Saturday, April 11, 2015

Arthropods as builders

Construction projects of the arthropod world: They may be shelters, nurseries, traps for prey, or 'greenhouses' for farming, storage facilities, even floating devices - Arthropods can produce the most amazingly complex and functional structures. To complete those, they may work alone or together with hive members, building with hard labor or by chemically stimulating a host organism to do the work. Structures may be built for duration or destroyed and rebuilt every 24 hours. They may be built for a special event in a life cycle of the insect or for everyday needs.


Many ants build nest mounds. In Germany I often saw huge piles of material containing chambers that contained different stages of larval and pupal development - nurseries that would be moved around within by workers when the temperature changed (Rote Waldameise (Formica rufa)). In other species, piles of soil seem to be just material that is moved out from underground chambers, or refuse that is piled around the entrance of a nest. But the structures that our local leafcutter ant Acromyrmex versicolor builds seem much too well designed to be just piles of refuse. They are perfectly round cones with a crater-like opening when they are new. They erode later, but are often restored. Most colonies have several of these structures. These ants are fungus growers. Their activity level varies very much with season and weather. I assume that they have ways to regulate the growth rate of their fungus gardens in correlation to their own activity level, and I believe that those cones are actually chimneys that control the ventilation of those underground gardens. Either they need more ventilation during high growing seasons, or the ants can even promote faster growth by building higher (or more) chimneys.



 Termites in Africa and Australia build long lasting tall structures, but our Desert Encrusters only work on their adobe structures when the weather is just right after the monsoon rains. They completely cloak dead wood with a layer of mud under which they are protected from the sun while they are slowly rasping away the top layer of dead plant material. Even scar tissue on saguaros gets this treatment. Living tissues are not harmed. Their relatives, the feared subterranean termites, are constructing tell-tale mud tubes to get safely to their deconstruction sites - a thing to be aware of. Some of our termites also build mud turrets as launching platforms for their alates. Every summer, those winged, sexual specimens are waiting within the colony, ready to swarm under just the right weather conditions. When those are perfect, the workers literally push the alates out of those turrets to take flight.



Other mud tubes are the nests of Organ Pipe Mud Daubers. These sphecid Wasps  catch and paralyze spiders as provision for eggs that are placed in rows of chambers covered in mud. These are from Sonora Mexico and were located in a protected spot under an overhanging rock formation.  

Anthidiellum sp., Resin bee, nests, Megachilidae
 Flowers need to seduce insects to visit and pollinate, and the reward is not always nectar. Some flowers offer building materials to their pollinators, for example resin to some species in the family Megachilidae. Female Resin Bees attach single cell nurseries to twigs, some even work little pebbles into the structure.    

Wasps and Hornets developed paper long before even the Chinese knew about it. Chewing cellulose and lignin rich plant material, the insects produce an extremely light and durable building material. Series of hexagonal cells can be tightly packed, forming  structurally sound and expandable mass nurseries and storage chambers. In many cases a thin stylus supports hundreds of cells. The wax honey combs of bees are much heavier, so their builders usually fit them into preexisting niches and cavities.  


 Here in AZ a little Eurasian weevil Coniatus spendidulus is taking on the rapidly spreading tamarisk bush, also from Eurasia. It is not clear whether it was released on purpose or not and it seems to be far less destructive to this botanical pest than some leaf beetles that were introduced. But the tiny guys are interesting in that they have larvae and pupae on the plant surface and do not go into the ground to metamorphose. Instead the last instar larva builds this cage-like cocoon and pupates inside. The whole fragile thing is barely 2 mm long, so I do not know how it protects the pupa, except from falling off the twig.
 


Leaf-rolling Weevils (family Attelabidae) lay their eggs on oak or Hazel, Alder etc. leaves. The female then cuts the leaf and rolls it very tightly, preserving the mid-rib. The larva lives and develops in the 'nidus' that is formed. But when I collected some, a different, related weevil, the Thief Weevil, hatched. This beetle crawl carefully into the fresh nidus and replace the original egg with her own. So the brown weevil Himatolabus pubescens is the constructor and the blue one, Pterocolus ovatus. is the thief. Did I mention that the thief is a cousin in the same family Attelabidae?
Madera Canyon, April when the oak leaves are fresh


 Many caterpillars use their silk glands to spin protective tubes or pull leaves together as a shelter. But the communal nests of some Tent Caterpillars (Malacosoma) stand out for their in size and strength. In the image you see that the caterpillars enlarged  the nest repeatedly as they grew from tiny hatchlings to 2 in caterpillars. They spend nights and periods of cold weather inside. The metabolism of the caterpillars and their accumulated droppings produce heat. The toughness of the silk walls and shed urticating hairs keep many predators out. But some warblers learn to pick up any caterpillars that venture to the outside. And they need to come out to feed. When they do so, they leave silk strands along their path to guide them back to safety later. Scouts seem to lead the way. The caterpillars can defoliate young wild cherry trees, aspen or willows, but usually the trees will not be harmed permanently. I have collected tent caterpillars for a project and 80% yielded parasitic tachinid flies instead of moths.




:The tiger moth Euchaetes elegans lays her eggs on host milkweeds and covers them with the bright white scales from her belly. I presume this helps protect them from parasites, predation and perhaps the weather, but does nothing to hide them. The mature larva also incorporates hairs into its cocoon. The larva, however, is covered in black, orange and a few white hairs so the cocoon looks nothing like the egg mass. Here in Tucson you can find all stages of this insect during the monsoons, when climbing milkweeds are abundant. Images and text contributed by Randy Hardy


We have moths but also beetles that are called 'case bearer' because their larvae build little covers that they carry around. Our Warty Leaf Beetles look like caterpillar droppings as adults, but their larvae carry these little magician hats. The material is probably feces as in the protective shields of many leaf beetle larvae, plus plant fibers it seems.

Snailcase Bagworm (Apterona helicoidella) and Oiketicus sp.
 Psychidae (Bagworm Moths) Larvae (bagworms) construct snailcase or spindle-shaped bags covered with pieces of twigs, leaves, etc., and remain in them enlarging the bags as they grow -- until they pupate (also in the bag). Adult females remain in the bag even then, emitting pheromones which attract adult males to mate with them. The wingless female then lays her eggs in the protection of the bag.



Plant gall inducers:
Insects of several different orders like hymenoptera and diptera and hemiptera have developed the ability to induce host plants to generate extra tissues especially for their use: plant galls. Unlike tumors, they grow into a very specific shape in a specific place. On the same oak you can find stem and leaf galls, round ones that are smooth and woody and others patterned like marbles or fuzzy like little animals. Most contain a developing insect but some, like the stem galls on Cottonwood, contain a whole colony of aphids.


My friend Jim Zimmermann devoted decades of his retirement to the collection of oak galls in Arizona. He cataloged the host plant and the insects that hatched - often not just the insect that induced the gall to grow (mostly wasps), but also parasites that also used the gall tissue and others that used the  larva of the gall wasp as their host. Secondary parasites of those made the system even more complex. He donated the whole incredible collection to the U of A insect collection and still spends many hours every week working on it and other hymenoptera groups.

Froth produced by a spittlebug nymph, lower right.
Not a yet a permanent,  hard construction (but some relatives of spittlebugs build something similar that calcifies)...
Spittlebug nymphs, like all hemipterans, suck plant juices. Like other plant suckers, they take up much more sap than they need and have to get rid of the excess. While aphids just excrete honey dew and sharp shooters eliminate it in sudden bursts (shots) Spittlebug larvae  produce a blob of foam. It  protects the tender larva from dehydration and overheating, and hides it from parasites and predators.
I always assumed that the froth is very distasteful, wikipedia says acrid ... until one day I noticed that on certain Seepwillows (Baccharis salcilifolia) every blob of spittle had a guest: Paper wasps, flies, and even a teneb beetle were peacefully licking up fluid under the spittle. But they did not attack the nymph inside.



Most of the constructions mentioned so far have been shelters, but some of the  most amazing achievements of all seem to me the webs of spiders. Structures that often combine the functions of shelter and trap. From trip lines to funnel shapes, to wheel like webs with regular spokes, to huge communal hammocks - many different types of web can be produced. The material is released by spinnerets under the spiders's abdomen. The strands can be made for strength or stickiness or even extra light, to allow the spider to float through the air with it. Pictured is the web of a Cribellate Orb Weavers genus Uloborus. The cribellate threads are electro-static, but not sticky.


Build in sand:
Certain antlion larvae dig pits in loose sand to use as traps to catch their prey. They sit buried to their mandibles at the bottom. When ants walk across the pit they lose traction and slide down into the center where the hunter awaits them. If an ant seems likely to escape, the lion tosses sand at it to cause an avalanche that will bring it down.

Construction was a topic that Robyn Waayers proposed as the weekly theme for our insect group on FB. I was going to simply collect my contributions here, but then it just kept growing .... I still have many more ideas, but this blog is too long already






Monday, March 30, 2015

Parental Care among Arthropods


You may think that insects are not really good at it while many arachnids are better. But, as long as the offspring survives it’s probably just exactly the amount of care that’s necessary. In many cases the short-lived parental generation is not around to see the eggs hatch anyway. So the care may all be in the careful placement of the eggs on exactly the right food plant or in the protective microclimate of a nest or at the best spot to hitch a ride with the best foster parents …. Or the care may involve tackling a scary giant as a host or a smelly pile of dung rolled into appetizing portions … 

Canthon imitator, Rio Rico, Santa Cruz Co, AZ
 Some dung beetles are 'tumble bugs'. Using their shovel-shaped heads a pair cuts a round ball out of a fresh pile of dung. Then they roll their prize a considerable distance from its origin, bury it, and the female lays eggs inside it. In some species, the parents stay around to protect and feed the offspring while the larvae grow in their dung ball. Why don't the beetles just drop eggs into the fresh dung and leave? Some flies do it that way? That's just it: dung of big vertebrates still contains many nutrients in a very accessible form, so the competition is great. Beetles, flies, worms, all claim their share. Large dung beetles develop more slowly than many smaller competitors. Also, dung attracts predators. So these parents grab there share and then set up house as far away from the source as possible.

Oncideres rhodosticta (Mesquite Girdler)
 Many wood-boring insects have to deal with the trees self-defense mechanisms. If the larvae are feeding in living parts of the tree they are likely to be gummed up by an avalanche of sticky tree sap. That is the reason why bark beetles are so dangerous during droughts: the tree does not have enough sap to spare to fight back.
In Arizona, we have several longhorn beetles whose larvae grow up in twigs. They are rather host specific, so one uses oaks, another species specializes on mesquite and close relatives.  To guarantee the safety of the larvae, the female chews a grove around the twig, all the way through the cambium to interrupt sugar and water transporting vessels. Often a big glob of accumulated sap can be seen on the tree-side of the cut. But the apical part of the twig is now wilting and dying and defenseless.  That's where the beetle is placing her eggs and where the larvae will grow up. Several other species of insects that are usually drawn to freshly dead wood also find those dying branches. So if you collect those dead branches in a raising box you will usually find a number of different insects emerging.

Melanophila consputa
Freshly dead wood is at a premium for the larvae of wood-boring beetles. Adults of a number of species can be found at wood cuttings or wind breaks where they mate and deposit their eggs. A special situation are trees killed by forest fires.   Buprestids in the genus Melanophila  have pits on the mesosternum that actually detect fires. The females are so drawn to this wood that they may come too close to the fire and burn off their tarsi (feet) while ovipositing.

Neuroctenus sp. with offspring, Santa Rita Mts.
Many true bugs stay with their brood and take care of them.. I still remember hearing recordings of acoustic communication between stink bug mothers and their offspring at the University of Ljubljana when I visited the physiology department there in 1981. It was a squeaking sound that she seemed to  generate by stridulating her proboscis in its grove. The kids were quite obedient, they dispersed at one signal and clustered under mom at another. My photo shows a bug from a different family, a Flat Bug (Aradidae) with very young nymphs and eggs



Our Uloborus spiders live indoors with us. They are pretty safe from most predators and, I must admit, from my dusting as well. But they multiply! They build starshaped eggsacks that hang in their cribellate webs until they suddenly burst into fluffy cotton balls, releasing dozens of miniature spiders. Mom allows them to live in her web for a while and then they build their own ones close to hers. So eventually I will have to oust them ..



Spiders often guard eggs and hatchlings in their webs. But few wolf spiders have webs to call home and they need to get around to hunt. These ambulant species have a characteristic way of lugging their egg-sack around under their abdomen. When the young hatch they climb on mom's back for a wile. I would love to see the mother catch prey. I assume the kids get to eat then, too.
By the way, wolf spiders have a good reason to be vigilant. Wasp Mantisflies are waiting to get their own eggs into that egg-sac ...



Brood parasites wait for every tasty clutch of eggs and even more so for eggs that come provisioned with food. So many eggs are deposited deep within nests which are hidden and sealed. Here a Leafcutter Bee is choosing the wall paper for her nursery. Her nest is in a pre-existing hole, maybe a hole from which a wood-boring beetle has hatched. She covers the walls with her circular cut-outs and she uses them to separate the tunnel into several cells. Each will hold provisions (pollen) and an egg. Males develop faster, so those eggs are placed closer to the exit than those that will become females. Leaves may provide moisture and insulation, but most importantly they have some antifungal and antiseptic qualities that may protect the pollen and the egg.

Polistes major castaneicolor, Queen with 2 workers
 More sophisticated than most other care systems is that of the social hymenoptera. A queen (or several) starts the nest in spring. After she's raised a few new workers, she's got help and can concentrate on her main role: to lay more eggs. The larvae will be tended by the workers, who are their sisters. These females need not reproduce themselves because they share at least as many genes with these larvae as they would with their own offspring.
In Arizona I have always seen dark brown Polistes major castaneicolor. But in early spring I found some solitary wasps that I could not fit into any of our Polistes species. Now I see one of them on each of the new nests, in this case accompanied by 2 of the 'castanaeicolor' individuals. I'm guessing that those are the first daughters of the young queen and hatched from the two cells in the center that contain no eggs. New cells are added on the periphery, so those are younger. You can see the eggs inside. If only the overwintered queen is banded in yellow and rust, it's no wonder that I thought that ALL P. major castaneicolor are brown.


Tuesday, March 17, 2015

Mating behaviors among bugs

While sorting the slides for my first ever public talk, a presentation about insects in our local forest in Westphalia, Germany, I found that about 75% of my more interesting photos showed insects in some kind of sexual activity. I was 17, my audience mostly older gentlemen from the local zoological society, and I felt somewhat embarrassed. I got over it and the talk was a success. And think about it: Adult insects, stuck in their stiff exoskeleton...s, aren’t exhibiting too many visually impressive behaviors. They eat or get eaten, or try very hard not to, and they mate and lay eggs. But mating may involve calling, scenting, lekking, courtship and pursuit, dancing and rejection, rape, gift giving, copulating, decapitating, mate guarding …. There is plenty to observe and photograph. And even the most flighty Tiger Beetles tend to slow down for a while … 

Lucaina marginata and Lucaina discoidalis, two species of net-winged beetles
 For animals that do not live in social groups, finding an appropriate partner is the most important part of mating. Pheromones released by one partner may stimulate extremely sensitive olfactory organs of the other gender - and matches are made.
When the Mesquite trees are blooming in the Tucson Mountains I sometimes find the catkins of single trees covered in net-wing beetles. They are nearly all mating pairs. They probably attract each other through pheromones. But there are usually beetles of 2 different species present. Pheromones of closely related species can be similar or identical, so there must be an additional process of mate recognition to match up the correct partners. Lycids are loaded with toxins, so these aggregations may not only allow the beetles to find mates but also protect them against predation.


Collops sp., Melyridae (Soft-winged Flower Beetles), Montosa Canyon, October
Antennae of most insects are the site of incredibly sensitive chemoreceptors but in Melyridae (Soft-winged Flower Beetles), the male's antennae carry big, lumpy extensions. You can see them on the right beetle. Those are not receptors, but producers of stimulating chemicals. On this occasion he was waving them at her, stroking her antennae, doing a whole dance of seduction with them, but she still rejected his advances in the end.

Leaf Beetles Deloyala lecontii
Most biologists define a species as a group of genetically similar individuals that can produce viable offspring by mating under natural conditions. Several beetles in Arizona appear in drastically different color morphs. But they are definitely conspecific because they mate and produce offspring indiscriminately of their color morph.   

Trichodes ornatus (Ornate Checkered Beetle)
Trichodes ornatus (Ornate Checkered Beetle) can sport contrasting black bands on bright yellow or deep red elytra.. Yellow/black may be wasp mimicry while the red/black ones closely resemble a species of blister beetles that occurs on the same flowers where the checkered beetles find their mates.  The threesome in the picture shows a female on the right and 2 males on the left, so the color is by no means gender specific.


Approaching a female can be risky for males of aggressive predatory species that are used to taking prey that is hardly smaller than they themselves. Several groups of diptera (flies) have developed ritualized gift-giving which appeases the female. I am not aware that these big Robberflies actually do that, but this male did successfully grab his chance while the female was busy feeding on a Yellow Jacket.

Desert Firetail pair mating in wheel position
Dragons and Damsel males have secondary sexual organs.
Prior to mating, the male moves sperm from his primary genitalia at the end of his abdomen to the middle of his body where he stores it in a secondary genital location. When he finds a female he grabs her neck/head/eyes with his claspers. Tandem position. She then reaches forward to position her cloaca against his secondary genital opening to receive the sperm. Their bodies now form the mating wheel. 


Hetaerina americana (American Rubyspot
After mating the two may stay together in the tandem position while she lays her eggs. This is mate guarding (against other males) but also allows the female to submerse herself to position the eggs under water while the male hovers above to pull he up.

Leaf-cutter Bees
When I saw the bees swarming a fence post at the Arizona Desert Museum I thought at first that I had found the hive of a social species. But they seemed too frenzied for worker bees. They turned out to be male Leaf-cutter bees waiting for females.
Leaf-cutter bees are solitary, but a good nesting site with many deep tunnels (beetle holes) may attract many females. Each lays multiple eggs in those tunnels, eggs that will become females are placed deeper inside, prospective males more towards the tunnel entrance. The males hatch first. Then they hang around the entrance, waiting for the females to hatch. No matter that some will be their sisters. On thing is certain: no female will run this gauntlet and leave a virgin.


Honey Bees, Apis melifera
Among social bees, only the young queens and few lucky drones mate. A young queen mates only once. She takes off with a part of the old hive's workers to start a new hive. There she will produce thousands of eggs from this one mating.
While the bees are swarming and traveling to a new location they often rest in the open, all clustered tightly around the queen. At this stage the crops of the workers are full of stored honey and they lack aggression. The swarm I found was very small, which might indicate that these were Africanized bees, but I could approach closely without problems.
Drones (males) are recognizable by their large size and their big eyes - I have focused in on one in the right photo. Drones do not forage and don't get fed after the mating flight, so at times they can be found dying under the hive. This is no indication that anything is wrong with the hive in general.


Acromyrmex versicolor pair
 Leafcutter Ant colonies release swarms of winged males and females after generous monsoon rains in late summer. Clouds of alates hover like smoke columns over the nest exits. Young Acromyrmex versicolor queens mate with small-headed males in the air and tumble to the ground together. They lose their wings and the males die soon after. The queens are carrying the beginning of a new fungal garden in their crops with them. Several of them may start a new colony together.


 While scouting in preparation for the BugGuide Gathering in 2013, I was caught in a July thunderstorm in Florida Canyon, Pima Co, AZ. Suddenly many insects were flying in the soft warm rain, most of them tumbling to the ground. There they quickly shed their wings and began running around in pairs. Soon predators like ants an birds began picking them up. But many couples escaped to find new underground nesting sites to begin a new huge family of Termites. Different from ants, wasps and bees, they will have a long fertile life as a couple ahead of them. 

Colliuris pensylvanica, carabids, and Anomola delicate, scarabs
 And what do bugs do instead of on-line dating? Black light dating! Always available during the monsoon months in Arizona and highly recommended ....   








Wednesday, February 18, 2015

Aquatic Arthropods in Arizona

Of course, arid Arizona does not seem to be the very best place to look for aquatic life in any form. But we do have a few riparian areas left, some permanent creeks and cienegas, some artificial lakes, artesian ponds, rivers that carry mostly treated waste-water and of course many temporarily flooded areas during a good monsoon season. But where there is water even temporarily, there are always many interesting creatures.

Laccophilus pictus coccinelloides, Sabino Creek, Pima Co, AZ  4-4-2012
Predaceous Diving Beetles (Dytiscidae) were always among my favorite aquatic insects. As a kid in Germany, I used to raise the huge, fiercely predatory larvae of Dytiscus marginalis, one of our largest beetles. But here in AZ I came to appreciate also the beauty of some of the smallest members of this family. Although so prettily patterned, these 4 mm long, fast swimmers are nearly invisible in the tannin-colored water and against the mica glittering sand of Sabino Creek.
 Note the air bubble that is held under the elytra. When the beetle has used up oxygen from the original air, fresh oxygen diffuses from the water into the bubble. It's a physical gill. From time to time fresh air needs to be collected at the surface because the bubble constantly looses nitrogen to the water, which cannot be recovered, so it keeps shrinking. The beetle does not need the nitrogen per se, but it needs to keep up the volume of the bubble to allow for the exchange of O2 and CO2 with the water. So occasionally, it comes to the surface for refills.

Thermonectus marmoratus, Sunburst Beetle
 Here is another beauty, the Sunburst Beetle. It's larger than a penny and catches the sunlight very nicely when it swims in flat water, propelled by strokes of its modified hindlegs.  


Agabus disintegratus, adult and pupa
Most Water beetles like Hydrophilidae and Dytiscidae lay their eggs under water, their larvae are aquatic, but to pupate, they have to come on land. I collected pupae under drift wood at Watson Lake in Prescott and let them hatch.

Large whirligig beetle, Dineutus sublineatus
Gyrinidae are primarily surface swimmers. They often form large aggregations and when disturbed swim in erratic circles (name!) . they have horizontally divided eyes and corresponding brain areas are devoted to seeing above and below the water surface respectively.  

Many true bugs lead aquatic lives, and all states of their life-cycle are water-bound, even though the adults of most species are good fliers. All I can think of a predatory and administer venom and digestive juices through their pointed 'beaks', some have raptorial arms, most have legs that are adapted to swimming and diving.

Graptocorixa (Water Boatman) Nymph
Water boatmen were in the news some time ago. A species in Great Britain was found to be the loudest animal on the planet, relative to its body size. It can create mating calls as loud as 99.2 decibels. The male water boatman produces this noise by rubbing his penis (or “genitalia appendage”) against the ridged surface of his abdomen.


Gerridae, Water Striders
Water Striders, Gerridae skate, using the surface tension of the water as their only support. They are predators and use their tactile sense to locate drowning, struggling insects that cause characteristic wave patterns. Getting close to the source, they switch to chemical prey recognition. A long time study subject of sensory and electro physiologists.

Water Scorpion Ranatra quadridentata, Madera Canyon, Sta Cruz Co, AZ
 This photo, borrowed from Historic Rivers Chapter, shows the bug breathing through a snorkel  at its hind-end. So thisis NOT  a stinger! Instead the bug catches prey with its raptorial arms and injects venom and digestive juices through its 'beak'

Larvae of Archilestes grandis (Great Spreadwing), Libellula sp. (probable Flame Skimmer), and Paltothemis lineatipes (Red Rock Skimmer) photo Bob Barber
 While beetles and true bugs are good fliers and can easily find new ponds and meet mates during their nightly excursions they spend most of their adult live ponds and streams.
Other insects that spread more delicate wings once they have outgrown their aquatic larval phase, do not return to the water as adults, except to deposit their eggs.
This great photo of Odonata (Dragonflies and Damselflies) was taken in New Mexico, but all three species can be found in Arizona as well.

Camelobaetidius larva, Sycamore Canyon, Santa Cruz County, Arizona, USA,
March, 13 2012
 Mayflies (Ephemeroptera) spend the longer part of their lives as aquatic larvae. Note the external gills along the abdomen. Mayflies are famous for the mass emergence of the short-lived adults. Unlike most insects, Mayflies go through a winged subadult state that is followed by one final molt to the imago.


Petrophila jaliscalis, Santa Cruz River, Between Wheeler Taft Library and Ina Bridge, 11-24-2014
Even some Lepidoptera have aquatic larvae:  During the day these little crambid moths can be found sleeping in the vegetation close to creeks and streams. They are night active and come to lights in late summer to fall..
Adult females enter the water to oviposit, carrying a plastron-like layer of air as a source of oxygen
The larvae are aquatic, living within a silken web in fast-flowing streams;
they scrape diatoms and other algae from rocks in streams.


Trichoptera or Caddisflies,, those hairy cousins of the scaly Lepidoptera, are obligatory aquatic breeders. Their larvae build tubes out of detritus and anker themselves on the bottom of slow moving creeks.

Corydalus texanus (Dobsonfly), Clear Creek, Yavapai Co, AZ
This is a female Dobson Fly, about the size of a wooden cloth pin. The males have amazingly long mandibles. Order Megaloptera: The female lays thousands of eggs in a single mass, placing them on vegetation overhanging water. Megaloptera undergo the most rudimentary form of complete metamorphosis among the insects. There are fewer differences between the larval and adult forms of Megaloptera than in any other order of holometabolous insects,  The aquatic larvae are carnivorous, possessing strong jaws that they use to capture other aquatic insects. They have large heads and elongated bodies. The abdomen bears a number of fine tactile filaments, which, in some species, may include gills. The final segment of the abdomen bears either a pair of prolegs, or a single, tail-like appendage. The larvae grow slowly, taking several years to reach the last larval stage. When they reach maturity, the larvae crawl out onto land to pupate in damp soil or under logs. The pupa is fully motile, with large mandibles that it can use to defend itself against predators. The short-lived adults emerge from the pupa to mate and oviposit - many species never feed as adults, living only a few days or hours.

These are just a few examples of the rich diversity that can be found even in Arizona's creeks and ponds. More than any other habitat, these ecosystems are delicate and threatened by pollution, grazing, mining and continuous droughts. 

Wednesday, February 11, 2015

A new True Bug species for our back yard


Leptoglossus brevirostris
 Well, not really new. Leptoglossus brevirostris was described by Barber in 1918. But new to me, and there was only one BugGuide entry so far, and that one was from Texas.


Yesterday I walked around with camera and Frodo to shoot some backyard birds (I finally want to put together a complete photo documentation for our backyard). I found that the desert mistletoe Phoradendron californicum - Mesquite Mistletoe is still blooming, attracting bees, flies and butterflies, but it also already offers enough berries for a number of birds to hang around.
There was also a true bug, a Leptoglossus sp. As 'true bugs' is this weeks theme for our Facebook group 'SW US Arthropods' I spent time photographing it from different angles, took dorsal shots and feeding portraits .... and then let it fly off into the clear blue Arizona sky. I thought I knew the species.

Notice the relatively short rostrum (not the thin filament, the thick kneed beak that just touches the berry)
 At home, enlarging the photos, I realized that I did NOT know the species. I should have collected it.
Recorde from AZ are Leptoglossus brevirostris Barber, 1918
Leptoglossus clypealis Heidemann, 1910

Leptoglossus occidentalis Heidemann, 1910
Leptoglossus oppositus (Say, 1832)
Leptoglossus zonatus (Dallas, 1852)

It did not have even a trace of the two yellow pronotal dots that characterize L. zonatus and that it did not look like L.clypealis, L. oppositus, or L. ocidentalis. There was a close likeness in a photo on bugguide from Texas, but the poster had also identified hers by excluding other possibles. L. brevirostris?

So I e-mailed a photo to coreid expert Harry Brailovsky in Mexico City and also posted it on my personal Facebook page.


This morning I had a Facebook message from Laurence Livermore from the Natural History Museum in London with a specimen photo of L. brevirostris from their collection and an email from Harry - 
Dear Margaret
Good morning from Mexico City.
Close or Leptoglossus brevirostris Barber.  Check if the rostrum is short not extending beyond posterior border of metasternum or anterior third of third abdominal segment (First).
  (my comment: this is visible in the feeding position in the image above)
Sincerely:
Harry Brailovsky
Instituto de Biologia,UNAM.
Departamento de Zoologia

So both confirmed that it is Leptoglossus brevirostris. My photo will now be added to the NHM's Coreoidea Species File profile. And of course it also goes into my own personal coreid collection on flickr.  Isn't the internet great?    
Another member of our Facebook group,  GY Zhang, found an interesting paper that deals with the insect fauna on mesquite mistletoe in Texas. It describes our Leptoglossus brevirostrum as host-restricted to this hemiparasitic plant. I knew that several coreids are very faithful to their cactus hosts, so it should not be too surprising that the mistletoe feeder also sticks to this one food source. I'm going to search  tomorrow - I should be able to collect a few specimens after all.