The Desert Responds: Tadpoles and Hackberries

Last Saturday marked our first significant monsoon rainfall, measuring in at 1″, and neighboring parks allow us to observe how the desert has responded.

Four Days Later – Tadpoles in Temporary Ponds (Rain Pools)

Although the above species has yet to be determined, tadpoles can hatch from eggs in as little as 15 hours, and develop into toads in a week.

[Couch’s Spadefoot toads] Their eggs have been known to hatch in just 15 hours, and they can complete the transformation from “tadpole to hopper” in as little as a week — assuming the puddle they are deposited in lasts that long.

In addition to the all-important moisture, amphibians are drawn out this time of year by another monsoon mainstay: flying ants. After a storm, Rosen said, swarms of the insects will emerge, touching off a feeding frenzy by frogs and toads.

Tucson.com

A number of toads and frogs call the Sonoran Desert home, including:

Spiny Hackberry Flowers Are Hard to Find, but Just Listen for the Buzz
Spiny Hackberry (Celtis pallida) with Fruit

Inconspicuous yellow-green flowers April-October depending on rainfall. Berries ripen July-December.

The edible berries are sweet to man and birds. Hermit Thrush, Northern Cardinal, towhees, Phainopepla, Townsend’s Solitaire, Cedar Waxwing, thrashers, White-crowned Sparrow and House Finch are among the birds likely to be seen at Desert Hackberry when in fruit.

Two fascinating butterflies use this plant as a larval host. The Leilia Hackberry Butterfly (Asterocampa leilia), burnt orange with black marginal spots, will almost always be found patrolling nearby up and down a wash just a few feet above the ground stopping frequently to perch on the ground.

…Another butterfly that feeds on hackberry as a caterpillar is the Snout Butterfly (Libytheana bachmanii), also colored burnt orange. The adult butterflies have a long snout formed from elongated palps (mouthparts), and unlike the hackberry butterflies, are avid nectar feeders especially at Seep Baccharis.

Arizonensis

Worst Months for Plants in Phoenix

Although you may initially assume that the months with the hottest average temperature pose the biggest threat to plants, other factors also contribute to plant stress levels.

Let’s look at a table of average weather in Phoenix:

Temps of 100 plus are common June through September.

July and August pose additional challenges for plants, with average nighttime lows in the 80s. Plants that use CAM respiration can struggle and growth may stop, leading to root rot.

Monsoon officially starts in June, but Phoenix typically starts to benefit around mid-July.

So what factors affect plant stress during the hottest months?

  • Daytime high temperature
  • Nighttime low temperature
  • Humidity
  • Rainfall

June

Daytime temperatures break the century mark and may even soar into the 100+ degree zone. Low humidity, lots of sun and little rain make this an extremely challenging month, especially for non-desert adapted species. Cell damage can occur at about 115 degrees for broader leafed plants under these conditions. Applying extra water during June may not cure the stress because plants are not able to function at a level where they can overcome evapotranspiration.

In addition to low rainfall, deserts are characterized by a high rate of water loss from the ground (evaporation) and through plants (transpiration). Together this is called evapotranspiration. Potential evapotranspiration is the amount of water that would be lost through evaporation and transpiration if it were available.

What Is a Desert – DesertUSA

Protecting non-desert adapted plants with a 40% or 50% shade cloth will help, especially during the first year. Another helpful practice is to plant in fall instead of spring so there is more time for plants to get established.

July

The first couple of weeks can be similar to June, depending on when the Monsoon engine gets up and running. Rising humidity levels provide a break from the sun’s rays and allow plants to get a foothold against evapotranspiration.

Clear dry air transmits about 90% of available sunlight to the ground on a typical desert day compared to 40% in a typical humid climate.

What Is a Desert – DesertUSA

Cloudy days and rainfall also provide relief for stressed plants, resulting in new growth and flowering. Nighttime temperatures may be high enough to cause issues for CAM plants, resulting in root rot – this mostly affects non-Sonoran desert plants.

CAM is an adaptation for increased efficiency in the use of water, and so is typically found in plants growing in arid conditions. (CAM is found in over 99% of the known 1700 species of Cactaceae and in nearly all of the cactii producing edible fruits.)

Wikipedia

August

Monsoon continues through August. Average rainfall and nighttime lows are similar to July and average hours of sunshine fall by about 7%.

September

Monsoon officially ends September 30th, so humidity, clouds and rain may benefit plants throughout the month. If the days turn arid, though, high daytime temperatures can pose issues similar to June. Average daily temperatures are down a few degrees from June/July, hours of sunshine are down about 10% and rainfall averages begin to decline.

Best Months to Observe Butterflies in Phoenix

Butterflies are most active when it’s warm and when nectar sources are readily available. So what are the best months to observe butterflies in the Phoenix Sonoran Desert?

In Phoenix, Queens, Fiery Skippers and Gulf Fritillaries are usually around all summer. You can expect to see a showing of butterflies in the late winter into Spring, but the biggest show often comes in the months of August, September and October.

Western Pygmy Blue, Oct 25, 2021

The three popular months coincide with Phoenix Monsoon and quite a number of blooming nectar plants. Following are some observations from the 2021/2022 calendar years in Phoenix. Note that 2021 was an amazing banner year for butterflies!

Some October Observations

Large Orange Sulphur
Monarch
Painted Lady
Mexican Yellow
American Snout
Dainty Sulphur
Ceraunus Blue
Orange Sulphur
Western Pygmy Blue
Fiery Skipper
Cloudless Sulphur
Great Purple Hairstreak
Queen
Sleepy Orange
Funereal Duskywing
Echo Azure
Arizona Powdered Skipper
Cloudless Sulphur
Tiny Checkerspot (Pinal County)
California Patch
Empress Leilia
Violet-clouded Skipper
Fatal Metalmark
West Coast Lady
Queen
Eufala Skipper
Northern White Skipper

Some November Observations

Western Pygmy Blue
Reakirt’s Blue
Sleepy Orange
Mexican Yellow
American Lady
Checkered White
Orange Sulphur
Dainty Sulphur
Pipevine Swallowtail
Painted Lady
Common and White Checkered Skippers
Variegated Fritillary
Gray Hairstreak
Queen
American Lady
American Snout
Fiery Skipper
Gulf Fritillary
Gray Buckeye
Monarch
Red Admiral

Some December Observations

Painted Lady
Funereal Duskywing
Gulf Fritillary
Monarch
West Coast Lady
Queen
Gray Buckeye
Mexican Yellow
Dainty Sulphur
Ceraunus Blue

Some January Observations

Gulf Fritillary
Queen
Monarch
Reakirt’s Blue
Queen
American Snout
Painted Lady
West Coast Lady

Some February Observations

Mourning Cloak
American Snout
Gray Hairstreak
Sleepy Orange
Orange Sulphur

Some March Observations

Red Admiral
Western Giant Swallowtail
Funereal Duskywing
West Coast Lady
Great Purple Hairstreak

Some April Observations

Marine Blue
Gray Buckeye
Dainty Sulphur
Echo Azure
Sleepy Orange
Common Checkered Skipper
Juniper Hairstreak
American Snout
Painted Lady

Some May Observations

Cabbage White
Northern White Skipper
Echo Azure
Pipevine Swallowtail
California Patch

Some June Observations

Reakirt’s Blue
Marine Blue
Empress Leilia
Ceraunus Blue

Some July Observations

Fiery Skipper
Queen
Queen Caterpillar
Sleepy Orange
Gulf Fritillary

Bee Flies as Pollinators

Family Bombyliidae (Bee Flies): A pollinator with a bad reputation. They are among the many flies that imitate bees, bumble bees specifically. By hovering, instead of landing, they avoid many predators hiding in the flowers.

Adults generally feed on nectar and pollen, some being important pollinators. Larvae generally are parasitoids of other insects, including bees. The adult females usually deposit eggs in the vicinity of possible hosts, quite often in the burrows of beetles or wasps/solitary bees.

Bee flies also facilitate pollination of many species of flowering plants. While they do not land on the flower, they do carry some pollen from plant to plant. It is thought they are just as efficient pollinators of some types of flowers as are the bees and they are more frequent visitors so, in the end, they may a pollinate more flowers than bees.

Banded Bee Fly
Genus Geron
Genus Aphoebantus
Genus Lepidanthrax
Genus Paravilla
Poecilanthrax arethusa
Genus Villa
Genus Anastoechus
Bomber Fly
Genus Lordotus

Additional Resources:

How Many Butterfly Species Live in the Sonoran Desert?

The Sonoran Desert is bounded to the north by the Mogollon Rim, to the west by the southeastern corner of California and down into Baja California, and to the south by Sonora, Mexico.

Desert Museum Regional Natural History: Deserts in AZ, CA and Mexico

There are over 250 species of butterflies in the Sonoran Desert. This rich butterfly diversity is due in part to the varied topography in this desert, which supports a wide variety of microclimates and plant distributions.

A significant number of butterflies are influx species, meaning they enter the Sonoran Desert from other deserts, thorn scrub habitats and mountain ranges. The combination of indigenous and influx species account for the high number of species and make for great butterfly watching.

Butterflies play important roles in the ecosystem. Their larval and adult forms are an important part of the food web and many help pollinate plants. Since they experience comparable environmental pressures and are easy to observe, butterflies are excellent bioindicators of environmental health.

For more information, and butterfly photos:

About Native Bees in the Sonoran Desert – Stings and Nests

Most of the news goes to the Honey Bee, a non-native European import, but there are about 1,000 species of native bees in the Sonoran Desert bioregion. And unlike the general bee stereotype, most native bees are solitary and don’t produce honey.

Whereas honey bees build honeycomb hives and live in large colonies, native bees, with the exception of bumble bees, are solitary and nest in the ground or in cavities like abandoned beetle holes in stems or twigs.

Because most native bees are solitary, it’s up to the female bee to build and provision the nest, and if the female dies, that generation is lost. As a result, native bees do not have the luxury of putting themselves at risk, and don’t sting unless absolutely necessary.

Western Honey Bee (Apis mellifera) is the most common of the 7-12 species of honey bee worldwide. It was one of the first domesticated insects.

About Stings

Male bees don’t sting. Surprised? I was!

Stingers are actually modified ovipositors, which, once upon a time, were used by female bees to lay eggs, so only female bees can sting. (Male bees also don’t collect pollen, and this is one means of differentiating a male vs a female observation.)

Honey bees (female) are the only bees that die after stinging. Native female bees don’t leave their stinger behind, so they’re free to defend themselves multiple times if required.

Nesting Habits and Lending a Helping Hand in Your Garden

A bee nest contains anywhere from one to several dozen nest cells.

For bees that nest in the ground, a female bee digs the hole, typically in a sunny south or east patch of exposed earth. Providing patches in your garden that are away from traffic areas can provide nesting opportunities.

Native bees that don’t nest in the ground take advantage of pre-existing nest cavities, including hollowed out twigs, abandoned beetle burrows, tiny holes in bricks and even abandoned snail shells. There are many ways you can help make your garden a home, for example, by leaving snags (dead trees), not removing leaf litter until late spring, or providing nest cavities made of dead wood, dead stems or brush piles.

If you’re creating or modifying a pollinator garden in the low desert areas of Maricopa County and adjacent areas and want to help support native bees, a great set of guidelines and resources are provided by the Maricopa Pollinator Pathway project. Consider joining the project by adding your garden, it’s free! The Maricopa Pollinator Pathway Comprehensive Habitat FAQ is a great way to learn more about what makes a great pollinator habitat.

The Xerces Society also has great information about how to support ground nesting bees, cavity nesting bees and bumble bees.

Another great resource is The Bees in Your Backyard, by Joseph S. Wilson & Olivia Messinger Carril.

It’s June – where are all the native bees?

A hike in a Phoenix nature preserve today revealed very little in bloom, and consequently few native bees or butterflies.

Most of the Sonoran Desert native bees have just one generation per year, so, unlike the non-native Western Honeybee, many native bees will only be active and visible during the Spring or Summer wildflower blooms.

During my hike today, the only flowers I observed were on White Ratany, which was being visited by a bee species whose flower visits were so brief it would take an AI to get a photo,

White Ratany

California Barrel Cactus, whose flowers weren’t yet opened,

California Barrel Cactus

and Coues’ Senna, which had mainly gone to seed but still managed to produce flowers.

Coues’ Senna

Native bees feed on pollen and nectar as well as flower oils for germicidal and bonding properties. Many are solitary, meaning they don’t belong to social hives, and make their nests and brood by burrowing into the ground or using tunnels in wood made by wood-boring beetles.

In my yard in North Phoenix, the native bees seem to have disappeared for a week or so before I wrote this post, so I figured they were gone for the season, even though there are plenty of Desert Marigolds, Zinnias, Sunflowers, Rush Milkweeds, Lantana and Desert Willows in bloom.

But then they reappeared. If native bees for the most part have only one generation per season, how can they be gone and then come back?

So I reached out to Elliott, our resident native bee contributor, and he had a bit of light to shed on the situation:

There’s a few things. Bet hedging, where not every egg hatches every year in case of droughts. Seasonality of host plants for sure and what else in the area is providing food that might be attracting them away from your yard. Pesticides and lack of suitable nesting habitat is a big urban problem. Also, there’s usually small bees going undetected by human observers due to their size and speed.

Elliott Gordon

In addition, I reached out to my friends in the Pollinator Gardening in the Southwest facebook group and asked what they are seeing in their yards.

The larger longhorn bees are active this month on Gaillardia pulchella flowers; Svastra obliqua and many Melissodes males and a few females of both species. The female Valley Carpenter Bees are still out every day. Lots of Triepeolus Cuckoo bees and Anthophora californica bees. The Svastra duplocincta time their June emerging with the neighbor’s Barrel Cactus flowering, which it has already and the males and females are now out and about in large numbers. Lots of activity in my Arizona garden even with the 111 degrees we had today. The number of Megachile bees are lower than usual this year, however. Wondering if the various cuckoo bees that showed up this year in greater numbers than previous were responsible.

Kim Neubauer, Phoenix West Side

I see gulf fritillary butterflies daily and occasionally giant swallowtails and queens. Lots of native bees, mainly sweat bees, leaf cutters, carpenter bees, and another that I haven’t identified.

MM, Central/Midtown Phoenix

A few Queens at the Mistflowers, weekly visit of Giant Swallowtails to the orange tree, a few Skippers at zinnias and Mexican Evening Primrose. Plus 3-4 species of native bees on the sunflowers, desert lavender, globe mallows, coreopsis, fairy duster & Superstition mallow.

MH, NE Phoenix

Phoenix temps 110. Not seeing too many 🦋 besides gulf fritillaries. Bees and wasp come around splashes in the pool to try and get water.

VC, Phoenix

A lot. At my fountain plants.

SBC, Phoenix

Plenty! My garden is full of yellow flowers and pollinators, but the wild spaces are brown and dry from lack of rain. I saw yard bee species 82 last weekend and yard moth/butterfly 100 last night.

Elliott Gordon, Albuquerque

You can learn more about native bees at:

Musings from a Phoenix Pollinator Garden

10june22 Yellow-legged Mud-dauber Wasp, Bee Fly (genus Geron), Queen butterfly, White-winged Dove, Bee Fly, Fiery Skipper, Smoketree Sharpshooter.

It’s been a hot week, with temps of 110 degrees F and above. Can’t remember the last time it rained, but forecasts are favoring an average to above average monsoon season this year, yay!

In the mean time plants are requiring extra water to carry them through this oven dry period. Water is becoming a scarce resource here in the southwest US, so I’m glad that all plants are being watered by drip irrigation, and swales are in place to retain rainwater in the garden, when, in fact, it rains again.

Down the road I see water conservation becoming more front and center, possibly leading to policy enforcing reduced water usage. The landscape is about 2 years old now, with some new plants added this year, so the watering schedule is geared towards less frequent, deep waterings to promote deeper roots that will hopefully make the garden more resilient to reduced waterings down the road, if necessary.

Anyway, on to some photos of interesting insects in the garden, and the plants they like to visit.

Yellow-legged Mud-dauber Wasp on Cascalote, feeding on Psyllid honeydew
Bee Fly, Genus Geron, on Lantana
Queen butterflies on Gregg’s Mistflower
White-winged Dove
Bee Fly on Zinnia
Fiery Skipper on Lantana
Smoketree (Glassy-winged) Sharpshooter on Sunflower

Found a most unusual insect on a sunflower today: Homalodisca liturata (Glassy-winged Sharpshooter). Considered a pest, and a major vector of the bacterial Pierce’s disease of grapes, phonypeach disease, plum leaf scald, and oleander leaf scorch in southern United States and northern Mexico.

The glassy-winged sharpshooter is an extremely polyphagous insect, feeding on the xylem fluid of over 100 known species of plant, in at least 37 different families. The actual feeding on plants causes little damage.

Musings from a Phoenix Pollinator Garden

7June22 Plants in the garden, and sharing plants from the neighbor’s garden

Most urban and suburban lots are small relative to the natural tracts of native habitat, so there are limits to what we can plant, both in size and variety.

And, it turns out, putting your yard into context with the nearest forage/host area is quite important because many insects are limited in how far they can travel for food and lodging. To some, a football field of length can push limits of mobility.

So if you are close enough to a natural area that you can leverage it’s resources, fantastic! Add one or two specimens of various native plants can still get you to critical mass if considered as shared resources with the natural area. Same goes for sharing other resources, like water and nesting habitat.

Similarly, you can view the plants and other resources in your neighbor’s yards as something to be shared by the pollinator web of animals.

The neighbor behind us has a large Sissoo tree (not a tree that I would recommend), and the birds love the height and cover it affords. Good thing, because our backyard is only 2 years old, and even our fast growing mesquite and palo verdes need a bit more time to become truly comfortable perches.

Other neighbors have citrus, hibiscus and Arizona Yellow Bells to share. Let’s look at how some of the plants in and around the garden are looking on this 109 degree day.

Desert Willow in our garden is loving the heat
Rush Milkweed in our yard is a great nectar source this time of year
Peacock Flower in our garden has come back from a cut-back in the spring
Hopbush is a great low water screening plant in our garden
The Brittlebush finished their late-winter and spring flowerings, providing much needed food
Firecracker Penstemon is still showing a will to flower, but has mostly gone to seed
Desert Marigold is in its second bloom period. Finches love the seeds
Peaking over the fence, a beautiful hibiscus (thanks neighbor)
Another shared resource, loved by hummingbirds, host to Painted Lady and Gray Hairstreak
Arizona Yellow Bells, another great nectar plant (thanks neighbor!)
And Sunflowers have turned out to be a great addition to the vegetable garden

I’ve found some interesting bees on the sunflowers, but no butterflies so far. On the non-pollinator side of things though, the sunflowers attract a wide array of insects from lace bugs, psyllids, long legged flies, assassin bugs and lady beetles! Oh, and birds eating the insects off of the leaves.