In the low desert, tree pruning can be done almost year round, but here are the suggested best times to trim:
Deciduous trees – winter dormancy (December through February)
Citrus – after February to avoid frost damage
Conifers – winter dormancy
Natives – summer
Mesquites: Spring or early summer to prevent damage from monsoon storms
Palo Verdes: Avoid summer pruning since they are sun sensitive
Don’t forget to sanitize your pruning equipment before use, and in between pruning different trees to prevent virus, vascular fungus and bacteria infections. Don’t prune at oozing cankers. You can use:
Senegalia greggii (formerly Acacia greggii) is native to the southwestern united states and northern Mexico at elevations below 4500′. It’s a large thorny shrub or small tree growing to 20′ tall. Flowers are fragrant. Full to part sun, low water and hardy to 0 degrees F.
Flowering Season: J F M A M J J A S O N D
Sonoran Desert Native, great nectar plant, attracts native birds and super larval host plant:
Mexican Yellow (Eurema mexicana)
Mimosa Yellow (Eurema nise)
Reakirt’s Blue (Echinargus isola)
Marine Blue (Leptotes marina)
Hubbard’s Small Silkmoth (Sphingicampa hubbardi)
Tricolor Buckmoth (Hemileuca tricolor),
Black Witch Moth (Ascalapha odorata),
Owlet Moths (family Noctuidae)
Mesquite Stinger Flannel Moth (Norape tenera),
Naval Orange Worm Moth (Amyelois transitella)
Merry Melipotis Moth (Melipotis jucunda)
Common names include catclaw acacia, catclaw mesquite, Gregg’s catclaw, paradise flower, wait-a-minute bush, and wait-a-bit tree; these names mostly come from the fact that the tree has numerous hooked prickles with the shape and size of a cat‘s claw which tend to hook onto passers-by; the hooked person must stop (“wait a minute”) to remove the prickles carefully to avoid injury or shredded clothing.
The Cossidae, the cossid millers or carpenter millers, make up a family of mostly large miller moths. This family contains over 110 genera with almost 700 known species, and many more species await description. Carpenter millers are nocturnal Lepidoptera found worldwide, except the Southeast Asian subfamily Ratardinae, which is mostly active during the day.
This moth is found in California Arizona, New Mexico, and Colorado and most likely in pine forest areas of northern Mexico.
Larvae feed on outer bark of ponderosa pine. I couldn’t find a caterpillar picture in this genus on iNaturalist. Here’s an example of another species in Family Cossidae.
According to Wikipedia: Saturniinae is a subfamily of the family Saturniidae. They are commonly known as emperor moths or wild silk moths. They are easily spotted by the eyespots on the upper surface of their wings. Some exhibit realistic eye-like markings, whilst others have adapted the eyespots to form crescent moon or angular shapes or have lost their wing scales to create transparent windows. They are medium to very large moths, with adult wingspans ranging from 7.5 to 15 cm, in some cases even more. They consist of some of the largest sized Lepidoptera, such as the luna moth, atlas moth, and many more.
If you’re reading this from New Mexico, the Valle de Oro National Wildlife Refuge Grand Opening of Visitor Center and 10th Birthday is on Saturday, September 10th, about a month away. I hope you’ll join us!
I’ve dedicated more time to nocturnal critters this summer. It’s super rewarding to check the porch lights for moths and find a new one. So many cool insects hang out at night if you go and look.
There are plenty of diurnal critters too. Wasps (yes, wasps!) in all sizes and colors and a few new native bees for my yard list are among the highlights. It is lovely to sit outside with my camera, surrounded by nature. I enjoy watching bees collecting pollen, wasps hunting for a meal, and hummingbirds chasing each other.
Last Saturday marked our first significant monsoon rainfall, measuring in at 1″, and neighboring parks allow us to observe how the desert has responded.
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.
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.
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
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.
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.
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.
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.)
Monsoon continues through August. Average rainfall and nighttime lows are similar to July and average hours of sunshine fall by about 7%.
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.
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.
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!
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.
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.
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.