Currently viewing the category: "Blister Beetles"
What's That Bug? does not endorse extermination

Subject:  Big black bug!
Geographic location of the bug:  Northeast Pennsylvania
Date: 04/11/2019
Time: 08:45 AM EDT
Your letter to the bugman:  Hello! I found this while doing yard cleanup in one of my flower beds, under mostly dried grasses, and some damp leaves. It is about an inch to an inch & a half long & Was relocated to a far corner of the yard. Any idea what this is?
How you want your letter signed:  Knitwit in the poconos

Oil Beetle

Dear Knitwit in the poconos,
This is a Blister Beetle in the genus
Meloe, commonly called an Oil Beetle.  Blister Beetles should be handled with caution as some species are capable of secreting a compound known as cantharadin that can cause blistering in sensitive individuals.

Wow! Thank you for the quick reply and the great info!
~pj~

What's That Bug? does not endorse extermination

Subject:  What is this thing!?
Geographic location of the bug:  29 Palms, CA
Date: 04/08/2019
Time: 10:03 PM EDT
Your letter to the bugman:  Saw several of these critters crossing the dirt path as I was walking my dog. Took a couple shots and had on on the tip of my walking stick, hunched up with it’s butt angled down like it was stinging, and the front legs up looking poised for combat. Couldn’t get a shot of it like that since i was holding the stick and dog and camera and didn’t want to let the dog go in case they were stinging bugs…I at first thought they were velvet ants but nope…can’t find anything that looks like it online. they were about 1.5 to 2 inches in length…when i stopped to take pictures they all altered their path and came at me…what are they??
How you want your letter signed:  thanks, John Roush

Master Blister Beetle

Dear Josh,
This is a Master Blister Beetle, and though it does not sting, it does possess aposomatic or warning colors along with many Blister Beetles in the family Meloidae.  According to BugGuide:  “Pressing, rubbing, or squashing blister beetles may cause them to exude hemolymph which contains the blistering compound cantharidin. Ingestion of blister beetles can be fatal. Eating blister beetles with hay may kill livestock. Cantharidin is commercially known as Spanish Fly.”  We get several images of Master Blister Beetles from southern California and Arizona each April.  Just last week Daniel went to Joshua Tree National Park and he hoped to encounter some Blister Beetles, but alas, he returned without a single sighting.

Master Blister Beetle

What's That Bug? does not endorse extermination

Subject:  Blister Beetle?
Geographic location of the bug:  Potholes State Park, Grant County, WA
Date: 09/06/2018
Time: 09:21 PM EDT
Your letter to the bugman:  Spotted several unusual beetles on vegetation in the process of conducting a cultural resource technical visit.  While not an entymologist, some google research suggests that the beetles are Lytta magister (also known as the desert blister beetle or master blister beetle). If so, they seem a little out of their defined range and season; as they are reportedly out in the spring. I see that someone in WA came across one in 2011 http://myhorseforum.com/threads/blister-beetles.152491/page-2
Invasive species? Climate change?
How you want your letter signed:  Mr.? not sure what is meant by this question

Lytta vulnerata mating

Dear Mr,
We would have also concluded that these appear to be Master Blister Beetles, but additional research on BugGuide led to images of the closely related
Lytta vulnerata which is reported from Washington.  We cannot distinguish any appreciable differences in their appearance, so we are basing the identification solely on the reported range of the species.  That research also led us to a sighting on our own site that should also be corrected.

What's That Bug? does not endorse extermination

Subject:  Black and yellow bug
Geographic location of the bug:  NE Oklahoma
Date: 08/31/2018
Time: 08:09 AM EDT
Your letter to the bugman:  Hey bugman-
Tgaese are invading myhome. They are everywhere – walls, ceilings counter tops and even floor.  It hasn’t bitten or stung any one. . . Yet.
How you want your letter signed:  Cyndiluwho

Striped Blister Beetle

Dear Cyndiluwho,
This is a Striped Blister Beetle,
Epicauta vittata, and according to BugGuide: “Feeds on variety of plants, especially Solanaceae (e.g., potatoes, tomatoes), also soybeans, other crops. Pigweed, Amaranthus species, not a crop plant, is also fed upon extensively.” This is an outdoor species that occasionally enters homes accidentally, so we don’t know why you are finding so many indoors.  According to Featured Creatures:  “The adults are most active during the morning and late afternoon, seeking shelter from the sun at mid-day. In particularly hot, arid climates they remain inactive during the day, confining their activity to the evening hours.”  That site also notes:  “Striped blister beetle is one of the most damaging of the blister beetles to vegetable crops in areas where it occurs. This is due to its feeding preferences, which include several common crops and greater preference for foliage than some other species; its propensity to feed on fruits of solanaceous plants; its relatively large size and voracious appetite; its strong tendency to aggregate into large mating and feeding swarms; and its high degree of dispersiveness, which can result in sudden appearance of large swarms of beetles. … The damage caused by Epicauta spp. blister beetles is offset, at least during periods of relatively low beetle density, by the predatory behavior of blister beetle larvae. Epicauta spp. larvae feed on the eggs of grasshoppers, including many crop-damaging Melanoplus spp. During periods of grasshopper abundance the number of blister beetles tends to increase substantially.”  Blister Beetles should be handled with caution since some species are capable of secreting a compound, cantharidin, that is known to cause blistering in sensitive individuals.  We have selected your submission as our Bug of the Month for September 2018.

Striped Blister Beetle

What's That Bug? does not endorse extermination

Subject:  Large bluish beauty
Geographic location of the bug:  Outside Sackville, New Brunswick, Canada.
Date: 08/27/2018
Time: 11:38 AM EDT
Your letter to the bugman:  Walking near my parents’ trailer, I nearly stepped on this rather beautiful creature and couldn’t help but wonder what it is. It was generally inclined to stay still, but once I put it down, after lifting it for closer inspection, it was happy to race over very course gravel in order to get back to the tall grass.
How you want your letter signed:  Parker

Oil Beetle

Dear Parker,
This is a Blister Beetle in the genus
Meloe, commonly called an Oil Beetle because the iridescent surface of the beetle looks like oil on water.  Blister Beetles should be handled with caution, as many species are able to exude a compound called cantharidin that is known to cause blistering upon contact, especially in sensitive individuals.  The “crook” in the antennae indicates this is a male Oil Beetle.

Oil Beetle

Oh, my, thank you for the caution! It’s easy for me to forget about bugs (other than mosquitoes) presenting danger while vacationing up here. (Especially after an event a month or two ago where I helped a parent mud dauber rescue its young from a nest it had built on an RV. Didn’t want to bring the larvae to an inappropriate habitat.) I’ll be sure to observe from an appropriate distance from this point on.
Thank you again for your knowledge! It not only satisfied my curiosity, but also sparked some good discussions with my family.
Follow-up Questions:  I was wondering if I could get you to impart yet more knowledge; as I was cutting the grass, a saw some more of the oil beetles and developed a two general follow-up questions about the oil beetles. (Unfortunately I’d left my phone inside, so no pictures.)
First, on the pragmatic side, I believe there were several of the beetles this time, some with crooked antennae and some less so – I figure, then, that those are males and females. Do these beetles have any nesting or mating behaviors worth noting? They seemed to be congregating under my parents’ “laundry shed” (for lack of a better term – it’s a reused ocean container set on concrete blocks.) I ask because, while I assume the beetles are not aggressive towards humans from the nature of their defenses and my (very limited) observation, if they are going to be making a home there I want to make sure my dad doesn’t get blistered while doing maintenance.
My second question is out of curiosity more than anything else; I wonder how much is known about the oil beetle’s role in its ecosystem. We hadn’t seen any on previous visits up here, but now we’ve had several (my dad had seen one before me but mistook it for a large ant.) Might their presence have increased due to the land being slowly developed (i.e. addition of gravel and an ocean container and/or shorter grass)? I also got curious when I saw one beetle cross inches in front of a spider that seemed to be on a web. Admittedly, it was not a particularly strong-looking spider. I suppose I could have just mistaken a harvestman, really. Nonetheless, with their toxins, does much of anything eat them? Or do the oil beetles eat any kind of pest?
While I do get very curious about these things, I understand that you are busy and probably want to prioritize others’ questions. Thank you for all you do! It’s a great service to the world.
Hi again Parker,
Blister Beetles as a family tend to have complex life cycles.  Of the genus
Meloe, the Oil Beetles, BugGuide states:  “Larvae feed on eggs and other food in bees’ nests” and “In some species, triungulins [see definition below] aggregate and use chemical signals to attract male bees to which they attach themselves. This allows transport (and transfer) to a female bee who carries them back to her nest (Saul-Gershenz & Millar 2006).  First-instar larvae climb to the top of a plant as a group, clump together in the shape of a female solitary ground bee, exude a scent imitating the female bee pheromone. When a male bee comes and tries to mate with the clump of larvae, some of these clamp onto his hairs and eventually get to female bees when he mates for real. Impregnated female bees fly off and build nests in burrows; triungulins move to the new nests and feed on honey and pollen stocked by the bee for her own young. –Jim McClarin’s comment.”  Of the family, BugGuide notes:  “Life cycle is hypermetamorphic. Larvae are parasitoids. Eggs are laid in batches in soil near nests of hosts, sometimes in nest of bee host, or on stems, foliage, or flowers. Larvae undergo hypermetamorphosis–first instar larvae (usually called triungulins) are active, have well-developed legs and antennae. These typically search for hosts. Later instars tend to have reduced legs and be less active, having found hosts. There is a coarctate (pseudopupal) stage, which is usually how the larvae overwinter. Life cycle may be as short as 30 days, or as long as three years. It is typically one year, corresponding to that of host.

Triungulins of some meloids, e.g. in Meloe, aggregate and attract male bees with chemical signals (Saul-Gershenz & Millar 2006).”
Absolutely fascinating! Nature really is amazing. Thank you again so much!
What's That Bug? does not endorse extermination

Subject:  Small black beetles  with jewel colors of blue and violet
Geographic location of the bug:  Little Belt mountains Montana
Date: 08/20/2018
Time: 11:48 AM EDT
Your letter to the bugman:  I have seen these in the months of June and July on blooming mountain lupines in the Little Belt and the Castle Mountains. I would like to know what kind of beetle these are?
How you want your letter signed:  David C Powers

Blister Beetle

Dear David,
The image of a solitary beetle on a blossom is definitely a Blister Beetle in the family Meloidae, but we are uncertain of the species.  The other image showing an aggregation of Beetles appears to be a different species.  Can you clarify any information on these two images, especially the group of beetles.  Were they found aggregating as the image depicts?  Here is a BugGuide image of 
Linsleya sphaericollis that resembles the Blister Beetle in your image of a solitary individual, but again, we cannot verify the species.

Aggregation of Beetles

What's That Bug? does not endorse extermination