Wednesday, November 27, 2013

Some Insects/Arthropods You Should Be Thankful For

How much of this delicious bounty was influenced by beneficial arthropods?

As we sit down this Thanksgiving to our turkey, mashed potatoes, and stuffing (and of course gravy!), we often give thanks to various people and things that make our lives better. So in that tradition, here are some of the insects and other arthropods (in no particular order) that, throughout the year, enrich our gardens, homes and lives...many of which we would not normally acknowledge.

Paper wasps, hornets & potter wasps (Vespidae)

Paper wasps (Polistes sp.) may sting, but they also hunt down pestiferous caterpillars to feed to their young.
Though largely hated due their painful stings and sometimes aggressive nature, these wasps are very good at hunting soft-bodied insects in gardens. Their favorite food seems to be caterpillars, which are the bane of most garden plants. The truly social groups (paper wasps & hornets) have an entire colony to feed, so they often carry away numerous pests. However they also need to defend their many sisters, thus their stings. Maybe I should focus on potter wasps (Eumeninae), who are solitary but also provision their mud pots with several caterpillars for their young to feed on. While they can sting, they are not aggressive like their social cousins. There are also several groups of solitary hunting wasps (Sphecidae) that give their young paralyzed caterpillars, further solidifying wasps as beneficial predators.

A potter wasp's (Eumeninae) pot is getting ready to dry. The small hole in the top is big enough for mother wasp to add a number of paralyzed caterpillars before sealing it off for her young to feed.

Parasitic wasps

A minute wasp (Aphelinidae; approximately 1 mm long) perches on its tiny host - a scale insect.
These usually minute wasps don't sting us, nor are they often seen by us. However, their effects on pests are immeasurable (figuratively - there are certainly studies that have been done to measure their impact). Most lay eggs within a host, which hatch into tiny larvae that feed on the poor organism from the inside. Others attach to the outside of the host, slowly sucking it dry. There are several groups of Hymenoptera that do so, including the large superfamilies Ichneumonoidea (Ichneumonidae & Braconidae) and Chalcidoidea (many families). Along with wasps several other groups of insects, notably flies (the family Tachinidae for example), have members that parasitize pests.

This hornworm caterpillar (Sphingidae: Manduca) is on its last legs. Its parasites (a species of Baconidae) spin white cocoons after emerging, from their host.

Pollinators (and not necessarily the ones that come to mind)

This false blister beetle (Oedemeridae: Heliocis repanda), like many beetles, loves nectar and thus also comes in contact with pollen which it may transport to many flowers.
I am sure you have already thanked butterflies and bees (both honey and bumble) for pollinating the plants we need to survive and enjoy looking at. However, there are numerous other insects that transfer pollen from flower to flower. Beetles, flies, bugs and even earwigs can be pollinators . In fact, any insect that visits flowers has a chance to pollinate. One of my favorite pollinators (as it should be yours as well) is a genus of tiny little biting midges (Ceratopogonidae). Without some of these [sometimes nasty] flies, we would not have one of life's greatest foods - chocolate! These flies are the only things that pollinate the cacao plant (Theobroma cacao), being small enough to fit inside the diminutive flowers.

Even earwigs (Dermaptera) enjoy nectar and pollen every once in a while. This one is covered in pollen which will likely rub off on another blossom, propagating the plant.


Larval black soldier flies (Stratiomyidae: Hermetia illucens) are powerhouses of decomposition, frequently obliterating compost waste.
Yes flies (Diptera) are sometimes annoying. And many transmit diseases or are pests. However, a large percentage of flies breed in decaying organic matter as larvae. This huge clean-up crew is responsible for devouring both rotting animal carcasses (which would be fun to have hanging around, right?) and vegetable matter. Proof of the latter can be easily seen by those who compost their yard waste and table scraps. Without flies we would be knee-deep in a putrid, bacteria-ridden mess - not something that would be good for your Thanksgiving appetite. Some flies are also important predators or biological control agents of weeds, to name a few good deeds done on two wings.

Energetic and beautiful, long-legged flies (Dolichopodidae) scour leaves to hunt down small insects including many pests.

Dung beetles

Even small dung beetles like this Onthophagus tuberculifrons can help bury dung and keep the ground clean.
As with flies cleaning up decaying matter, dung beetles get rid of another resource we find disgusting - excrement! These busy beetles (mostly Scarabaeidae) eat and bury dung for their young to feed on, effectively removing the foul substance from the ground surface. This has long been know to aid in pasture health by allowing grass to grow, aerating soils, destroying the breeding grounds of pest flies and worms, and returning nutrients to the soil. Instances where dung beetles are lacking have proved highly detrimental to natural and production ecosystems. Some are also quite beautiful and have amazing behaviors too.

The rainbow scarab (Phanaeus vindex) is one of our most beautiful beetles, despite spending a large amount of time covered in dung or underground. This male also has an impressive horn.

House centipedes

Although only a wee baby, this house centipede (Scutigeridae: Scutigera coleoptrata) is a fierce predator in the home.
Surprised by this? Despite their frightening speed and creepy leggyness, these centipedes (Scutigera coleoptrata) are good at hunting down and devouring household pests like flies and cockroaches. Though venomous, they rarely bite and most often use the venom to subdue things you really should be afraid of.


This fire ant (Solenopsis) is removing soil from its nest. Colonies of fire ants can be a good thing for your garden.
Again, although there are some ants that are not so great - those that sting and tend pest insects come to mind - many species of ants are very good at cleaning up waste, planting seeds and eating pests. For example, though fire ants are loathed for their stings, they can be very effective predators of crop pests. They are also effective, like earthworms and dung beetles, at aerating and churning massive amounts of soil.


Just kidding! There is really nothing good I can say about ticks. Though I respect them for their fortitude and tenacity, there is really no good reason for them to exist except to suck blood and transmit diseases (which they really can't be blamed for - pathogens just love to use ticks to spread).

Final thought
There are many arthropods that directly or indirectly benefit us and the ones listed above are just a starting point. Almost every group can have some quality that deserves our thanks - you just have to observe them in your garden or read the latest information to get a good idea of who the good guys are. It is also good to remember that "beneficial" is in the eye of the beholder - the advantages of arthropods must be weighed with the situation (e.g. some pests can be beneficial and vice versa).