Friday, August 26, 2016

Sunflower Extravaganza

Few plants in arid climates can compare to sunflowers (Helianthus spp.) in their attractiveness to insects. Notice I said "plants" instead of "flowers." That is because while the sunflower blossoms are a beacon to bees, many other kinds of insects find secretions from the buds, stems, and leaves to be irresistible, too.

It is actually the sunflower's phyllaries (the bracts forming the involucre or the head or inflorescence of a composite plant), and the base of leaves, where the extrafloral nectaries are located. They produce a sweet substance different from floral nectar that insects crave. The main function of extrafloral nectaries (EFNs) is strongly suspected to be a means of recruiting insects to defend the plant against herbivores. Indeed, ants are the primary visitors to sunflower ENFs, and they vigorously pursue and rout any and all competitors.

A fly, two kinds of spider wasps (Pompilidae), and an incoming sweat bee (male Lasioglossum sp. on right)

Ironically, ants are also "farmers" of aphids, scale insects, and treehoppers that produce their own sweet product called "honeydew." Ants tenderly stroke these other insects until a drop of liquid waste appears at the rear end of their aphid or 'hopper "cow," and the ants eagerly lap it up. The aphids, scales, and treehoppers naturally manufacture honeydew as a by-product of their feeding activities....on the sunflower plant.

Treehoppers (Publilia sp.) tended by ants (Formica sp.)

So, while the ants guard the extrafloral nectaries, they also guard some of the insects doing the plant harm. Apparently no ecological relationship is perfect, but given the abundance of sunflowers, this one seems to work out ok anyway.

Parenthesis Lady Beetle and an ever-present ant

Even lady beetles utilize the ENFs as a source of hydration and vital nutrients during the summer months when there is a significant dip in aphid populations. I have seen several species on sunflower while looking for wasps.

Sunflower predator fest. Clockwise: Soft-winged flower beetle (Collops sp.), ambush bug (Phymata sp.), and assassin bug (Sinea sp.)

Other predatory insects recognize the lure of sunflower ENFs, too. Ambush bugs, Phymata spp., occur in abundance, and their success is measured by the many limp-bodied moths, butterflies, bees, and wasps dangling from their short beaks, or flopped across leaves below them.

Ambush bug with mud dauber wasp prey

It is the wasps, though, that are most astounding in their sheer diversity. I have found almost every conceivable family of wasps visiting sunflowers, and a high degree of diversity within each of those families in many instances.

Tiny chalcid wasp, Trigonura sp.

From the most minute of parasitic Chalcidoidea (a "superfamily" that contains several families of wasps) to large spider wasps and mud daubers, they are all there.

Female velvet ant, Dasymutilla bioculata

Even female velvet ants, wingless wasps which one usually sees scurrying across the ground, will scale tall sunflowers to reach those EFNs. Male velvet ants are even more frequent visitors, of course, with their ability to fly.

Large ichneumon wasp

Some individual plants are indeed tall, surpassing six feet in height. Those are mostly the Common Sunflower, Helianthus annuus. Locally, we also have Prairie Sunflower, Helianthus petiolaris, which is usually shorter, with purplish stems instead of yellowish green, and smaller, darker leaves.

The density of sunflowers in a given area can be mind-boggling as well. They thrive in "disturbed" habitats with sandy soil, which qualifies them to take over most of the urbanized Front Range here. Despite that, insects are noticeably attracted to only a few individual plants. So, once I find an attractive plant swarming with insect life, I stand by and watch as various wasp species come and go.

Female Svastra obliqua

Not a fan of wasps? No worries, a wide variety of bees visit the flowers, especially bumble bees, longhorned bees, leafcutter bees, and various cuckoo bees. Some bees, like Svastra obliqua, are even sunflower specialists. Composite flowers in general are bee magnets, but the very large surface of sunflowers gives bees plenty of bang for their buck in pollen and nectar. Sunflowers also bloom continuously for many weeks, even months, like a seemingly endless fireworks display.

Blue-black spider wasp, Anoplius sp.

One could literally write a book about all the insect visitors to sunflowers. Hm-m-m, that gives me an idea.....Meanwhile, enjoy the spectacle yourself next time you are in sunflower country.

Solitary wasp, Saygorytes sp.

Sources: Hodek, Ivo, Helmut F. van Emden, and A. Honek. 2012. Ecology and Behaviour of the Ladybird Beetles. UK: John Wiley & Sons. 561 pp.
Keeler, Kathleen H. 1979. "Species With Extrafloral Nectaries in a Temperate Flora (Nebraska)," Prairie Naturalist 11(1): 33-38.
Mizell, Russell F. 2015. "Many Plants Have Extrafloral Nectaries Helpful to Beneficials," EDIS, Institute of Food and Agricultural Scienes (IFAS), and University of Florida Extension, Publication #ENY-709.
The Great Sunflower Project.

Male Prairie Yellowjacket, plus spider wasp and ant

Saturday, August 20, 2016

Don't Sweat 'em

During the heat of summer, we all perspire. Some insects find that bodily function irresistible. Among them are sweat bees, various flies, and even butterflies. It is believed that the salts, minerals, and other compounds in our sweat are necessary for these insects, and difficult to find elsewhere. While you might assume that any insect landing on you intends to bite or sting, rest assured these insects are harmless.

Female sweat bee, Halictus rubicundus

Solitary and semi-social bees in the family Halictidae are collectively known as "sweat bees" because of their habit of lapping up human sweat with their short "tongues." They may tickle at most, but if you smack one absent-mindedly, it may indeed sting if it is a female bee. Male bees lack stingers.

Two different sweat bees, both Lasioglossum species

Sweat bees come in a variety of sizes and colors, from miniscule brassy Lasioglossum species to brilliant metallic Agapostemon species (and related genera). Members of the genus Halictus are medium-sized and brown or blackish with white bands across the abdomen. Nearly all species nest in the soil, each female excavating her own burrow.

Female sweat bee, Agapostemon sp.

Compounding the problem of recognizing the different insects that seek out your sweat is the fact that many flies in the family Syrphidae are wrongly called "sweat bees" in casual and regional language. Syrphid flies are more properly called "flower flies" here in the U.S. and Canada, and "hover flies" in Europe.

Tiny Toxomerus syrphid flies are often mistaken for sweat bees

Like bees, they can be important pollinators of flowers, but it is in their youth that they are most beneficial. The larvae of many flower flies prey on aphids, which are major crop and garden pests. Thus, the more syrphid flies, the better, even if they do want to drink your perspiration.

Unidentified syrphid fly on my arm, lapping sweat

Plenty of other flies, mostly blow flies (family Calliphoridae), and flesh flies (family Sarcophagidae), will land on us, too. Even some tachinid flies (Tachinidae) will wander around on bare hands and arms. They may not all be there for moisture or salts.

Tachinid fly using me as a lookout post

Some of these flies may be males that are simply using us as convenient perches from which to defend their territory. They will periodically fly off to chase away competing males, or pursue passing females.

Some butterflies are well-known for requiring certain minerals to complete their life cycle. Usually, male butterflies congregate around mud puddles, puddles of urine or piles of scat left by mammals, or even rotting carcasses, where they obtain nutrients that they will pass to females during mating.

Hackberry Emperor butterfly getting salts from animal dung instead of sweat

Males with a higher mineral content are more desirable to females, though how this is determined remains something of a mystery. She puts the transferred chemicals to good use in producing her eggs.

Occasionally, some butterflies will use us as substitutes for their usual mineral resources. I once had a Hackberry Emperor butterfly land on my toe while I was sunbathing in a park in Cincinnati. I had another land right on my sunglasses in a different location in Ohio, but he viewed me as a convenient perch from which to defend his territory.

Female Lasioglossum sweat bee with tongue extended, lapping sweat

Most research into the attractiveness of human sweat to insects has been directed at blood-feeding insects such as mosquitoes and other biting flies. Consequently, there is relatively little known, and much assumed, about the fascination non-biting "bugs" have with our skin pore excretions. One thing scientists can agree on? Don't sweat the sweat bees.

Tiny female Lasioglossum sweat bee on my fingernail

Source: Gibb, Timothy. 2015. "Do Not Confuse Hover Flies with Sweat Bees," Purdue Plant & Pest Diagnostic Laboratory, Purdue Extension, Purdue University.

Unidentified tachinid fly grooming itself on my arm

Tuesday, August 9, 2016

A Different Direction

Friends, I want to thank you for your continued patronage of this blog over the years. It has been, and continues to be, a privilege to serve you. At present, and for the foreseeable future, I find my life trending in different directions, and you will probably find fewer pieces of new content from now on. Please allow me to explain.

Most of the work I do to inform, educate, and fascinate is now done through social media, namely Facebook. I doubt I will ever indulge much in Twitter, or any of the other platforms, since I do not interact well with mobile devices (I am almost literally "all thumbs" on a tablet or smartphone). These platforms do, however, reflect something important that I must be cognizant of, and responsive to.

We are at a point where "instant gratification" is now possible through texting, internet messaging, and social media. The era of the blog may even be slowly coming to a close. No one wants to wait for a blog post when they are having a panic attack now over the spider crossing the kitchen floor. They can take a picture of it with their phone and send it over the airwaves to me or another expert immediately. This is the new 9-1-1, and 4-1-1, all wrapped up into one thing.

I honestly can't fault people for demanding information faster; and I would rather have it be me giving them a correct answer and advice than someone who does not know a brown recluse from a harmless wolf spider. Heck, I myself am "guilty" of using social media to get specimen identifications from authorities I trust. This is today's reality, and one must adapt or lose their impact and relevance.

Second, recent major expenses dictate that I must seek paying writing assignments and related work. I may even need to secure a traditional job outside the home, though I do not relish that prospect. Those who know me understand that I am not "greedy" or materialistic. Far from it. Still, even basic expenditures must be paid, and my income has increasingly stagnated. Doctor visits become more frequent as I age, with corresponding increases for medical bills. You get the idea.

Lastly, I have found increasing satisfaction from writing about topics completely unrelated to insects and spiders. So far, the outlet for this has been my other blog, Sense of Misplaced, but I am on the verge of seeking paying markets for personal essays and social commentary. I have loyal readers of that blog to thank for giving me the confidence and courage to believe that I can reach a far larger audience, and perhaps even influence cultural change and regulatory policies.

Our country, indeed the world, is in such a state of crisis that we need every voice to be heard. Every innovation, every idea, needs to gain an audience from those in places where those suggestions can be evaluated and implemented. I aim to be one of those voices for positive change, empathy, and leadership. I hope my audience here can transfer to my other blog, and on into mainstream media.

Meanwhile, I have enough posts in the Bug Eric archives that I feel it is still a sustainable resource. I continue to get positive, non-spam comments from new "recruits" delighted to find here the answer to that "mystery bug." I will still blog here periodically, at the very least to promote the work of others. Thank you again for your support.

Friday, July 22, 2016

National Moth Week, 2016: What's at Your Blacklight?

Today, Friday, July 22, kicks off the fourth annual National Moth Week, which runs through Sunday, July 31. I highly recommend participating, ideally in the formal sense of registering an "event" at their website. It can be public or private, as elaborate or as simple as you want to make it. Simply turning on your porch light this week and recording in images what comes flying in will add to our collective scientific knowledge while delighting you and your family.

A "prominent moth," Gluphisia sp.

Tonight I will be at the Fountain Creek Nature Center in Security/Widefield, Colorado, where the Mile High Bug Club and the nature center staff will be hosting an after dark celebration of moths. We are fortunate to have several members who have invested in UV tubes, mercury vapor lights, and other set-ups designed to draw nocturnal Lepidoptera and other insects. There should be at least two or three stations in different habitats.

Our simple light set-up

Meanwhile, my wife and I have a very low-tech apparatus consisting of a sheet, an 18-inch, 15 watt "party-style" blacklight, and a 4.5 watt, 120 volt 45 LED "work light." Most nights, weather permitting, we erect this in the backyard, all 12 x 10 square feet of it, fenced in as we are in a relatively urban Colorado Springs neighborhood. We should be attracting next to nothing except sideways glances from the neighbors. I have created a Flickr album, "Backyard Blacklighting, June, 2016," and will make subsequent albums for July, August, and September, too, documenting in images the diversity of insect life we see.

Ponderosa Pine Seedworm Moth

Blacklights produce light at the ultraviolet end of the spectrum, including wavelengths invisible to the human eye but easily detected by the insect eye. It is not recommended that one look directly at a blacklight, as UV rays are known to damage your eyes. Wearing white to a moth night event is also a bad idea as you will become a moving reflector and moths and other insects will alight upon you. You do not want a moth or beetle in your ear, so you will have to decide whether the risk is great enough to use earplugs.

American Bird's Wing Moth

Different moth aficionados will give you different advice, about everything from how to power your rig to what weather conditions are best. One standard is that the lunar cycle is important. The "new moon" (NO moon) is supposedly best, while the full moon is worst. Well, in June, one of our best nights was one day before a full moon. Go figure.

Sooty Chalcoela, Chalcoela iphitalis

Do what you are comfortable with, just look carefully before you give up, thinking that your lights did not attract anything worth your time. Many of our largest, most spectacular moth species are on the decline. Some are not drawn to lights anyway, or lurk on the fringes of the illuminated area. The greatest diversity, and often beauty, is in the "micros," those moths that are maybe ten millimeters or less in length. They can hide in folds in your sheet, or simply be so inconspicuous as to be overlooked.

Leafroller moth, family Tortricidae

We know very little about the overwhelming majority of moths, especially about where, geographically, they live. This is why taking pictures and sharing them is vital. You could easily document a "county record," verifying the first known occurrence of a species in your county. A "state record" is not out of the question, either, and that is a frequent outcome during moth week events.

Net-spinning Caddisfly, family Hydropsychidae

Your lights will draw other kinds of insects as well, some easily mistaken for moths. Chief among those are caddisflies, order Trichoptera. All are aquatic as larvae, but though you may be miles from water, you may still get the adult insects at your lights.

Brown lacewing

Brown lacewings, dustywings, and other members of the order Neuroptera can also look like moths at first glance. Their larvae eat aphids and other pests, so they are good neighbors, too.

Yucca moth, principal pollinator of yucca flowers

Remember not all moths are pests, by any stretch, and that they serve important purposes in pollination of flowers, and as food for birds, bats, reptiles, and other animals, including other insects.

Plume moth, family Pterophoridae

Have a very happy National Moth Week. You will not be disappointed if you choose to hold an event or join an existing, public one. There are many people willing to help you learn, in person, or online.

A "grass veneer" moth, family Crambidae