——–2013 Growing Season Educational Campaign:Beneficial Insects——–
-Lori Brewer,Jason Dombroskie,Abby Seaman,Betsy Lamb
1) I took notes, but I only vouch for the notes within the limits of my ignorance and a little post-workshop research.
2) Generally I am not directly quoting anybody, unless you see quotation marks. All factual errors are mine!
3) Re: above-Corrections are appreciated!
We arrived in Binghamton a bit late, so we missed the welcome speeches and got right to entomology 101.
WHAT IS AN INSECT
It’s a critter with 3 body parts (head, thorax and abdomen), 6 jointed legs, 1 pair of antennae, a metamorphic life cycle and compound eyes. They have 4 wings or less. (Of course, this is awfully simplified). They are in the Phylum Arthropoda, Subphylum Hexapoda (6 legged),Class Insecta. Most living things are Hexapods, and most of these live on land. We saw a number of phylogenic trees with a great deal more detail than that flash by in the power point…
All the creatures we learned about are Arthropods, but not all are insects. For instance, spiders are in the class Arachnida.They have 2 body segments and 8 legs, so are not insects. Going forward, though, I will just use “insects” for everyone, though not “bugs”, since insects are not bugs-bugs are a kind of insect!
Considering that there are possibly 5 to 80 million insect species in the world, you can imagine that we were treated to only the broadest overview. In New York, about 16,000 have been described as of the 1930’s, and more are still being found.There is a huge variety in the modification of insect body parts, such as their mouths,legs & wings, in order to adapt to different sorts of habitats and environmental pressures. As Betsy described some of the sucking,chewing, rasping, grasping, swimming, piercing, lapping,flying, armor-plated possibilities, it became clear that understanding how they are built tells you a lot about an insect’s behavior. And if you understand what it does to survive, you are closer to appreciating its place in the garden.
In addition to the obvious superficial characteristics, there are many subtler ones,such as wing venation and genitalia. Fortunately for master gardener volunteers, most of our ID’s require less detail, though you’ll still want to have a good microscope on hand.
Insects have exoskeletons, which they have to moult in order to grow.Each moult is called an instar. All moulting is done by nymph or larvae-adult don’t moult, and therefore don’t grow.
In incomplete metamorphosis, there is no pupal state. The insect looks generally like the adult after each moult, as in grasshoppers.
Complete metamorphosis includes larvae and pupae between the egg and adult stages. Immature and adult stages look very different, and may occupy different positions in the ecosystem. An example of the complete metamorphosis is the butterfly. This brings up another reason to tread lightly when considering an insect a “pest”-there are no butterflies without leaf munching caterpillars!
Insects breath with spiracles (tiny holes in their bodies). These can be easy to see on the sides of caterpillars. Birds and other animals know this, and take advantage of it by taking dust baths to rid themselves of parasites.
Most adult insects have a single pair of compound eyes, and mouth parts used for many types of chewing or sucking. They are the only invertebrates that fly.
In addition to herbivores (phytophages) and predators, there are fungivores and detritivors (detritophages) – important composters in the ecosystem. Some insects are parasites or parasitoids. Parasites don’t kill their hosts. Parasitoids do.
Now that we know some basics about insects, how do we identify them? One technique is to use a dichotomous key, where you are given couplets to choose from that lead you on to the next pair. You have to have a pretty good specimen to follow these to the end. Another type of key is called Matrix based. With these you can choose the characteristic you want to look at, but as there are so many characteristics, these are hard to create. One you can check out is on the Lepidoptera of Canada.
Bug Guide is another recommended online site, which I was glad to hear, as it is one of my first choices when trying to identify a mystery insect.
MEET THE BENEFICIALS
“Out of the 800,000 – 1,000,000 species of insects that have been described so far, not more than 1,000 (about 1/10 of 1%) can be regarded as serious pests, and less than 10,000 (about 1%) are even occasional or sporadic pests. “ – Source: NCSU Extension
On the class outline, this section was called “Meet the Beneficials”, but really, we met everybody. Many families of insects have beneficial, pesky and neutral members, and all have a role to play in the environment.
Some insects may give us the creeps, and millipedes and centipedes are at the top of my list. Centipedes, in the subphylum Myriapoda, have 1 pair of legs per body segment. They are active predators, and capable of inflicting a bite. Millipedes have 2 pairs of legs per segment, are mostly scavengers or fungivores, and move more slowly than centipedes. They may roll up (think “pill bugs”).
Scorpions,ticks and spiders are Arthropods, like insects, but in the subphyllum Chelicerata, class Arachnida. Arachnids mostly have 8 legs, 2 body segments (a cephalothorax and an abdomen) and modified mouth parts.
Spiders are in the order Araneae. They are primarily predatory, though a plant eating spider was recently found in South America. Also the orb weavers consume their webs,and probably get nutrients from that and the pollen caught in it. Most are not dangerous. In fact, at a Science Cabaret in Ithaca last October,Linda Rayor from Cornell assured us that we do NOT have the brown recluse in New York State. We do have a poisonous yellow sac spider that is very common, so common that the self-professed spider lover directed us to kill every one we see…
ID can be difficult. Look for eye arrangement, number of claws, spines on the legs, and genital structures. The orb weavers tend to have big round bodies. Interestingly, the conspicuous white silken adornments in some webs reflect ultraviolet light, which attracts insects using the same techniques as flowers. It may also warn birds off. Crab spiders have big abdomens and large front legs. You’ve probably seen a common one in goldenrod flowers. Jumping spiders often have large eyes. There’s one that mimics an ant, and it’s been in New York for about a decade now. That would be a great identification test! Some spiders are active at night-try taking a walk with a headlamp when it is pitch black out, and maybe you can see their multiple eyes glowing back at you. Harvestmen (such as Daddy Long Legs) are Arachnids in the order Opilione. They have a single body segment & slender legs. They are predators, omnivores and scavengers.
Finally there are the Psuedoscorpios. They look like itsy scorpions, generally living under bark, but occasionally are found in houses or hitchhiking around on other insects. A number of people at the workshop had seen them-they are predatory but harmless to humans.
At this point we come to the Acari-mites & ticks. I’m not sure about scorpions, but nobody had anything good to say about the ticks, and most mites are considered pests. Except for the predaceous mites, which can be helpful in the greenhouse against spider mites, and red velvet mites. They have a complete metamorphosis, the immatures have 6 legs and they are EVERYWHERE. Try not to think about it…
Springtails are Hexapods in the order Collembola.They are mostly predators,detrivores,and fungivores, with a few phytophages, and are very abundant in the soil. Many are very small, but you may have seen so-called snow fleas blanketing the the snow in winter. They mate indirectly, the males scattering their spermatophores about for the females to conveniently crawl across.
In the order Odonata, Dragonflies and Damsel flies are predatory as adults, but even more so as aquatic nymphs. Dragonflies rest with their wings flat, damsel flies with the wings perpendicular over their backs.
Mantids have modified forelegs, leathery forewings and are predatory as well as cannabalistic. Outside of captivity, however, the males usually survive mating.
Lice, book & bark lice are scavengers and lichen grazers in the forests.
The true bugs are in the order Hemiptera. They are distinguished by their sheathed,sucking mouth parts, called “beaks”. They can tuck these up under their heads so they are not always easily visible. Most are phytophages, some are predatory, and some, like the bed bug, are parasites. The assassin bugs are Reduviidae, a family of mostly beneficial predators. Assassin bugs have hard exoskeletons to protect themselves from the stings of their prey. Try pinning one of these guys for exhibit case (oops-spoiler for the funnest part of the workshop!). Stink bugs are shield shaped, with an”x” being formed by the meeting of the hard over wings and transparent under ones. The brown marmorated stink bug is an invasive agricultural pest that is a major problem,and is hard to distinguish from our native species. They also invade homes, but shouldn’t be confused with the western conifer seed bug, an equally stinky but larger bug native to the Pacific coast. It’s minor pest of conifer plantations, and a major pest in my house. Though many of our native stink bugs feed on plant juices, some are predatory, even feeding on caterpillars.
The Miridae family are also true bugs. The tarnished plant bug and other agricultural pests are in this group, but the Minute Pirate Bug is commonly used successfully in greenhouses to control thrips, spider mites and aphids. Thrips are in Order Thysanoptera. They have fringed wings and fly well, but are easily blown around. They have an incomplete metamorphosis, laying their eggs in leaf tissue and pupating in the soil. Although many are considered major pests, some are actually beneficial,feeding on other insects or mites.
The insect order Neuroptera, or net-winged insects, includes the lacewings, mantidflies, antlions, and their relatives. They are predatory as adult and larvae. You may have seen lacewing eggs, perched distinctively at the end of their stalks.
The Coleoptera are the beetles, one of the largest groups of insects. The ground beetles (Carabidae) are mostly predatory. You might spot them by their square thorax.They live in the soil and under rocks. Bird watchers have their LBB’s (little brown birds), and entymologists have LBB-little black beetles-and lot of them.
Rove beetles are long & slender, with wings that are much shorter than their abdomens. Most are predators, and will eat almost anything that lives in the soil. Some, like the ones in our mushroom laying yard, can tip their abdomens up like scorpions. They are beneficial, and have no stingers.
Lady beetles are familiar beneficials, though most of the ones you see are actually from Asia, and may be displacing our native ones. They both perform the same job in the garden, though, especially as voracious larvae.
Hymenoptera are are also a large order of insects, and include the ants,bees,wasps and sawflies. The sawflies have thicker waists, and their larvae, which can be pests, can be distinguished from caterpillars by the legs all down their bodies. Braconid wasps are mostly parasitoids, as are the Chalcid wasps, which means they kill their hosts. They are very small, but you sometimes see their eggs covering the host’s body, or the aphid mummies they leave behind. An insect parasitized by these wasps, even if still alive and munching, should be left alive. Paper wasps are caterpillar predators, and sweat bees are helpful pollinators.
We didn’t talk too much about bees or ants. We’re all familiar with honey bees, but it would have been interesting to hear more about our native bees, especially in light of colony collapse syndrome.
Moth and butterfly larvae are phytophagous, and some are major agricultural pests, so if you want a butterfly garden, it’s best to be tolerant of leaf damage. Most adult forms consume only liquids.
Flies are the most diverse here in the northeast. They have 1 pair of wings, which is a handy identifier, as some look almost like wasps. Houseflies have their role in the ecosystem, but they are troublesome disease carriers for humans.Horseflies have to cut a painful hole in you to get at the blood. Like many insect blood-suckers and stingers, only the females are blood-thirsty. However, hoverflies, which look like bees, have larvae that eat decaying matter or other insects.
After lunch, and some liberal snacking at the ample buffet, we broke into groups to discuss educational and outreach strategies. Seven teams brainstormed on what strategies we could recommend that would attract beneficial insects to gardens, then we chose our favorites and shared them with the room. Our group agreed on some major points that should be emphasized:
1) First and foremost was Diversity Diversity Diversity. Insects have different needs at different points in their life cycles,and in different seasons, all interacting with each other, animals and plants.
2) Provide habitat-leave some rocks and woody debris in the garden to encourage ground beetles. Mulch. Install plants in the parsley or carrot family and the aster, sunflower or daisy family. Vary bloom times, heights and leaf types-insects use all the plant parts at different times.
3) Reduce or eliminate pesticide use. If you removed all the phytophages from your garden, you would soon lose all the beneficials as well. When new pests arrive (and they will!), populations can explode. Additionally, plants themselves can react to limited herbivory by increasing growth
4) Use companion planting to promote plant health and repel or entrap insect pests. Avoid planting in monocultures.
5) Tolerate damage. Sometimes a problem just isn’t that big of a problem. Plants can handle some natural leaf loss, even some agricultural plants, which can still produce a full crop. Unblemished perfection comes with a high chemical price.
6) What about purchasing beneficials and releasing them in your garden? While this can work in the closed system of a greenhouse, it’s generally a waste of money in the outdoors. Lady beetles, for one, might just fly off, or hang around just long enough to reduce the pest population, never to return. It’s better to let them establish naturally by providing good habitat. Their populations will rise and fall with that of the pests.
7) We can educate about and identify insects in our communities, which led us to a second round of team discussions…
REACHING BEYOND YOUR GARDEN
How can you communicate the CCE message about garden insects to raise awareness and change behavior?
Using the same brainstorming technique, we listed strategies that are already being used in various counties. There were a lot of interesting ideas, so when Lori picked up the sheets and said she would be compiling them, I stopped taking notes! Off the top of my head: various CCE’s have a community garden presence, teach vegetable gardening in containers at food kitchens, maintain cooperative extension demonstration gardens,work with school children, or have contact points like our own GrowLine. There were many more, so I looking forward to having my memory refreshed.
After a short break, we got to the hands on part, usually a gardeners favorite, but in this case we had a lot of abstainers. Why collect actual insects? Why collect leaves, or pressed flowers? Because sometimes a version of the actual thing you are trying to identify is more instructive than pictures or photos. Insect collections, like herbariums, can last for many years, and preserve a record of living things for the future. Each county was given a fine collecting box with a poster of common insects that could be attached to the bottom. What a great visual aide and kid-attractor this could be!
First we watched a video of Jason exhibiting exemplary hand eye coordination,using steel pins, tiny tags and forceps. You’ll need the pins (Jason uses special stainless steel insect pins in sizes 1&3), some foam to pin the insects to, stiff paper for identification notes, a storage box that seals tight (to keep out the living insects), and some dead insects. Some of you may remember dead bugs in smelly, dangerous chemicals. Instead, we were told to put them in the freezer in jars. After taking them out of the freezer, you may want to let them warm up a bit, and if they are alive, put them back in. (The whole thing is creepy enough without adding torture to the mix). Some of us already have fridges full of bags of dirt with stratified seeds, dead birds awaiting burial and who knows what else hanging around in there, anyway. If you need to store them outside the freezer, use 70% ethanol, or even water. Mainly, don’t let them dry out before you pin them.
Set the insect on a piece of foam that will push it as high as you want it on the pin. Use a slow, steady pressure.Where to insert the pin can vary. Pin hard-shelled beetles forward of their wings and to the side. Smaller insects will need thinner pins. Very small insects can be glued just under the body on the right side to the end of a cardboard “point”, and the point pinned. Soft bodied insects should not be pinned, for obvious reasons. Then note down the name, location and date on a tiny rectangle of paper, set it on the foam, and push it to a bit below your pinned insect. To standardize the height of the insect and its note on the pin, Jason used a stepped platform of foam.
Finally we were allowed (encouraged?persuaded?challenged?) to do some practice pinning and identifying with jars of random insects collected in sieve net. Tompkins County didn’t get much identifying done, but we pinned courageously, and were rewarded with some professionally pinned specimens to take home.
All in all, a very educational and inspiring day.
Cornell Insect Diagnostic Lab
-Samples identified for $25.00-sometimes they can identify from a photo. Most common answer to questions? It’s not an insect…
Good guide books for insects:
The Peterson Guide