Flying in the winter

I caught this insect out of the corner of my eye the other day while I was on a hike.

This is a Winter Crane Fly (Diptera: Trichoceridae). It was sitting on the snow when I took the picture, but it had been flying moments before even though the air temperature was about 35℉  (1.5℃).

Winter crane flies are active in the fall and early spring, when temperatures are too cool for most other insects to fly. They are able to fly on cold winter days because they have a special enzyme system that allows their wing muscles to function at low temperatures. 
Insects have a number of different adaptations that allow them to survive at very cold temperatures. This is especially important in parts of the world where the temperature drops below freezing for several months of the year. Most insects are able to keep their blood from freezing with the help of special compounds called cryoprotectants. Cryoprotectants work like the antifreeze in a car by lowering the freezing point of the blood. Thanks to the cryoprotectants in its blood, the winter crane fly in this picture survived temperatures as low as 18℉ (-8℃) the night before. 
Insects can also allow their bodies to freeze completely by controlling where and when ice crystals form with the help of ice nucleating proteins. Ice nucleating proteins cause ice crystals to form outside of the insects' cells rather than inside of them. Ice crystals forming inside of the cells would destroy them and kill the insect. 
As amazing as these adaptations are, they do not happen instantly. The insects need  time to adjust their bodies and prepare for the cold weather, so if you catch an insect in the summertime and put it in your freezer overnight it will probably die.
If you're interested in reading more about this topic, check out the Wikipedia article on insect winter ecology or this book chapter on freeze tolerant animals.

Flying scorpion? No.

I'm sure this has happened to you. You're walking along in the woods and you see something black and wispy go by out of the corner of your eye. You naturally think, "Oh, there goes a damselfly, a mayfly, or a crane fly," but when it lands on a nearby plant you realize that its something much more sinister. That happened to me in late September this year and all I could get was this fuzzy photo before it flew away.

Fortunately, I was gardening a few weeks later, in October, and my friend found another one. This time it was not flying because it was probably too cold outside, so I was able to get in close for a really nice picture.

These are pelecinid wasps (Hymenoptera: Pelecinidae) in the genus Pelecinus and they are actually not that sinister...unless you are a june beetle (Coleoptera: Scarabaeidae Phyllophaga). That long "tail" is really just their abdomen, which all insects have. Their abdomen is longer and skinnier than most because they use it to dig into the soil in search of june beetle larvae (AKA white grubs). Once they find a white grub, they lay an egg on it. Eventually the egg hatches and the wasp larva attacks and kills the grub, feeding off of its corpse until it matures.  Then the wasp larva will pupate right there in the soil and emerge next summer as an adult wasp. 

Because of their long curved abdomen, pelecinids do sort of resemble scorpions which has led some people to call them scorpionflies. However, that name belongs to another group of insects in the order Mecoptera, the true scorpionflies. Of course, neither are flies (order Diptera) or scorpions, and scorpions are not even insects. Scorpions are arachnids (like spiders, harvestmen, and mites). Whew, glad we cleared that up. 

Regardless of how scientists classify them, pelecinid wasps attack and kill white grubs, which can be a nuisance to gardeners and homeowners, so we here at Crunchy Segments classify them as beneficial insects. Keep up the good work pelecinids!

Wolf Beetles

This is a beetle of the family Lycidae (Coleoptera). 

The official common name for this family is net-winged beetles but I prefer to call them wolf beetles. The family name Lycidae comes from the Greek lykos, which means wolf. They were given this name because some species have an elongated face that resembles a snout and gives them a somewhat wolf-like appearance. However, the name net-winged beetles is probably more appropriate since the majority of species do not possess a snout, and the distinctive raised ridges on their elytra help distinguish them from other beetle families that occur in the same habitats and have similar coloration.

For example, soldier beetles (Coleoptera: Cantharidae, right)
and fireflies (Coleoptera: Lampyridae, below) are often found on foliage or flowers during the daytime. Many of these beetles also are brightly colored with alternating patterns of black and yellow or orange. This type of coloration is thought to warn predators that they are distasteful or poisonous. 

Aphids, what the heck are aphids?

I have written about aphids before, but never dedicated a post to them. Aphids are in the insect order Hemiptera. Aphids feed almost exclusively on plants so they fall solidly under the category of pests in the garden. 

Annoying as they may be to gardeners and farmers, aphids are very interesting creatures. 

Aphids often live in colonies where the mother or fundatrix gives live birth to many genetically identical offspring. Most of the time they are just feeding on the phloem (AKA sap) of plants, which is where they get most of their nutrients. 

Individual aphids are fairly sedentary creatures, but every once in a while, the colony produces winged aphids that go off in search of new food plants. Ants will also sometimes carry aphids to new plants (e.g. see this article about the corn root aphid). Ants and aphids sometimes form a symbiotic relationship where the ants protect the aphids from predators and the aphids provide the ants with honeydew. The aphids secrete honeydew as a byproduct of their feeding on the carbohydrate rich but nutrient poor plant sap. For the ants, the honeydew is an important source of carbohydrates (sugars). 

If you have ants tending aphid on a plant in your garden, one solution is to create a sticky barrier around the stem of the plant. This will prevent the ants from protecting the aphids, and the aphids' natural enemies will be able to attack them. Aphids have many natural enemies, including lacewing larvae, lady beetles, and parasitoid wasps.

Flying Tigers

This seems to be the summer of predatory flies. I have written about long-legged flies, robber flies, and now tiger flies (AKA hunter flies). Tiger flies are in the family Muscidae, which is the same family as the common house fly and at first glance they are very similar in appearance to a house fly.

If you look closer at this photo though you will see a very important difference.

This tiger fly is eating an insect that it has just caught. Tiger flies sit and wait on vegetation for a potential prey item to fly by. Then they will take off, catch the prey,  and return to the perch to eat it. This is very similar to the predatory behavior of the robber flies that I wrote about a few weeks ago. 

Tiger flies are interesting also because of their apparent tameness. I was able to get very close to this fly with my camera without disturbing it. One researcher has even developed a technique for using these flies to gather insects much like a falconer uses birds of prey to catch game.

Tiger flies can be very helpful to us in the garden, vineyard, and orchard. They are known to eat economic pests such as leafhoppers, whiteflies, and aphids.

Tree crickets are awesome!

This is a tree cricket (Orthoptera: Gryllidae Oecanthus sp.). 

Tree crickets, like all crickets, are closely related to grasshoppers and katydids (see this previous post for some info on how to tell them apart). You may not see tree crickets as often as some other kinds of crickets because they usually blend in with the vegetation that they hang out on. I was lucky enough to find this one on a pink flower. Tree crickets are very interesting but poorly understood insects. Here is a link to a great website created by an amateur entomologist that is very enthusiastic about them. Tree crickets feed on a variety of things from plants to other insects and even fungi. Some species are more predaceous than others, but they are rarely considered pests in the garden.
Tree crickets hear through special membranes on their forelegs.

Hearing is very important for crickets, because they use sound to find their mates. In tree crickets, the male calls females by chirping with his wings. Once, the female locates a male, they engage in some very interesting mating behavior.

Not so cute bug.

I'm pretty sure this is the same species of caterpillar (Lepidoptera: Sphingidae Eumorpha pandorus) that I wrote about in another post last year. The title of that post was, "cute bug?", but I don't think this caterpillar is nearly as cute as the ones that I took photos of last year. This photo is from just a few days ago.

This caterpillar is also much larger and more mature than the bright red one that I saw last year.

Based on the size and shape of this one, I'd say its just about ready to form a chrysalis and pupate. It was munching away on a wild grape vine and frankly could have used a napkin. 

Robber Fly

I caught this robber fly (Diptera: Asilidae) with my camera a few days ago. 

Robber flies are predators of a lot of other insects. They aren't particular about what they eat, if they can catch it they'll eat it. They sit and wait for prey to fly by and then attack them on the wing. 

They kill their prey by injecting them with a toxic saliva. The robber fly's mouthparts fit together to form the proboscis that they use to inject the saliva. Robber flies can be distinguished from other similar flies by the distinctive notch on the top of their heads between the compound eyes. There is a great deal of variation in body shape, size, and color among the species of Asilidae. For example, some robber fly species are excellent mimics of wasps or bees, which helps protect them from predators. Robber fly larvae can be found in the soil or in decaying wood where they feed on the larvae of other insects.
In the garden, robber flies are generally considered beneficial predators of pests. However, they are not picky about diet choices and will sometimes be seen eating other beneficial insects such as honey bees, wasps, spiders, and even other robber flies.

Dance Fly! Dance!

This is a long-legged fly (Diptera:Dolichopodidae), so named because their legs are rather long in proportion to their bodies compared to other flies. 

My friend sent me this picture of one the other day. 

Unfortunately, that one was deceased. 

Long-legged flies are beneficial insects that you have probably seen around your yard or garden this summer. They are predators of insects and other small invertebrates. They are pretty easy to identify since they are shiny green and metallic with very prominent compound eyes and a thinner body than other green metallic flies. You can tell them from green metallic bees by the fact that they only have one pair of wings. I sometimes confuse them with closely related fly family called dance flies (Diptera: Empididae or Hybotidae), because I see them "dancing" on leaves more often than I see "dance flies". Long-legged flies are very fast runners and you may see them scooting quickly around on leaves in search of their tiny prey. Dance flies on the other hand, got their name from the aerial maneuvers that the males perform in mating swarms.

Some members of these fly families have very interesting courtship behavior. For example in some species the male will kill another insect, bundle it up and bring it to a female as a gift. Biologists call this a nuptial gift and if the female accepts it she will often allow the male to mate with her and use the nutrients in the gift to nourish her offspring. Like many insects, they also perform elaborate behaviors that resemble dances during courtship. Here is a video of the courtship behavior of one species that I downloaded from the Dolichopodidae Wikipedia page.

Long-legged flies are one of my favorite insects to see during the summer and I hope that you will enjoy seeing them too!