Green Drab Moth

If “drab” can be defined as “not interesting, plain, or dull”, then it seems the wrong adjective to describe this moth, Ophiusa tirhaca, which I find simply stunning in appearance.

But “drab” can also mean “a dull greyish to yellowish or light olive brown”, which I suppose is a more fitting description for the adult females of this species, pictured below.

Green Drabs belong to the Erebidae family of moths and are native to Europe, Africa, Australia, and parts of Asia. The adult female moths have brownish-colored forewings, with a darker, irregular-shaped, broad band along the bottom edge. There is a dark spot near the middle of the wing and a black mark about halfway along the front edge. Males have a similar pattern but the forewings are more greenish, or yellow in several of my observations.

The hindwings of both sexes are yellow with a broad, dark band near the bottom edge.

Ophiusa tirhaca larvae” by Sir Shurf is licensed under CC BY-SA 4.0.

Host plants include pistachio, pomegranate, sumac, and eucalyptus trees. Eggs are laid on trunks or older stems and the young larvae emerge and search for young leaves to feed on. Older caterpillars can be quite cryptic and difficult to see, resembling the branches they are attached to in shape and color.

Although the larvae might be a pest on some fruit trees, the adult moths are always a joy to spot!

Oleander Hawkmoth

The Oleander Hawkmoth (Daphnis nerii), aka the Army Green Hawkmoth, is the most magnificent moth I have seen in the wild. Look at those wings! The colors and designs are truly stunning. That’s why I was so excited last week when my husband called me over to point out the one he had spotted in our desert garden.

This species of hawkmoth is native to areas of Africa and Asia. They are a migratory species, however, and fly to parts of eastern and southern Europe during the summer months. Oleander Hawkmoths have also been introduced in many places around the world.

The larvae, or caterpillars, feed mainly on oleander bushes (Nerium oleander), which of course explains their common English name, as well as other plants in the dogbane family. These plants are highly toxic, but the caterpillars are immune. Oleander, which is not native to Sinai, is the most popular bush to plant along the streets in Dahab because of it’s toxicity. The goats and sheep roaming the streets of Assala typically won’t eat these bushes, so they one of the few that can survive in this part of town. And so there is plenty of food around in my neighborhood for these caterpillars to munch.

MMB_6870” by mmariomm is licensed under CC BY-NC-SA 2.0.

And if you thought the were amazing – check out these larvae! They are yellow when they hatch and turn green as they grow older. Like all hawkmoths, there is a “horn” protruding from the rear end of their body. There are large blue and white eyespots near the head (which are used as part of their defense system), a white band along the side of the body, and white and bluish dots. The caterpillar can grow up to 8.5 cm in length and turns brown shortly before it is ready to pupate.

Daphnis nerii” by acherontyus is licensed under CC BY-NC-ND 2.0.
Hawk moth caterpillar” by DocJ96 is licensed under CC BY-NC 2.0.

Fresh pupa are cream-colored but turn reddish-brown in color and will lie directly on the ground or under leaf litter.

Adult moths have a greenish head with a gray band at the vertex and a green thorax with a black/tan belt across the center. The forewings are patterned with green, whitish, and rosy-colored curved bands. At the base of these wings is a white patch with a black spot.

Adults drink the nectar from a variety of flowers and are especially active at twilight, just after sunset. Oleander Hawkmoths may be important pollinators, and can find themselves prey to birds, lizards, and bats.

Their life cycle, from egg-laying to adulthood, takes between 28 – 30 days.

Read about other hawkmoths in Sinai:

Convolvulus Hawkmoth (Agrius convolvuli)

Eastern Death’s Head Hawkmoth (Acherontia styx)

Striped Hawkmoth (Hyles livornica)

Dodder – A Parasitic Plant

The Cuscuta genus is the only parasitic genus in the Convolvulaceae, otherwise known as the bindweed or morning glory, family of plants. And Cuscuta species, commonly known as dodders, are the most well-known and widely spread example of stem holoparasitic plants. That’s right, these plants are obligate parasites. They do not contain chlorophyll and cannot, therefore, photosynthesize to make their own food. They must acquire the needed nutrients and water from their host plants.

Folk names, in English, for plants in this genus include wizard’s net, devil’s ringlet, strangleweed, and witch’s hair, to name just a few. I love the imagery of these terms! And once you’ve seen this plant in action, you realize these are great descriptions of these plants that climb, scramble over, and entwine themselves on their host plants with their slender, thread-like stems.

And it is from these many stems that grow haustoria, specialized tube-like growths that insert themselves into the vascular system of the host plants. This allows the dodder to absorb nutrients and water, and therefore grow and attach itself to multiple plants.

Because the plant does not photosynthesize, there is not much need for leaves, and so the leaves on dodder are very tiny scales. The stems range in color from reddish to yellowish. The small flowers are white, yellow, or cream colored and always hermaphrodites. The stems coil in a counter-clockwise direction.

The parasitic dodder seedlings can germinate and sprout but need to find a host plant quickly, usually within 5 – 10 days, or they will die. They have therefore adapted to use chemosensory, or an ability to sense chemical signals, to grow towards nearby plants. Until they are able to reach a host plant to parasitize, they rely on the food stored in the seed.

Dodder is parasitic on dwarf shrubs, herbs, and grasses and prefers soil with low salinity. We came across dodder in the small oasis of Um Saida (pictured below), near Wadi Kid. The dodder was growing across shrubs of Fagonia sp. as well as herbs such as wild mustard, or jahag (Diplotaxis acris). The dodder was tangled and growing over many plants, clearly illustrating how this could become a problem if the plants parasitize agricultural crops.

There are three species of dodder found in Sinai: Cuscuta palaestina (Palestinian Dodder), C. planiflora (Flat-flowered or Small-Seeded Alfafa Dodder), and C. campestris (Field Dodder). Although Cuscuta species have a rich history of traditional uses in folk medicine around the world, I came across no recorded uses in Sinai in any of the research I was able to access. I am curious to speak with more Bedouin who are familiar with the dodder growing in Sinai.

Eastern Death’s Head Hawkmoth

These beautiful wings above belong to a hawkmoth – specifically, to an Eastern Death’s Head Hawkmoth (Acherontia styx). Hawkmoths (family Sphingidae) are known for their sustained and agile flying abilities, reminiscent of a hummingbird’s flight and giving rise to another common name, hummingbird moths. There are 12 species of hawkmoths in Egypt. (You can read about two others on the blog – the Convolvulus Hawkmoth and the Striped Hawkmoth). Like all hawkmoths, the Eastern Death’s Head Hawkmoth has narrow wings and a streamlined abdomen, aiding their fast flying.

Acherontia styx is also known as the Small or Lesser Death’s Head Hawkmoth. Globally, there are three species of Death’s Head Hawkmoths (Acherontia spp.), all named in reference to Greek myths of death. A. styx is named after one of the rivers that divides Earth from the underworld. The moths were given this name in reference to the skull-like markings, with two black spots for eyes, on the back of the thoraxes, in addition to their somewhat-gloomy coloring.

Adults have brown heads, dark thoraxes, and a yellow-striped abdomen. Their forewings are mottled brown, grey, and a reddish color. The hind wings are yellow with two black bands. Eastern Death’s Head Hawkmoths have a wingspan of 80 – 120 mm.

Eggs are laid, and the larvae (caterpillars) feed, on a range of plants – potato, aubergine, tomato, tobacco, olive, as well as Capsicum, Solanum, Datura, and Nicotiana species. The larvae are yellow/green with yellow lateral stripes and go through several instars. When mature, they dig under the soil to pupate.

And these critters get more interesting!

Death’s Head Hawkmoths can, if disturbed, rapidly expel air to emit a loud squeak, similar to that of an agitated mouse. And these hawkmoths are also known as bee moths because of their ability to safely enter bee hives and drink the honey. They do this with the use of a chemical camouflage; they mimic the scent of bees.

Another fun fact: A. styx was featured in the film The Silence of the Lambs. (A victim was found with a pupa of this moth in her windpipe and there is a scene with entomologists determining the species.)

Interestingly, Acherontia styx was, in a study published in 2022, a new record in Egypt. The previous study on Sphingidae moths in Egypt was completed in 2005.

References:

Abdelfattah Mabrouk Amer Salem. Lepidoptera of Egypt Part III: Revision of Family Sphingidae (Bombycoidea). American Journal of Entomology. Vol. 6, No. 1, 2022, pp. 7-13. doi: 10.11648/j.aje.20220601.12

Specimen of the Week 194: The Death’s-Head Hawkmoth

Blister Beetles

These colorful insects belong to the Meloidae family of beetles and are commonly known as blister beetles. There are around 3,000 different species of blister beetles worldwide, and 145 species known in Egypt. They earned their common name from their defense mechanism – a secretion of a blistering agent, cantharidin. Getting this on your skin would cause an irritating reaction, but cantharidin is also used medicinally to remove warts.

Like all beetles (Order Coleoptera), they have hardened front wings that meet in a straight line in the center of their backs. Meloids, or blister beetles, are elongate in shape and the sides of their body are parallel. The pronotum, the hard shield-like covering on their thorax, is usually narrower than the head, and the tarsal claws are split in two lengthwise. Blister beetles are often conspicuous, with outstanding and noticeable colors. This announces their toxicity to potential predators.

Blister beetles lay their eggs in masses under stones, in the ground, or on the food plants of the adults. The larvae are insectivorous and are predators of grasshopper eggs and immature bees that they consume after entering the nests. Adults can live three months or more and feed on the nectar and pollen of a diverse range of plants – from the amaranth, aster, legume, and nightshade families. Some blister beetles also feed on foliage, leaves, and flowers and can be destructive to gardens and crops. In Egypt, for example, Meloe rugosus is a pest on agricultural crops in the western desert and feeds on fava bean, wheat, peas, alfafa, and onion plants.

Adult blister beetles are seldom seen. Have you ever spotted one while wandering through wadis in South Sinai?

Desert Skimmer

Widespread in Africa and the Middle East, the Desert Skimmer (Orthetrum ransonnetii) is mostly found in hot, arid, rocky environments, like Sinai’s desert mountain region.

These dragonflies have almost completely black venation and completely transparent wings. (There is no amber color on the hind wings like in other species.) The males are blue, with an unwaisted body, and females are brown.

Because their larvae and nymphs are aquatic, Desert Skimmers are common at small flowing and standing pools of water, and particularly areas without a lot of vegetation.

Desert Skimmers are known to hang from vertical or sub-vertical rocks and walls. And if the weather is hot, they especially like to hang in shaded places.

Dragonflies are carnivorous, predatory insects, hunting on the wing for other flying insects, including mosquitoes, flies, butterflies and moths, and even smaller dragonflies. Their acute eyesight and strong, agile flight help make them some of the world’s most efficient hunters. Dragonflies catch up to 95% of the prey they pursue. And that’s good, because a dragonfly eats up to 1/5 of its weight every day.

Bedouin in Sinai, at least of the Jebeleya tribe, call a dragonfly a ghizlan غِزْلان

What do you call them in your native language?

Be sure to read the post about the Violet Dropwing where you can learn more about dragonflies’ amazing wings!

Pearl Plant

The distinctive yellow flower stalks and the pearl-like fruit of this desert shrub make it easy to recognize and remember. The pearl plant (Ochradenus baccatus) is quite common in the region and are spotted often on my wanders in the wadis near Dahab. In the springtime, they are buzzing with flying insects – bees, wasps, flies, hover flies, beetles, and more I’m sure. This shrub has been reported as one of the most important food sources for many animal species.

There’s one species in particular that the plant has a special relationship with – the Egyptian spiny mouse (Acomys cahirinus). The fruit – a fleshy, juicy berry – is attractive to desert animals. But when an enzyme in the flesh of the berries combines with what’s inside the seed, it creates a toxic “mustard oil bomb”, deterring most animals from munching on this fruit (and destroying the seeds in the process). The spiny mouse has adapted to this, however. They will collect fruits and bring them to a different, rocky area, one that is safer for them. There, the mice chew and eat the flesh, careful not to bite the seed which they then spit out, avoiding any nastiness and helping to disperse the plant’s seeds. One study suggests these safer places the mice choose are actually “the best places for young O. baccatus plants to germinate, grow and survive.” How’s that for some symbiotic behavior!

The Bedouin of Sinai have also found benefits of the pearl plant, using it in traditional medicine to cure joint pain. A bowl of water in which the leaves have been boiled is placed in a hole in the ground above which a makeshift tent is constructed. The patient then lies beneath its cover for 24 hours. Pearl plant is also used to cure aches and pains in a camel’s body except instead of boiling the leaves, the plant is placed on embers in a hole. In Saudi Arabia, the plant is used to lower blood cholesterol and to counteract malaria.

Recently, a friend and fellow plant-lover asked me if this species had separate male and female plants as she had noticed that some plants were full of berries, while others only had a few. In dioecious plants, only the plants that grow female flowers produce fruit. Date palms are a good example. It turns out, though, that the pearl plant is gynodioecious, meaning that some plants have only female flowers and some plants are bisexual, having both male and female flowers. This explains the phenomenon my friend noticed – two plants, side by side, both in full bloom but only one seeming to fruit fully.

I’ve always liked this plant’s Latin name, Ochradenus baccatus. Ochradenus comes from the Greek for “pale yellow” or “yellow ochre”, and baccatus means “adorned with berries”. It is also known as taily weed and shrubby or sweet mignonette in English and is called gurdhi by the Bedouin in South Sinai.

References:

Bailey, C., & Danin, A. (1981). Bedouin plant utilization in the Sinai and the Negev. Economic Botany, 35(2), 145–162.

K.C. Burns. Seed Dispersal: The Blind Bomb Maker. Current Biology, Volume 22 (Issue 13), 2012, Pages R535-R537. https://doi.org/10.1016/j.cub.2012.05.014.

White-crowned Black Wheatear

If you are wandering through wadis in South Sinai, it is almost guaranteed that you will see, or at least hear, a White-crowned Black Wheatear (Oenanthe leucopyga). They are resident in the rocky deserts and common around settlements and oases. The Bedouin call these birds baqa’a’ بَجَعاء

Adult birds’ approximate length, from the tip of the bill to the end of the tail, is 17 cm. They are mostly black, with a white crown, rump, and tail. Juveniles, and sometimes females, have a black crown, as seen below.

Wheatears are passerine birds. Birds in this order are sometimes called songbirds or perching birds. Their toes are arranged in such a way, three pointing forward and one backward, that facilitates perching. Wheateats eat mainly insects and have a loud, varied song. One book, Birds of Eastern Africa, describes the song as “high, loud, happy, short, fast whistles”. I think they definitely have a beautiful song. Have a listen. How would you describe it?

Tero Linjama, XC341760. Accessible at www.xeno-canto.org/341760

According to the authors of Gardens of a Sacred Landscape: Bedouin Heritage and Natural History in the High Mountains of Sinai,

White-crowned Black Wheatears build their nest in three stages. Small smooth rocks are placed in front of the nest to prevent snakes from entering (or, according to one informant, to warn of a snake’s presence by the noise of their disturbance). The nest is then covered with small stones, and finally the nest is layered with twigs. The birds are present all year long in wadis and around houses, feeding on insects (including ants and spiders); one Bedouin told us that in summer they also feed on black grapes. They often become very tame, and are welcomed by Bedouin as one of the ‘birds of happiness.’

Zalat and Gilbert (2008)

Seeing and hearing them in the wadis definitely adds some happiness to my wanders!

Ashwagandha

I had already published the third edition of Wandering through Wadis when, last April, we came across several plants in Wadi Kid that we’d never seen before in the wild. Ashwagandha was one of them.

Ashwagandha is a well-known plant and is one of many names given to Withania somnifera, which grows here in Sinai. There is a related species that is also native to the area – Withania obtusifolia. To complicate matters a bit, there seems to be have been some debate recently as to whether W. obtusifolia should be classified as a subspecies of W. somnifera. Which exact species I have photographed here is a mystery to me, but let’s learn about ashwagandha.

Withania is a genus of plants in the nightshade family. Of the 23 species, two – including W. somnifera – are considered economically important and are cultivated in various regions around the world for medicinal uses. In Ayurveda medicine, ashwagandha is used as a medicinal herb and dietary supplement. Other names for W. somnifera include Indian ginseng, poison gooseberry, and winter cherry…but I’ll stick to using ashwagandha (until I can confirm the Arabic name).

Ashwagandha is a drought-tolerant evergreen shrub that grows in dry, stony soil and can grow to be between 35 and 75 cm tall. The branches are hairy and grow out radially from the central stem. The leaves are dull green, generally egg-shaped, and 10 – 12 cm long. The flowers are small, green, bell-shaped and grow in clusters; the ripe fruit is orange-red.

Sadly, a 2020 article in the Egyptian Journal of Botany reports that of the 8 threats the authors categorized plants as facing, Withania somnifera is subject to seven: over-collecting; habitat loss; clearance for agriculture, mining and quarrying; disturbance by cars and trampling; urbanization; tourism; and climatic change and environmental conditions. Even though ashwagandha is apparently a common plant in Egypt, after reading that list of threats, I feel lucky to have come across these plants in the wild. I had seen them before as my husband had them growing in his permaculture garden. He tells me that ashwagandha seems popular with Egyptian gardeners and farmers these days. Have you come across ashwagandha in your wadi wanderings? Or have it growing in your garden?

Leaf Morphology: Arrangement

Since my guidebook was intended for nature-lovers, not necessarily plant specialists, I took care to define and explain the technical terms used in the descriptions of the plants in my book, choosing simpler English synonyms when possible. But it’s not always possible. So I thought it might be helpful to dedicate a few blog posts to delving into some of these technical terms a bit more, deepening our understanding and looking at some specific examples from our desert plants. And I thought I’d start with the terms used in leaf morphology.

In botany, morphology is the study of the size, shape, and structure of plants. Plant biologists use these characteristics for the descriptions, classification, and identification of plants. Having some understanding of these different characteristics will help you to recognize and identify the plants you see while wandering through wadis.

In leaf morphology, one of the key characters studied is leaf arrangement, the number and placement of leaves along the stems. This arrangement of leaves is called phyllotaxy and we’ll talk today about four general categories – alternate, opposite, whorled, and rosette – although there are various levels and ways of categorizing these patterns.

Leaf morphology (Debivort) CC BY-SA 3.0

A node is the point where the leaf emerges from a stem or twig, and arrangement is always regular.

In the alternate pattern, sometimes called spiral, each leaf or leaflet grows from a different node.

In the opposite arrangement, two leaves or leaflets grow per node, on opposite sides of the stem.

If, in this opposite pattern, the successive leaf pairs grow at right angles, it is called decussate. These perpendicular pairs of leaves are typical of plants in the mint (Lamiaceae) family, like the ones pictured below.

In the whorled arrangement, three or more leaves or leaflets are connected at one node. Blepharis attentuata, pictured below, grows whorls of four leaves.

When the leaves of the plant emerge from the base in a whorled arrangement, spreading out in a circle, it is called a rosette.

Understanding the various patterns of leaf arrangement will help you to understand plant descriptions that you read in my book and other sources. And if you come across a plant you do not know, take note of its leaf arrangement (Photos are a great way to document this.) because it could be an important characteristic to consider when identifying the plant. In the next few posts, we’ll learn about other key characters in leaf morphology that will help us identify the plants.

One of my favorite desert plants is the caper bush; its leaves grow in an alternate pattern. I also love germander (Teucrium sp), both for its delicious fragrance and its neat geometrical leaf pattern. Do you recognize these leaf patterns in any of your favorite desert plants?