In this article, I will describe the blister beetle life cycle in detail.
Blister beetles live a very unique and complex life cycle that is different from other insects.
Their larvae are predaceous from the get-go, hunting for grasshopper eggs in the soil. As they forage for food, they grow bigger and, after about four stages, turn into pseudo pupae.
The pupae then overwinter, lying in wait for the temperatures to rise so that they can finally come out as adults, feed, and mate.
These beetles can live a lifecycle that lasts just three months – but they are also capable of living beyond three years if the need arises!
If you would like to know more about their life cycle, I will share all the necessary details in this article.
What Are Blister Beetles?
Let us first give a brief background about these much-feared and reviled beetles.
Blister beetles consist of several species of the family Meloidae that feed on crops, flowers, and grasses.
They have grey or black hard-shell bodies with either orange or yellow stripes running down their backs.
They range from about 10-20 mm in length and contain an oil called cantharidin – a powerful chemical that is used as a defense mechanism against predators.
When ingested or touched by humans, this oil can cause serious skin blistering and inflammation.
Additionally, the larvae of these insects affect forage crops such as clovers and alfalfa. This makes them dangerous to livestock if not properly managed.
Life Cycle of Blister Beetles
Blister beetles have a strange and unique lifecycle. In fact, they can complete a whole lifecycle in just 30 days – but sometimes their life stages can keep running for beyond three years!
Adults Emerge To Mate
These bugs overwinter in the soil as pseudo pupae.
In June and July, adults emerge from these pupae once the temperature and moisture improve during spring.
As adults, the insect congregates on plant leaves and flowers and feeds on pollen.
After their feeding frenzy, the adults turn to mate and produce the next generation.
Blister Beetles most commonly have only one generation a year, especially in the Northern Plains.
However, in the south, they have been known to produce two generations.
Eggs Are Laid
Once they start mating, the activity happens quite often. Every now and then, the females start laying eggs.
It takes between two to three weeks after mating to lay eggs. They lay about six clutches each time, and every one of these may have upto hundred eggs.
Typically, the eggs are laid in small orifices in the soil (about 1 to 2 inches deep), somewhere where the young larvae will have enough food for their survival.
Sometimes, they might also be laid under stones or even on the plants which the adults were feeding on.
But plant food is not the only thing the females are looking for.
The abundance of blister beetles is influenced by grasshopper abundance since grasshopper eggs are one of the most important food sources for larvae.
The dependence is so high that in years with high grasshopper populations and the ones that follow, you can see an increase in blister beetle populations.
The Larvae Come Out
After about 10 to 16 days, the eggs start to hatch, and the little larvae come into the world.
They would spend four distinct stages gathering strength and becoming ready to emerge as beetles.
The first stage is perhaps the most energetic one.
The beetle larvae are called triangulin in this phase. Despite being new to the world and their surrounding, they are able to reach their food.
That’s because these larvae are blessed with tiny legs designed so that they can walk around in the soil.
The larvae immediately find and start eating grasshopper eggs to their heart’s content. This goes on for some time until they are full to the brim.
Grubs
Once they are done, these larvae transform into grub-like creatures, which is what they continue to look like till their fifth or sixth instar.
After the fifth or sixth stage, they start becoming lazier and lazier and stop moving about completely. Their outer shell also becomes very hard.
Once this happens, their muscles start to degenerate, and breathing falls to a very low level.
All of this is meant to make them capable of surviving for more than a year in this form. This is the pseud pupa stage that we started our story with.
Pupae
Before becoming a pupa, the larvae molt several times. Toward the end, they go back to the soil from which they emerged.
Their pupae stage looks very nearly like the adult beetle, except for the wings and legs, which are held very tightly to the body.
When they start out, the pupae are white, but with time the color darkens as they get ready.
The pupae are initially whitish in color and grow darker as they mature and lie in wait for the spring season to come.
And thus restarts the cycle of life once again in spring and fall.
What Do Blister Beetles Eat?
Blister beetles are a bit of a plant pest. The adults, as I mentioned earlier, feed on plants.
This could include anything from tomatoes to peppers, eggplants, beans, potatoes, and more. Basically, anything you might be growing in your garden.
They have a particular love of legumes, by the way.
If you think your flowering plants are safe from them – think again. These beetles can swarm your home garden and start sucking down your beautiful flowers.
But the most important thing they feed on is alfalfa.
Why is this important? Well, alfalfa hay is fed to horses, and the chemical that these beetles produce is toxic to horses.
Lastly, the larvae are big on grasshopper eggs, so they can be very helpful in a garden full of these pests.
But you wouldn’t want to bring blister beetles into your garden just to get rid of grasshoppers, now would you?
Do Blister Beetles Fly?
Yes, as I said earlier – these beetles can fly short distances.
They tend to travel in swarms when they are doing this, so it is important to watch out for them when they are flying.
However, their normal course of movement is just walking; they don’t fly a lot.
Neither do they need to – after all, their reflex bleeding is a protective method that keeps them safe from most predators.
Frequently Asked Questions
What metamorphosis are blister beetles?
Blister beetles are insects that undergo complete metamorphosis. This process involves four distinct stages: egg, larva, pupa, and adult.
Blister beetle larvae feed on other insects, such as grasshopper eggs or caterpillars; however, as adults, they feed on plants.
The adult stage of the blister beetle is the most recognizable: it has a yellowish or brownish body with a black head and thorax.
Their bodies have grooves along the abdomen which make them stand out from other species of beetles.
What stage do blister beetles cause damage?
Blister beetles cause damage at the adult stage when they feed on economic crops.
Generally, they feed on young pollen and nectar-rich plants such as vegetables and fruits.
They also often migrate in large numbers to their favorite sources of food, which results in mass crop damage.
When adults are disturbed or handled, they can emit an irritating chemical from their joints which can cause blisters on the skin.
Adult beetles also have chewing mouthparts that allow them to chew through the plant material to lay eggs in the soft tissue of plants and fruit.
Are blister beetles harmful?
Yes, blister beetles can be harmful. They are known to damage crops such as alfalfa and melons by consuming their leaves and flowers.
Additionally, some species of blister beetles have toxins in their hemolymph (blood-like fluid) that can cause skin blisters and irritation when humans come into contact with them.
In other cases, blister beetles can infest homes and cause health problems for people who live in these affected areas.
People should take the necessary precautions to ensure they stay away from blister beetles whenever possible.
What happens when a blister beetle bites?
Blister beetle bites are not particularly dangerous, but they can still cause biting sensations and skin irritations.
When someone is bitten by a blister beetle, the area will turn red and swell up.
The affected area may appear bumpy and feel hot to the touch.
If a blister beetle bite begins to itch or gets worse over time, it might be best to seek medical attention as the bite may become infected.
Home remedies such as baking soda paste or essential oils may also help reduce skin irritation and discomfort caused by blister beetles.
Wrap Up
From spending the early days of their lives foraging for grasshopper eggs to pupating, emerging as beetles, and wreaking havoc on crop plants, bister beetles lead an amazing life.
Their strange and unique lifecycle enables these insects to be quite hardy, surviving for more than three years as pseudo pupae under the soil.
I hope I was able to give you all the answers you needed about their life cycle, which parts of it are dangerous to humans, and more.
Thank you for reading.
Reader Emails
In those parts of the world that blister beetles live, it is not uncommon to find their larvae or even the pupa stage in the soil.
After all, these bugs don’t hide themselves too deep – just an inch or two beneath the ground.
Some of our readers have found a beetle or two and asked us all about what it was. Read these letters and watch the pictures as well.
Reader Emails
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Letter 1 – Iron Cross Blister Beetles Mating Frenzy
Please Identify
I live in Central Arizona. I traveled to Lake Roosevelt to put my boat in the lake and I found hundreds, if not thousands of these crawling, climbing and flying around the storage yard. It was horribly hot that day, roughly 105. these bugs seemed to stay in the sun. some of the bugs were eating leaves and the rest seemed interested in procreation only. The elevation was roughly 1300′ above sea level. The time of year was early May. The terrain was desert. Surrounding vegetation is short bushes and some mesquite trees, with little ground cover.
Thanks,
Jim Scott
Hi Jim,
Your Iron Cross Blister Beetle mating frenzy is a nice addition to our Bug Love pages. These Blister Beetles are one of two possible species in the genus Tegrodera. It is most likely Tegrodera latecincta.
Letter 2 – Mating Iron Cross Blister Beetles
iron cross blister beetles — mating on cactus
Hi:
Thanks for helping me identify my bug — your site is great. I thought you might enjoy the picture of two iron-cross blister beetles ( Tegrodera latecincta ) mating on a cactus — it all looks a bit precarious! The cactus is a local “hedgehog cactus” ( Echinocereus sp. ). My yard was invaded by these bugs over the past couple of days; I’ve lived here 6 years and never seen them before. Best,
Jake
NW Tucson, AZ
Mid May 2008
Hi Jake,
Your photo of Iron Cross Blister Beetles mating is quite stunning.
Letter 3 – Iron Cross Blister Beetles Mating
What is it?
I met with this and many others like it on my patio. Should I run?
Dave K
Hi Dave,
Put on the brakes. There is no need to run from the Iron Cross Blister Beetle, Tegrodera latecincta, as it will not attack you. It is, however, not perfectly harmless. Blister Beetles are capable of exuding an irritating chemical from their let joints that can cause blisters, hence the common name.
Letter 4 – Iron Cross Blister Beetles Mating Frenzy
Please IdentifyI live in Central Arizona. I traveled to Lake Roosevelt to put my boat in the lake and I found hundreds, if not thousands of these crawling, climbing and flying around the storage yard. It was horribly hot that day, roughly 105. these bugs seemed to stay in the sun. some of the bugs were eating leaves and the rest seemed interested in procreation only. The elevation was roughly 1300′ above sea level. The time of year was early May. The terrain was desert. Surrounding vegetation is short bushes and some mesquite trees, with little ground cover.
Thanks,
Jim Scott
Hi Jim,
Your Iron Cross Blister Beetle mating frenzy is a nice addition to our Bug Love pages. These Blister Beetles are one of two possible species in the genus Tegrodera. It is most likely Tegrodera latecincta.
Letter 5 – Blister Beetles Mating
Tiger Beetle in Sunol Regional Wilderness
We found these 2 tiger beetles yesterday (3/29/07) in the Sunol Regional Wilderness
park; that’s northern CA, East Bay, but I’m not sure which county. It’s definitely not the 6 spotted tiger beetle. I hope you can identify it. Or, after further searching your site, maybe it is: Cicindela_sexguttata, as I see that they can come without spots and they must be quite common. thank you,
Katherine Suri
back yard naturalist
Hi Katherine,
Tiger Beetles are carnivorous predators and your Blister Beetles were at some point feeding on the blossom in the photo. These Blister Beetles match an image on BugGuide of Lytta stygica, but a comment posted by Joyce Gross claims: “There is another beetle, Lytta chloris , which looks very much the same as Lytta stygica . But according to specimens I looked at, Lytta chloris occurs a bit further north, and more specifically, according to John Pinto, Lytta chloris doesn’t occur south of the Tehachapi Mountains.” We are concluding that your specimen is probably Lytta chloris unless Lytta stygica occurs further North in addition to its Southern California range. Since we brought up the carnivorous versus phytophagous or plant eating diets, Blister Beetles are quite a rarity in the beetle world. Though diets of immature and adult insects tend to include different foods, carvivorous larvae usually grow into carnivorous adults and phytophagous larvae grow into phytophagous adults. Many larval Blister Beetles are flesh eating, with grasshopper eggs being a choice food, while the adults feed on leaves and blossoms.
Letter 6 – Mating Blister Beetles: Genus Lytta
Mating black blister beetles
Great website you have there – here’s a contribution to your bug love page: these lovely insects swarmed a bush in my back yard in New Maryland, N.B. and proceeded to gorge on the blossoms and have a huge orgy at the same time. The proceedings went on for about 24 hours, after which all the blossoms were gone and everyone went away satisfied! Good thing I didn’t handle any of them as I did not know what they were at the time! Kathy Power
Hi Kathy,
Your wonderful photograph depicts Blister Beetles in the genus Lytta, as evidenced by the bead-like antennae, but we are not certain of the species. Perhaps Eric Eaton can provide the exact species.
Letter 7 – Mating Blister Beetles
Mating blister beetles
Fri, Oct 24, 2008 at 10:31 AM
Hey fellows, love the new website design! Here are the mating blister beetles from Shilo, Manitoba, Canada
Sherry
Shilo, Manitoba, Canada
Letter 8 – Mating Blister Beetles and SPAM Blockers
Unknown beetles mating on wooley sunflower
Mon, Apr 20, 2009 at 5:19 PM
Dear Bugman,
I found these beetles mating? on Wooley Sunflower Eriophyllum lanatum 4/20/09 on my hike of the Stevens Trail in Colfax, CA. Can you help me out with id?
Thanks, Cyndi
Sierra Nevada Foothills in Colfax, California
Letter 9 – Mating Blister Beetles
black with red stripes
August 23, 2009
I’ve found a half-dozen or so of these guys crawling around behind the barn, although it might be a mistake to refer to them all as “guys”. they have five horizontal red stripes around a tapering body – maybe 3/4 to 1″ long. Head and legs are more like those of ants – little teeny wings (?) with a vertical red stripe. they can move really fast when they want to, but mostly just waddle around.
I’ve looked in all my available references and I’m stumped.
Nancy L.
western AZ at 5000 feet elevation
Letter 10 – Mating Blister Beetles
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/thread
Reader Emails
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Mating Blister Beetles
Steamboat Rock State Park WA red headed bugs
Hello,
Can you tell me what these bugs are that my daughter and son-in-law saw on a shrub on top of 800′ Steamboat Rock that rises above Steamboat Rock State Park on Banks Lake in Eastern Washington State just south of Grand Coulee Dam?
Thank you,
Genelle
Hi Genelle,
This photo of mating Blister Beetles looks like Lytta magister. In checking BugGuide, we found that all the images of this insect were from Arizona. We are getting a second opinion.
Ed. Note: September 9, 2018
We just posted a new submission for a Blister Beetle from Washington that resembles a Master Blister Beetle, and we believe that this documentation and the newly posted documentation are both Lytta vulnerata based on images posted to BugGuide.
