Biological pest control: parasitoids

¿Hablas español? Aquí esta una traducción: Control biológico de plagas: los parasitoides

Parasitoids are natural enemies of pests that, like predators (ladybugs and flower flies) can help us keep pest populations at bay or eliminate them from our gardens.

Parasitoid or parasite? Let’s learn the difference between these terms

Before saying more about this group of natural enemies, let me tell you that it is very common to confuse the term “parasitoid” with the term “parasite.” Parasites and parasitoids have in common the need for a host for their development. The difference between the two types of organisms is that parasitoids kill their host to complete their life cycle. That is, the parasite can live at the expense of the host without having to kill it, while the parasitoid ends up killing its host upon completion of its life cycle. Parasites are generally known to be annoying and even transmit diseases to animals, plants, and humans, while parasitoids are beneficial insects, as they help us control pests.

What is a parasitoid?

Parasitoids are insects that insert their eggs into the body or egg of another insect (host) in order to complete their life cycle. Parasitoids go through complete metamorphosis, four different stages of development: egg, larva, pupa, and adult. To finish their development, the parasitoids must feed on their host, and the females first deposit their eggs in their host. As soon as the parasitoid egg hatches, the larvae begin to devour the tissues of their host. Once the larvae reach a certain size, they become pupae, after which the adult emerges, killing the host.

Parasitoids can be classified according to their oviposition (egg-laying) behavior. Endoparasitoids are the parasitoids that lay their eggs inside the body or egg of their host. In contrast, ectoparasitoids oviposit on top of the body of their host, that is, on the surface of their body. To see these fascinating creatures in action you can, watch a video of endoparasitoids and one of ectoparasitoid activity.

Life cycle of an ectoparasitoid (adapted from Presa-Barra et al 2020)

life cycle steps of an ectoparasitoid

Life cycle of an endoparasitoid (adapted from Presa-Barra et al 2020)

life cycle steps of an endoparasitoid

Some ways to identify signs of parasitism in our gardens

Observing parasitoid pupae on top of pests

parasitoid wasp pupae on a caterpillar
As ectoparasitoids pupate outside their host, pests can sometimes be seen carrying “sachets” (the pupae in their cocoons) over their body, as seen in this photo. In this case, the parasitoid deposited many eggs on the caterpillar, which eventually pupated. After several days, those pupae will emerge as adult parasitoids. Photo: Mike T.

Observing colonies of aphids

aphid mummy
Sometimes we can observe aphids that look empty and have an opening in their body, as in this photo. This indicates that an endoparasitoid first parasitized and then emerged from that aphid. In this case, the parasitoid deposited an egg inside the aphid and completed its cycle inside it. Finally, it emerged creating a hole in the dead aphid. Photo: NY State IPM program.

Diversity of parasitoids

Most parasitoids belong to flies (Diptera) and wasps (Hymenoptera). Thousands of species of parasitoids are known from both groups, with Hymenoptera containing the most identified parasitoid species.

Parasitoid flies: Tachinidae

Within the group of parasitoid flies, the Tachinidae are one of the most important groups for biological pest control. Most of these flies are larger than a housefly, 2mm-20mm. This group is very diverse and some Tachinidae are very hairy and dark in color, while others may appear pale to the naked eye, or have bright colors such as yellow or orange. Most Tachinidae are endoparasitoids. Tachinidae attack leaf caterpillars, fly larvae, adult beetles, and other pests much larger than themselves. In this video, you can see how a Tachinidae fly parasitizes a caterpillar.

Parasitoid wasps: Mymaridae, Braconidae, and Ichneumonidae

Parasitoid wasps are one of the most studied parasitoid groups for biological pest control.

The Mymaridae are a group of very small parasitoid wasps that specialize in parasitizing eggs. All members of this group of parasitoids parasitize eggs of bedbugs, beetles, and pest flies in our garden.

very tiny wasp
These parasitoids are minuscule. To give you an idea, this photo shows a Myrmaridae on a person’s finger. Photo: gbhone

Ichneumonidae and Braconidae

These groups of parasitoid wasps are much larger than the Mymaridae. Most are around 1cm long, with 5cm being the record for the largest parasitoid wasps in North America, which belong to the genus Megarhyssa sp.

The Ichneuomonidae and Braconidae attack several pests including caterpillars, fly larvae, and aphids as shown in the image below.

an attach by Ichneuomonidae and Braconidae wasps
Parasitoid of the group Bracononidae attacking aphids. Photo: UGA CAES/Extension

Some of these parasitoids have a very long ovipositor, such as that of the species Megarhyssa macrurus, which is used to deposit its eggs in pests that are hidden between leaves or inside the trunk of trees. In this video, you can see Megarhyssa macrurus ovipositing on a tree trunk to attack a larva.

a wasp with a long ovipositor
Parasitoid wasp with a long ovipositor. Photo: gailhampshire

How to help parasitoids

There are several very effective practices for the conservation of parasitoids in our green spaces.

  1. As much as possible, avoid using broad-spectrum pesticides to control pests, as most of these also affect parasitoids. If you decide to use pesticides, opt for specific options and always use them as directed on the label.
  2. Diversify your planting (increase the types of plants grown) so that parasitoids have more spaces available to survive, a variety of prey to feed on, and/or nectar to supplement their diet. Crop diversification offers the presence of a wide variety of prey, which parasitoids can attack and use to survive when there are no pests in their green spaces. By increasing plant diversity, one provides parasitoids with resources that keep their populations in high numbers, which helps them better control our crop pests as soon as they appear.
garden plot of Swiss chard and flowers
One way to help parasitoids is by diversifying crops, as seen in this garden, where you have combined vegetables and flowers. Photo: W. Murphy

In the case of a pest invasion, you also can acquire parasitoids in local insect hatcheries or on the internet and release them into your garden. This will lead to pest control and in some cases the establishment of those parasitoids in your garden, which can help fight future pests. It is important to note that for this to work, it is important to carry out the two other practices already mentioned above.

Find out more

Presa-Parra, E., Hernández-Rosas, F., Bernal, J. S., Valenzuela-González, J. E., Martínez-Tlapa, J., & Birke, A. (2021). Impact of Metarhizium robertsii on Adults of the Parasitoid Diachasmimorpha longicaudata and Parasitized Anastrepha ludens Larvae.  Insects, 12(2), 125.

Patt, J. M., Hamilton, G. C., & Lashomb, J. H. (1997). Foraging success of parasitoid wasps on flowers: interplay of insect morphology, floral architecture and searching behavior.  Entomologia experimentalis et applicata, 83(1), 21-30.

Wäckers, F. L. (2004). Assessing the suitability of flowering herbs as parasitoid food sources: flower attractiveness and nectar accessibility.  Biological control, 29(3), 307-314.

By Darsy Smith, a Ph.D. student in the Department of Entomology at the University of Maryland, College Park. This article was published originally on the department’s Spanish-language blog, Extensión en Español.

Celebrate National Moth Week

A moth feeding on nectar of a purple  verbena flower
Hummingbird Clearwing. Photo: M. Talabac

The last full week of July is National Moth Week, and I encourage everyone to take a closer look at the vast diversity of moths that fill our natural world. Butterflies and moths belong to the same insect group, but moths far outnumber butterflies in species diversity. Since many moths have muted colors or fly at night, we’re largely unaware of this bounty. Let’s take a whirlwind appreciation tour of the group to illustrate the amazing, bizarre, and quirky features of this major insect order.

Moth adults come in all shapes and sizes, and like butterflies, wings are their most prominent feature. There are “micro-moths” whose wingspans are less than an inch, and giant “silk moths” up to 6 inches, making them the largest moths in North America. (Our native silk moths are not closely related to true silk moths, but they got the name because people thought they could be farmed for silk.) The wings of some moths look like mere slivers, seemingly insufficient for flight, while others are tucked around their body so they look fairly cylindrical. Some lay so flat at rest with their wings spread that you’d swear they were two-dimensional.

Some species unabashedly bear flashy colors and patterns in broad daylight because they’re chemically defended, often using substances the caterpillars ingested from their host plant, similar to how Monarch butterflies use milkweed toxins. Giant Leopard Moths, white with bold black leopard spots and a metallic blue abdomen, can exude golden droplets of a distasteful substance from their shoulders when disturbed. Wasp-mimicking species use warning colors to gain protection – few predators want to risk a sting – while other species use a different tactic and pretend to be inedible objects, like lichen, twigs, dead leaves, or even bird droppings.

Other moths hide vivid wing colors until prodded, their forewings camouflaged and covering their body at rest. When disturbed, they flash their colorful hind wings or expose eyespots that stare back at the predator. These bright patterns or eye-like designs startle a predator into rethinking an attack, making the moth appear too big to prey upon or giving it time to flee.

For seemingly defenseless creatures (no stinger, no jaws, no horns or sharp projections, and a soft body), adult moths use some clever strategies for survival. Great camouflage is the baseline strategy, but some moths can hear ultrasound produced by hunting bats. When the flying moth hears a bat homing in on it, the moth drops out of the sky and disappears from the bat’s radar. Milkweed Tussock Moth adults actually click back ultrasonically at a pursuing bat as a warning about their distaste, in case the bat ate others like it and regretted it.

It can be surprisingly hard for our dexterous fingers to pick up moths and densely-bristled caterpillars, so you can imagine other animals without hands have an even harder time if their strike isn’t spot-on. As with butterflies, wing scales can be slippery and may shed as the wings are grabbed, allowing the moth to slip away and escape.

Blooms that attract moths tend to be white or pale in color, or pink, dull red, or purple, and often have a strong, sweet scent, especially at night. As with butterflies, they prefer bloom shapes or clusters of flowers that provide a “landing platform” where they can sit and sip nectar, though some moths will hover while feeding instead. The sphinx moth group, which includes clearwings and the adults of hornworms, are the classic examples of “did I just see a small hummingbird?” At rest, they have a silhouette more like a fighter jet.

Moth caterpillars have a dazzling array of colors, patterns, and shapes. A few are spiny and have skin-irritating properties, like the cute Saddleback caterpillar that looks like a brown terrier wearing a neon-green blankie. I have been stung multiple times over the years by accidentally brushing up against them when handling plants because they’re inconspicuous when sheltering underneath leaves. It sure smarts for a few minutes, but I still think they’re beautiful and adorable.

Some caterpillars resemble a walking toupee or dust bunny, like the flannel moth caterpillars (another no-touch group), or a fringed carpet that blurs their body outline. Slug caterpillars include species whose body fringe looks made of spun glass (as one species is so-named) while the Monkey Slug looks like some sort of faceless alien Muppet with a fun hairdo and a herky-jerky gait. (Don’t touch that one either.)

Slug family caterpillars also include featureless speed bumps, with no discernable head or legs unless flipped over. (No slime on these slugs though, thankfully.) Maybe they’re trying to mimic leaf galls, though it’s an odd choice to me if so, since galls can be attacked by parasitoid wasps or foraging birds. Some giant silk moth caterpillars have colorful knobs on their body or spiny horns that look like they belong in a punk-rock band. (With a name like Hickory Horned Devil, you can’t go wrong.) The caterpillars of other moth families have multi-hued patterns, detailed stripes, marbling, zigzagging squiggles, or big eyespots above their heads that mimic a snake staring you in the face.

Inchworms are aptly named because their slender, long bodies inch along in a loping gait. Many disguise themselves like leaf stems or twigs when not feeding by standing on their hind legs ramrod-straight and freezing like a living statue performer. (This family’s name is Geometridae, which means “earth-measurer.” And they do, once inch at a time.) One family member, the Camouflaged Looper caterpillar, decorates itself with bits of leaf or petal that it’s eating, becoming a walking parade float of flair. As it matures and eats new things, its costume changes.

brown and black moth with orange marks on its body
Tobacco Hornworm

While a minor handful of moth caterpillars are home or garden pests or ravenously gregarious feeders, the great majority do not cause us humans any trouble. Plenty of caterpillars and adult moths alike feed hungry birds, bats, beneficial wasps, predatory bugs, and other organisms that help keep our ecosystem in balance. With over 2,500 moth species documented in Maryland to date, you could make a long-term hobby out of cataloging all the species found in the smallest of yards. (A good gateway to developing an interest in all of the other wondrous insects you’ll encounter in the process!)

Want to explore more about moths? Check out the National Moth Week website for tips on finding moths, activities for kids, and more.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun. All photos in this post are hers. Read more by Miri.

The more the merrier: community actions for pollinators

bumble bee on a purple coneflower

Besides it being the month when summer starts, June is a great month because it is when Pollinator Week happens! 😊

Tagging along with that week, in today’s post I want to talk about some actions you can take with(in) your community to help pollinators! Because, if we want to help pollinators, a very valid and effective way to amplify your actions is to get others on board! Here, a non-extensive list of ideas.

1. Become a Bee City

Ask your City or Campus to become a certified Bee City or Bee Campus USA. Bee Cities and Campuses are certifications that cities and campuses across the USA can obtain if they implement a series of actions (“commitments”) established by the Xerces Society. Once these actions are done, the City or Campus in question becomes certified as a pollinator-friendly space. The types of actions outlined are really activities that lead to increasing education on pollinators and pollination, to improving pollinator habitat on the institution’s land, to promoting actions in the way that the institution functions that may allow for increasing pollinator support (see here for city commitments and here for campus commitments). Becoming a Bee City or Campus is not hard, and most institutions say yes if their members ask. If you think this is something you would like your City and/or Campus to do, reach out to your representatives or leadership and get them on board! And to have an idea of what cities and campuses are already involved, take a look at the Bee City USA affiliates.

2. Organize a Pollinator Week Event

Pollinator Week is a National event organized by the Pollinator Partnership and includes many possible actions that lead to increasing pollinator survival and/or awareness. This year, Pollinator Week will be happening June 20-26. One can participate in activities already organized by others, or one can propose and host an activity! If you would like to get together with your community and organize an event, do it, and then submit it to the Pollinator Week event list! That way, others will know about it and will participate as well! To submit (or participate in) an event, go to the bottom of the Pollinator Partnership page.

Here are some activities happening in Maryland: bee hotel building workshop in College Park, MD, webinar in Greenbelt, MD, pollinator catch-and-release in Saint Leonard, MD, and several activities in Howard Co., MD.

Pollinator Week, June 20-26, 2022 logo

3. Ask your city to host a No-Mow Month in early-spring

Early-spring pollinators emerge usually when very few plants are flowering, meaning that the early spring is a critical time for these pollinators. In human-occupied landscapes like cities or suburban areas, a lot of the landscape is occupied by lawns, which can provide some flowers early in the spring. No-Mow Month (usually April or May, depending on the city’s conditions) is an action that seeks to allow the availability of the early flowers in lawns so that local pollinators can survive during the early spring. Once other plants in the landscape start flowering (usually at the end of April in most of Maryland), the lawn can be mowed with this not negatively affecting pollinators.

It is important to note that this action is based on voluntary participation, meaning that participants opt-in (instead of being mandated to do it). This action has been shown to be effective in increasing pollinator diversity and abundance in regions where it is implemented, and is not associated with excessive lawn growth because it occurs so early in the season. Further, it can be strengthened with native plantings, which can boost its effects and also support local landscapers during the reduced-mow month. Localities where the action has been implemented tend to have high adoption rates, increased nature awareness, and willingness to further support biodiversity around homesteads, with no- to very-reduced vermin occurrence.

This action usually requires some temporal amendments to City Code (e.g., to ensure that participants will not be penalized if their lawns surpass the maximum allowed height during the no-mow month) so it needs approval by City Councils. Although this may sound really complicated, it is not, and several Cities in Maryland have implemented this program very successfully during the month of April (see here for College Park, MD, and here for Greenbelt, MD), following Appleton, WI’s trailblazing action. If you think this is something you would like to implement in your community, get in touch with these cities’ Bee City USA committees so they can share their expertise, and then contact your representatives to ask them to adopt this action where you live!

No Mow April Collage Park sign

4. Ask your community to establish pollinator-friendly plants and nesting resources

Communities can also support pollinators through the way they decide to landscape their land. Requesting your community leadership to implement pollinator-friendly gardens and offer nesting resources for pollinators (e.g., bee hotels, create small wild spaces) is a really good way to help pollinators at a larger scale. To do this, you can get in touch with you City/Town Horticulturist and/or Public Works people, and request this. If you would like to implement this in your neighborhood and on private land, you can coordinate with your neighbors and create plots of native plants or small nesting areas in everybody’s green spaces. A very effective way to do this in Maryland is by establishing a neighborhood Green Team. If you would like to know about how to do this, take a look at this page of recommended native plants and this list of native plants that do well in our area.

Chart listing easy-to-grow native plants that support pollinators

5. Ask you city/town/neighborhood to adopt an IPM plan

Although we tend to think about helping pollinators only by planting flowers and maybe creating nesting spaces, pollinators also can be helped by the way we manage our landscapes. For example, herbicides and pesticides can be sometimes very harmful to pollinators, or cutting plants at certain times of the year can really negatively affect them. Reducing the use of pesticides and herbicides, or changing the way we manage our own private land is one possibility. However, cities, towns, neighborhoods, schools, and campuses also manage their public lands! For that reason, they can also implement actions to manage spaces in ways that support pollinators.

chart explaining Integrated Pest Management in 5 steps

A very good way to institutionalize this is by requesting these institution to implement Integrated Pest Management (IPM) plans. IPM is a way of controlling pests and increasing “beneficial” organisms in a given space by means that reduce the use of pesticides and herbicides. These plans establish a framework that allows institutions to still control pests and diseases, while reducing the negative impacts on biodiversity that some conventional practices have. These plans can be very general or very specific, and if your institution does not have one, it may be time to ask them to implement one! To do this, get in touch with your institutional horticulturist or your government representative. Here are some examples: city, campus and school district plans.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

Bees to look out for: leaf-cutter bees!

Spring is well-established and many flowers have already started to bloom. In my garden, I have seen several sizes and shapes of insects visiting flowers, going from small flower flies to butterflies, to very tiny and shiny, fuzzy large, and very large bees. And with all these flying organisms starting to come around us, I thought today would be a really good time to introduce you to some really cool bees that are very common in our area: the leaf-cutter bees!

What are leaf-cutter bees?

As its name suggests, these are solitary bees known to cut leaves (now you may be thinking, “duh, I could have guessed that without a blog post”, but bear with me!). These bees belong to a very large family of bees called Megachilidae, which is present on all continents except Antarctica and well-represented in our region.

Like most solitary bees, the female of leaf-cutter bees builds nests with small brood cells, in each of which a food provision is left and one egg laid. And this is where the “leaf-cutter” name comes from. When building their nests, many of these females line their brood cells with specific materials, in particular plant tissues. In fact, many of the species are known to cut leaves and/or petals to line their nests, using them to stabilize the brood cells, and likely to provide protection to the larva and the food provisions. In a fascinating way, it is suspected that these bees are able to exploit the antimicrobial effects of certain compounds present in these flowers and leaves, indirectly using them to protect their offspring until they finish their development in the nests.

If you ever saw neat and relatively large holes that seem to suddenly pop up on certain plants in your green spaces, it is very likely that they were made by some of these bees that may be nesting close to you! If you keep an eye out on those plants, it is very likely that you will end up seeing these busy bees carefully cutting, then rolling, and finally flying away with the neat plant circles!

Female leaf-cutter bee cutting a leaf
Leafcutter bee nest and brood cells made with leaf pieces
Megachilids are known for cutting leaves that they use to line the brood cells of their nest. Note that here the nest is in a soil mound and each brood cell is completely covered with leaves but capped and separate from the neighboring cells. In this nest, each cell contains one egg. Photo: E. Soh.
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How do pollinators find plants and flowers?

As we know, pollinators help plants spread their pollen among flowers, and many plants do indeed need them to be able to reproduce and set seeds. We also know that by planting flowers and providing nesting habitats, we can help pollinators’ populations and thus assist with plant pollination. However, how do pollinators find plants? In this post, we will talk about that topic, which can help us become even better at helping pollinators and the plants they pollinate.

The big picture – pollinators need to be in the area

In order for pollinators to find plants, pollinators need to be present in the general region. In fact, although the vast majority of pollinators can move and travel from place to place, all of them have limitations on the distance they are able to travel. For example, hummingbirds can travel for miles (in Maryland, they are migratory), while large bees are able to travel relatively large distances for an insect (~500m-1km), and smaller insects will not be able to travel that far. This means that if, say, we lived in the middle of a very developed area with very few pollinator-friendly resources (few flowers, lots of cement, no green areas, etc.), planting a pollinator garden will attract few pollinators at first. This is due to the fact that it is likely that few pollinators are present in that area, and thus it will take a while for certain groups to arrive and establish in our garden.

It is for this reason that many communities tend to try to establish joint pollinator-friendly actions, and encourage many people in the region to participate (e.g., becoming Bee City USA-certified, creating “pollinator highways or corridors”). By increasing the regional number of pollinator-friendly resources, the whole region becomes more pollinator-diverse, and any supplementary action is more likely to improve pollinator support. As we talked about in a previous post, if you are interested in promoting pollinator-friendly habitat on your property, it may be a great idea to talk to your neighbors or your City, and see if others may also want to participate. In terms of pollinator-friendly activities, the saying “the more, the merrier” is very much true!

pollinator habitat sign in a garden
Pollinator-friendly actions are very effective when they are coordinated across regions. Photo: A. Kokai.

The local picture – different pollinators prefer different plants

As we mentioned in other posts, not all pollinators are made equal, and this is also true in terms of what plants will be found by what pollinators. For example, hummingbirds tend to visit tubular and reddish flowers, while syrphids prefer open flowers, and bees tend to visit flowers that they can access with their mouth parts (see this post to learn more). 

These floral preferences are due to the different pollinators’ abilities to see different colors, the presence of specific attractive floral scents in different plant species, and the ability of different pollinators with different body and mouth part shapes to handle and feed on flowers, and the matching of pollinator presence and flowering time. The practical consequence of this is that if we want to help many different pollinators find their preferred plants, it is necessary to grow different types of plants in our green spaces. By doing this, we would always provide resources that will be preferred to at least one pollinator, and by providing different types of resources, we can make sure that many different types of pollinators are supported by our plants. In order to do this, there are different floral mixes that exist that allow us to plant diverse floral resources appropriate for our region, which lets us build a diverse and welcoming floral bed for many pollinators.

Planting diverse floral resources will attract many different types of pollinators. Photo: C. Celley/USFWS.

The super-local picture – pollinators need to see the plant to access it

This will sound silly, but pollinators need to be able to have access to the plant to find it. For example, if a plant is not clearly displayed or hidden by many other plants or structures, it will be hard for pollinators to find it… even if the pollinator is present in the area and the plant in question is a preferred plant. This means that for us to help pollinators, we need to make sure that our plants are findable by the pollinators. Picking appropriate parts of our green spaces to plant our pollinator-friendly plants is thus key! For example, plants that require full sun to grow should be planted in those conditions and not under the shade of other plants or behind structures.

To know what these specific conditions are, there exist several resources (for example, see this useful and simple resource (PDF) published by the City of College Park, MD). These resources allow us to pick the best growing spot for our plants, making them easily findable by their pollinator friends.

Finally, pollinators are more likely to find plants if there are several of them! This is particularly true for smaller herbs, which may not display many flowers. By increasing the number of plants planted in an area we are also making the plant species more easily findable to the pollinators.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí. Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

A larva with light: Can you guess what insect this is?

The end of June brought a very exciting event. As I was cutting holes in the landscape fabric to plant some late-season flowers in my high tunnel, I found several larvae of a great beneficial insect! I guess it was the perfect environment, as I found at least 10 that evening. It was moist, although in the photo it looks pretty wet because I was running my drip irrigation water. When I found it, I was so ecstatic that my 5 year old daughter thought something bad had happened with all my yelling! I then shared a photo with my whole family. Needless to say, no one else seems to get quite as excited as I do about good bugs. Below are some photos from that special evening. Do you know what it is? Have you ever seen one? I’ll give you a few clues so you can see if you know what it is.

  1.  As larvae, they are incredible predators of many ground dwelling garden pests, like snails and slugs! 
  2. The adult form is a beetle so they have a complete life cycle —  egg, larvae, pupa, and adult!  
  3. Size: approximately ¾’’. 
  4. The larvae and adults have bioluminescence, an amazing ability to “light up”.  

That’s right, the last clue should have given it away. This is a larva of a lightning bug.

Did you know lightning bugs, also called fireflies, are actually beetles? They bring joy to everyone with their beautiful displays of flashing lights. Lots of additional information about them can be found here: https://www.xerces-dev.org/endangered-species/fireflies/about

Adult beetle. Photinus pyralis, known by the common names common eastern firefly and big dipper firefly

So where could you find these awesome critters in your landscape? Most species have at least a 2-year life cycle, and 95% of their life is in larvae form. Most adults only live 2-4 weeks. They like moist, dark areas near the soil surface, since that will be where they find their next meal.  Sometimes they even hide in the crookes and crevices of tree bark. 

Below are some actions you can take to create a habitat to attract fireflies. This information is provided by Firefly.org.

  1. Eliminate light pollution in your landscape (turn off unneeded outdoor lights, keep your curtains drawn). Fireflies use their flashing patterns to attract mates. Extra lights can disrupt their ability to find each other. 
  2. These critters thrive in wet areas around ponds, streams, wetlands, and swampy areas.  Add a water feature to your landscape if you do not have natural sources. 
  3. Avoid pesticides, especially broad-spectrum insecticides which kill many types of insects indiscriminately (even the beneficial ones). 
  4. Do not over-mow your lawn (taller grass gives fireflies a place to hide during the day). 
  5. Dead logs and leaf litter provide great habitat, so try to create an area in your landscape that has a  natural area with these materials. 
  6. Plant native trees and native grasses to provide shaded habitat. Shade helps conserve soil moisture which attracts food sources for firefly larvae.  

My family is lucky to live in a rural area near a small stream and swampy area, so we are blessed to see a wonderful display of fireflies for several months each year. Check out my blog from last summer:  Firefly or Lightning Bug: You Decide!  

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland, edited by Christa Carignan, Coordinator, Home & Garden Information Center, University of Maryland Extension. See more posts by Ashley and Christa.