Category Archives: Beetles

Blister Beetles

Meloe strigulosus
Ventral view
San Juan Island, WA 11/2/2019

I posted back in April about an encounter with Blister Beetles not far from my house. You can read about that here ~ (https://cynthiabrast.wordpress.com/2019/04/16/a-blistery-spring-day/ ). Over the weekend of November 2-3, I came across quite a few more of these in the exact same spot as in April. This time I didn’t see any live beetles, but there were at least 25-30 dead in the road.

Meloe strigulosus
San Juan Island, WA
11/2/2019

Ever the opportunist, I scraped up as many that weren’t quite so smushed into a container and brought them home. Out of the 5 I collected, 2 were male, 2 were female, and one missed antennae altogether. Given the number of beetles in the road in this one spot, I believe this was a mating aggregation.

Meloe strigulosus (male)
San Juan Island, WA
11/2/2019

So, I’ve been reading about them and communicating with a two experts on blister beetles. If you don’t know what these are, they are significant because of a defensive chemical in them called Cantharidin. Cantharidin is quite toxic and it’s a blistering agent. This is where they got the name Blister Beetles in the first place.

antennal segmentation of male Meloe strigulosus
San Juan Island, WA
11/2/2019

Since my first sighting of these beetles back in April, I’ve learned quite a bit about them. The ones here (Meloe strigulosus) are black, flightless, tanker-like beetles, carrying around a cargo of toxic brew. They are sometimes a hazard to livestock (actually almost all mammals) that might eat them because the Cantharidin is toxic. Horses, goats, cows, and sheep that eat alfalfa hay can get really sick with colic if there are even parts of dead beetles in the hay.

While we don’t really know exactly how Cantharidin is produced in the beetle, we do know these two things: 1) it’s produced in the male and transferred to the female during mating. 2) the female transfers Cantharidin as a protective coating for her eggs during oviposition. It’s believed that the first instar larvae (called triungulin) are equipped with a supply of Cantharidin as well.

After hatching, the triungulin crawl up onto flowers to hang out and wait to attach to the hairs of a visiting bee, riding back to its nesting site. The later developmental stages of larvae are protected underground or in holes in wood where native bees are developing. They consume the developing bee eggs, larvae and nest provisions (pollen and nectar).

Is there anything good about blister beetles? Well, strangely, the populations of some species of blister beetles are timed to coincide with grasshopper abundance. Adult blister beetles feed on grasshopper eggs. That’s good, right?

What else? Humans have used Cantharidin for years to remove warts and to remove tattoos as well. For ages, it has been used as a sexual stimulant. Even birds called Great Bustards have picked up on this! Read more here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521026/

Blister beetles seem to be beneficial to some other species of beetles too. There is one beetle that actually has been found to chew on the blister beetle as a means of obtaining Cantharidin for its own protection. Other animals like toads, frogs, and armadillos are known to eat these beetles or use them in some way to confer protection. There is even a nuthatch that uses the beetle to “sweep” the wood where it wants to build a nest to protect it from parasites.

Back to my weekend sighting and collection of a few of these specimens. I had two that were intact enough to pin for my collection. I wore nitrile gloves to make sure I didn’t come into contact with any blistering agent. It’s a good thing I did. Some fluid made contact with one of the fingers of my gloved hand and actually started eating through it. That’s pretty caustic!

If you’re interested in more information about them, I’m happy to email some of my collected literature. There are also links you can check out in my previous post from April.

Thanks for reading!

Monochamus scutellatus, the Whitespotted Sawyer Beetle

Monochamus scutellatus
Canoe Island
August 12, 2019
Photo by Chase Stoddard
Monochamus scutellatus
Canoe Island, August 12, 2019

I received this photo yesterday of a very cool Cerambycid (Long-horned) beetle from Chase S. on Canoe Island, WA. This is a Whitespotted Sawyer beetle (Monochamus scutellatus). These beetles are found in forested areas across the continent. The first time I saw one on San Juan Island, I almost mistook it for a giant black spider. Its long antennae give it the appearance of having eight legs, like an arachnid.

The larvae (known as sawyers) of Monochamus beetles develop in the wood of fire-scorched, diseased or injured, dying pine, Douglas fir, true firs, and spruce trees. The adult beetles lay eggs in slits in tree bark. Larvae (grubs) develop through several instars before pupating. The younger larvae feed on wood beneath the bark and filling the void with long, fibrous borings, then move into the wood, forming holes that will become almost perfectly round as the tunnel grows deeper. The tunnels can eventually reach the heartwood of the tree.

Prior to pupation, the larvae will pack the deep gallery with grass, leaving a space at the end for the pupal cell or chamber. Adults will emerge by gnawing through the cell and a thin layer of wood and bark to the surface. Telltale signs of boring damage is the accumulation of debris along infested logs. As they can attack and damage recently felled trees, they are considered a pest in logging areas. According to Furniss and Caroline’s 1977 Department of Agriculture Forest Service Publication No. 1339, utilization of preventative methods that avoid leaving logs exposed during the beetles’ egg laying period ( July-September ) is the best approach.

Monochamus scutellatus White-spotted Sawyer
August 30, 2010
Photo by Cynthia Brast
San Juan Island, WA

References:

Furniss, R. L. (Robert Livingston)., Carolin, V. M. (Valentine M.)., United States. Forest Service. (1977). Western forest insects. [Washington]: Dept. of Agriculture, Forest Service : for sale by the Supt. of Docs., U.S. Govt. Print. Off..

Haggard, P. and Haggard, J. (2006). Insects of the Pacific Northwest. Timber Press Field Guide.

Peterson, M.A. (2018) Pacific Northwest Insects. Seattle Audubon Society.

Western Blood-red Lady Beetle

I found three different species of Lady Beetles in my garden this past weekend and wanted to share a bit about them with you. I’ll start with the Western Blood-red Lady Beetle or (Cycloneda polita), also sometimes called the “Polished Lady Bug.”

If you are someone who needs reading glasses (like me) to see things up close, you could easily be fooled into thinking the spot of red on the plant leaf is a drop of blood. Given how accident prone I am, when I first spotted this one, I figured I’d poked my finger again on one of the prickly berry vines that are coming up in my raised garden beds. Upon closer inspection, I was glad I had my camera phone handy.

Western Blood-red Lady Beetle (Cycloneda polita)
July 14, 2019
San Juan Island, WA

Ladybird or ladybug beetles are a large and very diverse group of beetles. They are classified in the insect order Coleoptera, family Coccinellidae. Most are known to be highly beneficial, feeding on garden pests like aphids. The Western Blood-red Lady Beetle is one of our native ladybird beetle species. Unfortunately, research is indicating we are losing our native ladybird beetle populations as they are outcompeted by imported non-native ladybird beetles released for biological control.

Western Blood Red Ladybird Beetle (Cycloneda polita) on Daisy
July 19, 2019
San Juan Island, WA
Western Blood red Ladybird Beetle (Cycloneda polita)
July 19, 2019
San Juan Island, WA

Further information can be found by following the links below.

*Distribution of Cycloneda politahttps://www.discoverlife.org/mp/20p?res=720&see=I_JEL1585;&start=http://www.discoverlife.org/users/l/Losey,_John/JEL.html

*Lost Ladybug project http://www.lostladybug.org/files/LLP%204HSet3-6.pdf

*Bugguide https://bugguide.net/node/view/15623

Xestoleptura crassipes

Xestoleptura crassipes
San Juan Island, WA
July 16, 2019

Xestoleptura crassipes is a species of flower longhorn beetle. Taxonomically it is placed in order Coleoptera, family Cerambycidae. The species name “crassipes” means “thick-legged.” Adults are attracted to flowers (June-September) and larvae are wood borers, found in forested areas and associated with firs and oaks. Adult body length approximately 10-17mm.

I photographed this specimen on July 16, 2019. It was the only one on the daisy plant by my front door. On the morning of July 18, there remained the single beetle (or I believed it to be the same one). That evening, I observed a 2nd beetle feeding on an adjacent flower. This morning (July 19th, 2019), they were both gone. Perhaps this was a successful meetup for finding a mate. 🌼

Xestoleptura crassipes feeding on daisy pollen

A Blistery Spring Day

I walked down the road last Tuesday (April 9, 2019) with my husband.  It was late afternoon and although it rained a bit earlier that morning, the sun was peeking out.   The wind wasn’t blowing, but it was soon to be a Blistery Spring day!

If you know any entomologists, you’ll understand rule #1 about going on ANY walk is to take a collection jar and a camera.  Last week, I failed to do this and missed an opportunity to identify and document this very cool bumble bee mimicking fly (genus Laphria ~ a bee-like robber fly).  This time I made certain to take my phone.  Sure enough, at the bottom of the hill, I see a black beetle crawling about on the chip-sealed road.  Fortunately, I refrained from my very bad habit of grabbing things with my bare hands. This is one beetle you do NOT want to pick up!  It was a BLISTER BEETLE.

Lucky me! I came home with some great photos and some video footage instead of a dermatological eruption that would have landed me in the doctor’s office.  I left the beetle in the road to continue whatever it was doing.

Back at home, I used my reference books to compare the photos and video I took of the beetle and narrowed down an ID to the genus Meloe.  I would need more help figure out the species.  I sent some photos off to Merrill Peterson at WSU with the suggestion that it might be a male Meloe niger.  Merrill wrote back that he thought it was M. strigulosus, but hard to confirm with only a photo.  He agreed it was indeed a male.

Meloe niger Black Meloe Blister Beetle

Meloe strigulosus (male)

You might ask how one goes about determining whether a particular beetle is male or female.  Often, as in this case, the male antennal segments are larger or varied in shape from the female.  This beetle’s antennae had a distinctive kinked platform on their fifth segment.  I would learn later that this kinked part enables them to grasp the antennae of the female during mating.

Meloe strigulosus (male)

Meloe strigulosus photo by Cynthia Brast April 9, 2019 Three Corner Lake Road San Juan Island, WA

Antennae

kink in antennal segment of M. strigulosus (male)

Merrill also sent me a link to what I will refer to as the Blister Beetle bible.  Published in 1970, this research was compiled by the legendary systematics entomologist, John D. Pinto, currently professor emeritus at U.C. Riverside with Richard B. Selander.  Hopeful, I sent off my photos in an email to Dr. Pinto and felt really privileged when I got an almost immediate response.

According to Dr. Pinto, the specimen I photographed was indeed a male Meloe strigulosus.  If you’re interested, you can read “The bionomics of blister beetles of the genus Meloe and a classification of the New World species”by linking here https://archive.org/details/bionomicsofblist42pint  Aside from the wealth of information published in this book, I love the artistic rendering of the female beetle on the cover.

Screen Shot 2019-04-15 at 11.53.12 AM.png

Illustration from Pinto and Selander’s “The bionomics of blister beetles of the genus Meloe and a classification of the New World species.” 

According to Dr. Pinto, there are 22 species of Meloidae in North America.  They are named Blister Beetles because they release a toxic terpenoid blistering agent called cantharadin when they are threatened or handled.  Sometimes people call them “Oil Beetles” because it’s oily. You can find the chemical profile of cantharadin here ~ https://pubchem.ncbi.nlm.nih.gov/compound/cantharidin#section=Drug-Indication

Curiously, this toxic secretion has been utilized to treat various medical conditions.  Among these was the topical application of the “oil” to treat rheumatism or to remove warts and lesions of Molluscum contagiosum, a contagious, viral infection of the skin (https://www.mayoclinic.org/diseases-conditions/molluscum-contagiosum/symptoms-causes/syc-20375226).  Cantharidin is also famously known for its use as an aphrodisiac (Spanish Fly).   This substance was historically used as a treatment for hydrophobia (rabies).  Male beetles were preserved in honey, mixed with other equally toxic ingredients then administered in an attempt to cure the patient. Maybe dying from cantharadin poisoning was less traumatic than dying of rabies.

Blister beetles are economically important because they contaminate alfalfa hay and they are highly toxic to livestock, especially horses.  There are instances where a horse has died from ingesting just ONE beetle. According to this Colorado State Extension publication (https://extension.colostate.edu/topic-areas/insects/blister-beetles-in-forage-crops-5-524/), just the release of cantharadin oil from the beetle can contaminate the hay.  Although reports of cantharadin poisoning in livestock are rare in the West, here’s one case where someone’s goat became very sick from ingesting hay contaminated with cantharidin ~ https://www.vetmed.ucdavis.edu/news/uc-davis-veterinarians-discover-blister-beetle-toxicity-goat

Another interesting fact about these beetles is that the larvae are phoretic parasites of solitary bees and grasshopper egg pods.  The first instar larvae, called triungulins” crawl onto flowers to await a visiting bee, then hitch a ride back to the nest where they will consume the pollen, nectar, and even the bee larvae.  Check out this link from National Geographic to view some extraordinary images of bees covered with blister beetle larvae ~ https://www.nationalgeographic.com/animals/2018/09/bees-blister-beetles-evolution-parasites-pheromones-news/

This was the first blister beetle I’ve seen on San Juan Island, but I do know of one other sighting by San Juan County Land Bank steward, Doug. M. from April of 2016.  I sent the photo of Doug’s beetle to Dr. Pinto as well and this was his reply, “Very likely M. niger – tho the photo is a little fuzzy for positive ID.”  Doug’s photo of the “likely” M. niger below.   

Meloe niger 2016-04-07 14.38.37

Meloe niger Mount Ben, San Juan Island, WA, April 2016                                                                     Photo by Doug. M. San Juan County Land Bank

If you’d like to read more about the particular species of blister beetle I found, I’m including the taxonomic key and geographic distribution data from Dr. Pinto’s book below.

                                               Meloe (Meloe) strigulosus Mannerheim


 Direct Key To The New World Subgenera of Meloe

Key to New World Subgenera of Meloe

Key to New World Subgenera of Meloe Pinto and Selander, 1970

Direct Key to the New World Subgenera page 104.

Direct Key to the New World Subgenera of Meloe page 104 Pinto and Selander, 1970

Key to Groups

Key to Groups p. 124

Key to Groups Bionomics of Blister Beetles Pinto and Selander, 1970

Direct Key to Groups page 157

Key to Groups Bionomics of Blister Beetles Pinto and Selander, 1970

 Geographic distribution

Geographic.distribution of M. strigulosus  p. 159

Geographic Distribution of Meloe strigulosus Pinto and Selander, 1970

Larval Key Meloe strigulosus

Larval.key.1

Larval key Meloe strigulosus Pinto and Selander, 1970

Larval.key.2

Larval key for M. strigulosus Pinto and Selander 1970

Antennal illustrations for male Meloe strigulosus, Figure 125 a. Dorsal view of segments V-VII, and b. Posterior view of segments V-VII

Male Antennae

Male antennae M. strigulosus Pinto and Selander, 1970

Antennal illustrations for female Meloe strigulosus, Figure 140

Female Antennae

Female Antennae M. strigulosus Pinto and Selander, 1970

References

Bittell, J. 2018.  Sex, Lies, and Grappling Hooks: How Parasitic Beetles Trick Bees. Animals Weird and Wild. National Geographic.  https://www.nationalgeographic.com/animals/2018/09/bees-blister-beetles-evolution-parasites-pheromones-news/

Hafernik, John and Saul-Gershenz, Leslie. 2000. Beetle larvae cooperate to mimic bees. Nature. 405. 35-6. 10.1038/35011129.

Kinney, K.K., F.B. Peairs and A.M. Swinker. 2010.  Blister Beetles in Forage Crops. Colorado State University Extension Publication 5.524. https://extension.colostate.edu/topic-areas/insects/blister-beetles-in-forage-crops-5-524/

Mayo Clinic. Mulluscum contagiosum. https://www.mayoclinic.org/diseases-conditions/molluscum-contagiosum/symptoms-causes/syc-20375226(accessed on Apr. 16, 2019)

National Center for Biotechnology Information. PubChem Database. Cantharidin, CID=5944, https://pubchem.ncbi.nlm.nih.gov/compound/5944 (accessed on Apr. 16, 2019)

Peterson, M. A. 2018. Pacific Northwest insectshttps://www.amazon.com/Pacific-Northwest-Insects-Merrill-Peterson/dp/0914516183

Pinto, J.D. and R.B. Selander. 1970. The bionomics of blister beetles of the genus Meloe and a classification of the New World species. Illinois Biological Monographs 42: 1-222.  https://archive.org/details/bionomicsofblist42pint

Piuser, J. 2017. UC Davis Veterinarians Discover Blister Beetle Toxicity in Goat. U.C. Davis Veterinary Medicine.  https://www.vetmed.ucdavis.edu/news/uc-davis-veterinarians-discover-blister-beetle-toxicity-goat

Quinn, M. Blister Beetles of Texas. Texas Beetle Resources. http://texasento.net/TXMeloidae.html#Meloe  (accessed on Apr. 16, 2019)

Scanning Electron Images of a Cerambycid Beetle

Yesterday I had the extreme good fortune to be able to use the scanning electron microscope (SEM) at University of Washington’s Friday Harbor Labs (San Juan Island).  We put a Cerambycid beetle under the SEM and “WOW,” the photos were phenomenal!  Here’s a few for you to see.  Below is a photo of the beetle’s compound eye.  Just think of all the information each of those facets receives and processes.

IMG_7528

Cerambycid beetle compound eye, imaged under scanning electron microscope at Friday Harbor Labs, San Juan Island, WA

Next, you see an image of the beetle head.  It shows the antennal insertion points, the compound eyes, frons, clypeus, labrum, mandibles, and bristly setae.

IMG_7526

SEM anterior, dorsal view of cerambycid head.

If you’re interested in learning more about the morphological features, here’s a pretty good diagram below for reference.

morph12

image from http://www.faculty.ucr.edu/~legneref/biotact/bc-51b.htm

The last image for you is of the beetle’s tarsi (the foot).  This is an important identification feature for many insects.  Imagine that!  When I was working on my masters degree from the University of Florida, I had an amazing taxonomy professor who was an expert on Coleoptera (the beetles).   He created identification keys for Florida beetles and you can take a look at them here:  http://www.entnemdept.ufl.edu/choate/beetles.pdf IMG_7525.JPGWell, I’m looking forward to using the SEM again and my next imaging will hopefully include the sponging mouthparts of a fly.   Stay tuned!

Suit of Armor

Ironclad beetle - Zopheridae

Ironclad beetle Phellopsis porcata

Yesterday’s “Word of the Day” on my new Facebook Page https://www.facebook.com/buggingyoufromSJI was “ Thanatosis.”  Thanatosis is a behavior otherwise known as “playing dead!” Here’s an insect I found on the roadside the other evening, doing exactly that. Only about 15mm long, it was amazing to even recognize it as something other than a piece of bark.

What is it? This beetle is in the family of Ironclad beetles known as the Zopheridae. It is a species called Phellopsis porcata, one of only two North American species in the genus Phellopsis. Little is known about this cryptic beetle, a bumpy, and bark-like “armored soldier.” It is camouflaged from view in what remains of our old-growth forests. This beetle does not fly, so as habitat disappears, so will the beetle. We may never know the entire scope of its role in our forest ecosystems unless these areas are protected.

What do we know about P. porcata? Researchers have documented the behavior of thanatois or playing dead to escape predation, and in the Pacific Northwest, this species feeds on fungi and is associated with western hemlock trees (Tsuga heterophylla).

 

Ironclad beetle - Zopheridae

Here’s a great online diagnostic tool that can help with identifying Ironclad beetles. This links to the page I used to help with the genus Phellopsis: http://coleopterasystematics.com/ironcladid/IroncladID-Phellopsis.html .   Look for these cool beetles when you take your next walk in the forest!

Read more

The Fainting Bug! Enoclerus sphegeus

IMG_0997I like beetles. There are interesting ones all over the place…and they do REALLY interesting things. Some can cry like babies. Some like to pat poo into nice little balls and roll them back to their home. Some hang around to take care of their offspring and even “play music” to call them to breakfast…or lunch…or dinner! Some do “bad” things like eat your plants …or your trees…or your house! Some wear really cool suits of shiny armor. They can look like miniature versions of dinosaurs or imaginary space aliens! Some have really cool names…like this one I found the other day…with many friends…hanging out on a dead fir tree. Its name? The FAINTING beetle! That’s exactly what it did when I walked up….fainted right over onto the ground! Stayed that way too…for about 30 seconds with its bright red (aposmatically colored) abdomen warning me it would taste VERY bad if I decided to eat it. No worries there little bug. I was only going to take your photo. Now the scientific name of this fella (or maybe it was a “she”) is Enoclerus sphegeus. It eats the bark beetles that eat fir and pine trees. Check out the photos and next time you see a beetle, take a moment to “admire and inquire” before you automatically stomp it! Not all bugs are bad.

Interested to know more.  Check out some of these references for further reading:

Boone, C., Six, D., and K. Raffa. 2008. The enemy of my enemy is still my enemy: competitors add to predator load of a tree-killing bark beetle. Agricultural and Forest Entomology, 10(4), 411-421.

http://onlinelibrary.wiley.com/doi/10.1111/j.1461-9563.2008.00402.x/full

Cowan, B., and W.P. Nagel. 1965. Predators of the Douglas Fir Beetle in Western Oregon.  Agricultural Experiment Station, Oregon State University, Corvallis, OR. Technical Bulletiin 86 http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/8806/?sequence=1

Rasmussen, L. 1976.  Keys to Common Parasites and Predators of the Mountain Pine Beetle. USDA Forest Service Intermountain Forest and Range Experiment Station. Ogden, UT. General Technical Report INT-29

Click to access 1976Rasmussen_Key%20to%20Common%20Parasites.pdf

Fainting Bug, Enoclerus sphegeus IMG_0990Enoclerus sphegeus, the Fainting Bug IMG_0992Enoclerus sphegeus, the Fainting Bug IMG_0994 IMG_0997 IMG_0999 IMG_1000 IMG_1001

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