Scary Bugs (And Why You Shouldn’t Be Afraid)

Eek! It’s a bug!

I know most folks don’t like creepy-crawlies. Bugs aren’t their thing. Mine, yes, but this is what I do – help people deal with garden pests and protect good bugs.

Some good guys do look scary, like something out of a sci-fi movie with spikes and fangs and ridges and crazy colors.   

But looks aren’t everything. In most cases, these are good bugs – what we call beneficial insects – that help to control the few bad dudes in your garden.  

Let me introduce you to a few bug friends that aren’t beauties but do a beautiful job of controlling harmful pests.  

Assassin bugs get a bad rap simply because of their name. We’re talking James Bond, right?  

an assassin bug is a cloudy-gray color with a hump on its back
Scary-looking assassin bugs are efficient predators. Photo: Photo: Johnny N. Dell, Bugwood.org 

That’s a good thing. Assassin bugs are efficient predators, but boy, do they look scary. Battleship grey with spikes down their backs, they look like they’re wearing armor.  

But the battle is mostly one-sided. Insects that cross an assassin bug’s path likely will get skewered by its lance-like mouthpart and slurped dry.  

Stop shuddering. There’s an upside. 

Assassin bugs eat almost any bug, making them ecological balancers that keep insect populations in check. Plus, they enjoy snacking on Japanese beetles, the scourge of many a garden.

Cute and beneficial, the ladybug lies at the other end of the beauty spectrum. But as youngsters, ladybugs resemble tiny orange and black alligators which often get squished because they look like they are Up To No Good.  

a lady bug larva is black and organge and resembles a miniature alligator
Spiky ladybug larvae control aphids and other pests. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Not true. These are good guys who consume even more aphids, spider mites, scales, and other baddies than adult ladybugs. In fact, one ladybug can eat over 5,000 aphids in its lifetime. 

Many juvenile insects look nothing like their more familiar adult counterparts. So stop before you squish or spray. Snap a photo or bring a sample to your local Extension office. Most likely it’s an ally you want to protect.  

You can find your Maryland Extension office on our website. Or reach out to the certified horticulturists at our Home & Garden Information Center for help. Send a photo or question to them at Ask Extension.

Wasps get a bad rap, too, with much swatting and shrieking and fear of The Stinger. Only females have those – they’re modified egg-laying organs – and they aren’t likely to use them unless threatened.  

But most wasps are beneficial, preying on bad bugs or laying their eggs on them to feed their young. Plus, they are pollinators, protecting 1 in 3 bites of food we eat. 

a wasp visiting a white-flowering plant
Scoliid wasps lay their eggs on Japanese beetle larva. Photo: Shanon Wolf

Spiders aren’t insects – they have 8 legs, not 6 – but they give many people the willies. But spiders also are beneficial, quietly and efficiently consuming many harmful insects.  

a black and yellow garden spider in its web
Argiope spiders provide free pest control in the garden. Photo: Heather Lawhead

Beauty isn’t everything. An army of not-so-lovely-but-useful insects are your allies in the garden, protecting your plants from the 1 in 10 bugs that are actually harmful. 

So think before you squish or spray. Get us a photo or sample. We’ll identify it and give you management tips that deal swiftly with bad bugs while protecting beneficial insects. 

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension.

This article was previously published by Herald-Mail Media. Read more by Annette.

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
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