June predators

Where abundant prey grazes the earth, predators are not far behind. The tasty (and very numerous) aphids merrily sucking the juices off the marsh elder (Iva frutescens) prove irresistible to lady beetles and other visitors.

This is actually an introduced species, a famous (or infamous) Multicolored Asian lady beetle (Harmonia axyridis). Their color is very variable, and this particular form is spotless. The species was introduced in the US to control aphids and is still sold by some stores that offer "biological control". The adults can become a nuisance in the fall when they seek shelter inside houses for hibernation. The larvae (immatures) consume the most aphids, but handle with care, they bite!

With an aphid, back to back

Vegetarian "mosquitoes" of the salt marsh

There is a marsh insect that leads a mosquito-like lifestyle, but in a vegetarian fashion. Aptly named Draeculacephala, a Dracula-like headed leafhopper, he is a harmless fellow, at least to vertebrates. Like the mosquito, he sucks the fluid from inside a living thing, a plant. Like the mosquito, Draeculacephala leafhoppers transmit diseases, plant viruses, some of them fatal to the host. Like the mosquitoes whose bites can seriously hurt an animal if delivered en mass, large number of Draeculacephala can inhibit the growth of grass species they feed on by as much as 50%. Unlike the mosquito, both sexes of leafhoppers hunt for and derive their nourishment from plant juices (only female mosquitoes take blood strictly for egg production, and both sexes feed on nectar).

The tale of two invaders: the common reed and the mealy plum aphid

Common reed (Phragmates australis) has been conquering the salt and brackish marches of the East coast for over half a century. The plant form extensive stands densely covering all available marsh surface and leaving little room for anything else. Scientists discovered that the aggressive form of the common reed is actually an exotic plant introduced from Europe but closely related and almost indistinguishable from the native North American version. The European type outcompetes the native plant, partially due to another invasive passenger it brought along from the old country: Mealy Plum Aphid (Hyalopterus pruni).

 This little aphid sucks the plant juices causing leaf damage. When the aphid numbers are low, the injury is hardly visible.

However, when the aphid populations go up, the damage (such as leaf browning seen here) becomes more obvious. The problem is that mealy plum aphids prefer the native common reed over the introduced form, and reach much higher numbers on the native plants capable of killing them outright. The exotic invasive form of common reed is not as attractive harboring the aphids without extensive injury to the plant. This insect might be contributing to the invasive form takeover of the marshes by selectively weakening or destroying the native plants.

 Mealy plum aphids have two color types, green and red. The significance of this is unknown. 

Source: Lambert AM, Casagrande RA. Susceptibility of native and non-native common reed
to the non-native mealy plum aphid (Homoptera: Aphididae) in North America.
Environmental Entomology 36(2):451-7.

Marsh in monochrome

May - not by the flies alone...

Without a doubt, the little flies dominate the insect life of the salt marsh in the early to mid-spring. They hop the mudflats, skate the pools, and, swarm the salt marsh grasses. Being small and defenseless, they fall prey to numerous predators from fishes in the water to birds in the sky. Thus, they are trying very hard to complete their life-cycle before many voracious mouths arrive to their neck of the marsh either on wings from the south, or on fins from the estuary.

But, other insects are slowly making their way out of hibernation or popping from the eggs that spent their winter on the marsh. The juices are flowing in the young plants in May, and many herbivores love the tender shoots. Aphids, planthoppers, and true bugs use their elongated syringe like mouthparts to suck  the fresh sap. While this aphid is thus engaged in "milking" the Marsh Elder (Iva frutescens) rosettes, a tiny red "passenger" mite is happily obtaining its meal from the aphid. 

This shield bug is perfectly camouflaged to hide among the dead last season stalks of mixed salt marsh grasses and also sucks the sap out of the young plants

This conehead katydid nymph probably spent the winter on the marsh and now enjoying a snack of fresh salthay "salad". Unlike aphids and shield bugs, grasshopers, katydids and crickets chew their food.

 This gorgeous snout beetle or "true weevil" also feed entirely on plants. They chew holes in the plant tissue and contain some of the most important agricultural pests. Snout beetles are one of the largest group of animals on earth, with over 40,000 described species. For comparison, there are only about 6,000 species of mammals.

This small fellow is a shore bug (Saldidae spp). At a first glance, shore bugs might be easily confused with flies frolicking on a mudflat. They leap and take a short nervous flight as do many salt marsh flies. In fact, true bugs are not even fly relative, or perhaps 10th degree cousins removed. Shore bugs have a beak like all true bugs, and are either predacious or scavengers in the rich muck of the mudflats. Interestingly, these little creatures exhibit different degrees of adaptation to the marine environments - while some are found only on dry land, others remain on the marsh during the hide tide and become completely submerged by water.

The aquatics

Salt marsh pothole

The only place where truly aquatic insect life flourishes on a salt marsh is a small pool aka pothole. Mudflats hold too little water (but are a great habitat for various fly larvae wallowing in the soft ooze). Creeks, ponds, or ditches that hold water permanently or are flushed with the daily tides are off limits to aquatic insects due to voracious little predators, the salt marsh killifish.Potholes are something in between, either ephemeral or inaccessible by all but the highest tides. 





A pothole provides a home to an amazing array of shapes and forms - beetles, flies, true bugs, dragonflies, abd springtails. The omnivorous water boatmen (Trichocorixa verticalis)are the most ubiquitous denizens of that world eating both plants and little animal, and protected against fish predation by noxious excretions (like many other true bugs..) They might even outnumber the salt marsh mosquitoes...

Water boatman (Trichocorixa verticalis)

At the bottom of a pothole

A shore fly larvae (Ephydra subopaca) secretively hang around the pothole margins betraying their presence by the numerous shed skins remaining after molting into an adult. 

A soldier fly larva (Stratiomyidae sp) can grow to about  an inch long and is a peaceful filter feeder suspended almost motionless amid the calm water of the pool

A fierce but lazy predator (a water scavenger beetle, Tropisternus quadristriatus)  that is even larger stalks its prey, the mosquito larvae in this case, carefully

 

 While a more placid beetle cousin, Enochrus hamiltoni, feeds on detritus and organic matter

The little creatures such as the pupae of the biting midges (Ceratopogonidae) from the nonbiting genus Dasyhelea are visible to the discerning eye, and the surface is sometimes covered with little jumping dots, the springtail Anurida maritima

Dasyhelea pseudocincta pupal skin

Springtail (Anurida maritima)

A ferocious predators inhabits the depths of the salt marsh potholes.  The only truly marine dragonfly, Seaside dragonlet (Erythrodiplax berenice) devours mosquito larvae and other aquatic critters as an ugly baby "duckling" before turning into one of the most precious jewels of the salt marsh.