species may not be native to the U.S., but they are nevertheless great sources of nutrition for native pollinator species. So if you’re interested in helping pollinators but don’t want to make the leap into pollinator-friendly gardening just yet, getting a little lazy with lawn management and welcoming some weeds into your life is a great first step towards making your property a refuge for native insect pollinators. 

Solitary wasps are fierce, fascinating, and totally harmless

In mid to late summer in the northeastern US, several species of large solitary wasp (belonging to the families Sphecidae and Crabronidae) frequent gardens, parks, and other open spaces. Despite their threatening appearance, solitary wasps are totally harmless. They are more interested in hunting other invertebrates–like spiders, flies, and bees–than they are in you. Solitary wasps are carnivores that capture and paralyze insects or spiders to feed their young, with many species specializing on particular types of prey. Unlike hornets, yellowjackets, and other social wasps, solitary wasp females build and provision nests independently of one another. Nesting locations differ among species and may include a variety of cavities both above and below ground.

Great Black Wasp (Sphex pensylvanicus) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

Digger wasps in the genus Sphex nest in the ground. In the northeast, the Great Golden Digger Wasp (Sphex ichnumoneus) and Great Black Wasp (Sphex pensylvanicus) are two particularly common species that can be seen drinking nectar from milkweeds, mountain mints, and other flowers. Females hunt katydids, stinging and paralyzing their prey before dragging it back to the nest. Although they are solitary, digger wasps sometimes aggregate, with many females constructing nests in close proximity. Each nest consists of a main tunnel with a number of side tunnels, each of which ends in a brood cell in which an egg is laid after the cell is provisioned with several katydids. When bringing paralyzed prey back to the nest, female Sphex leave the prey item outside the nest entrance while investigating the nest interior before dragging the prey down. If the prey item is moved slightly, the wasp will retrieve it and inspect the nest yet again. Sphex’s automatic nest-checking routine has captured the attention of several philosophers interested in the contrasting ideas of instinct and free will, inspiring the coining of the word “sphexish” (used to describe actions that appear thought-out and deliberate but are instead actually quite mindless).

Golden Digger Wasp (Sphex ichnumoneus) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

Isodontia grass-carrying wasps are a common sight around houses, gathering dry blades of grass and stuffing them into a crevice to furnish a nest. Grass-carrying wasps are predators of katydids and tree crickets and, like the digger wasps, leave their prey alive, but paralyzed, for their larvae to feed on.

Grass-carrying Wasp (Isodontia sp.) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

The giant cicada killer wasps (Sphecius sp.) are hard not to notice. Reaching lengths of an inch or more, these are among the largest wasps in North America. Even so, these formidable-looking insects are typically harmless. Females are not aggressive and although males may behave aggressively, they are unable to sting. Cicada killers sometimes form nesting aggregations, with many females utilizing the same patch of bare soil while males hover about looking for opportunities to mate. As their common name suggests, cicada killers hunt cicadas, paralyzing them and then flying back to their nest while carrying a prey item heavier than themselves. The wasp larva consumes the cicada and emerges as an adult the following summer.

Cicada Killer (Sphecius speciosus)

Other solitary wasps hunt soft-bodied prey. The thread-waisted wasps in the genus Ammophila are a group of impossibly-skinny caterpillar predators. They can often be seen flying with a caterpillar slung underneath their body, toting their paralyzed prey back to an underground nest. Interestingly, after completing their nests and filling the tunnel with sand, some thread-waisted wasps have been observed using a small stone held between their jaws to tamp down soil at the former nest entrance, a behavior sometimes considered to be an example of tool use!

Thread-waisted Wasp (Ammophila sp.) with caterpillar prey

Though they may lack the charisma of butterflies, bees, and other favorite garden insects, solitary wasps are a diverse group that play an essential part in regulating numbers of herbivorous insects. By leaving patches of bare soil for nesting and planting milkweeds (Asclepias sp.), mountain mints (Pycnanthemum sp.), joe-pye weeds (Eupatorium sp.) , and other favorite nectar plants, you can encourage the presence of these beneficial insects in your yard and enjoy their pest-control services and enthralling behaviors.

Photo Credits: Max McCarthy