Thursday, October 16, 2014

Dotted Wolf Spider

This beautiful pin-striped spider is a Dotted Wolf Spider (Rabidosa punctulata formerly Lycosa punctulata). There are over 2300 species of wolf spiders Worldwide, making them one of the most common spiders in the World. This species is found throughout most of the United States. Autumn is the best time to find spiders as they have reached their adult size and are much more visible. Rest assured they were always present, just not easily seen in their juvenile state. Wolf spiders are some of the most easily recognized spiders in the Missouri. They are almost always large and often furry looking. Which often results in them being mistaken for tarantulas. While we do have tarantulas in Missouri, they only occur in the southern portion of the state. The Missouri River seems to be a barrier for them and they are not found in the northern part of our state.

        (Missouri Tarantula)                                                                        (Wolf Spider)

Wolf spiders however are found all over Missouri; there are five species of wolf spiders within the genus Rabidosa in North America. Dotted wolf spiders are not especially furry-looking like many other wolf spiders tend to be, but they are distinctive in other ways.

(Wolf spider in the genus Tigrosa carrying her babies)

                                                      (Wolf Spider that may be Hogna frondicola)

Dotted Wolf Spiders have bold stripes and a light golden color that sets them apart from most wolf spiders in other genus'. This also makes them rather dashing looking. They also have a series of spots or "dots" on the underside of their abdomen, if you can manage to see them.

Spiders differ from insects in some very obvious ways, insects have 3 body parts (Head, thorax and abdomen) whereas spiders have two body parts (cephalothorax (head and thorax combined into one part, and the abdomen). Insects posses 6 legs and spiders 8. All spiders posses venom and only a few insects do, all spiders can spin silk, only a few insects do. Spiders are meat eaters and do not feed on vegetation. Insects run the gambit of food preferences.

Spiders have unique eyes; most possess 8 eyes with a few exceptions like brown recluses which possess 6 eyes. Most spiders have poor eyesight, but spiders like wolf spiders have exceptional eyesight for their size. Wolf spiders are night time hunters and rely more heavily on their eyesight than do other spiders which rely more on their sensitive sense of touch (in their legs).
8-eyed spiders possess two direct sighted eyes, that are usually dark in color and very visible to the human eye, as pictured here (above right). The smaller, or indirect eyes are not as easily seen by us. These eyes usually have a layer of light reflecting crystals. This reflective quality allows them to see better in low light situations, which is a necessity  if you are a night hunter. Because of the reflective quality of their eyes they will glow when you shine a flashlight on them. This is a fun activity to do with your children. Grab a flashlight and head outside and let the kids shine the light in the grass and look for the "glowing eyes." It will amaze you to see just how many spiders are hunting in your yard.

Wolf spiders produce silk but do not use it to spin webs like orb weavers and many other spiders do. Instead the silk is used to spin egg sacs, to protect spiderlings and to capture food to save for later use. When she forms her egg sac she will carry it with her attached to the tip of her abdomen. When the spiderlings are ready to emerge from the egg sac it will change from a shiny bright white to a dark dirty brown.

 (Wolf spider in genus Tigrosa guarding her egg sac from a large predator....ME)

Then they will climb onto their mothers abdomen and ride around with her for awhile. She guards them temporarily until they are ready to be on their own. Usually a few weeks or so , but there are records of some spiderlings staying on their mothers back for up to 6 months. It is not uncommon to see a female traveling with her brood on her backside late in the summer or early fall. This burden may consist of 50 or more babies. Life span for these spiders is two years or so

Their habitat is typically woodlands, cotton fields and other croplands, old buildings, and grasslands. They may also be found near ponds or in old rodent burrows. Look for them near garbage piles, rock piles, log piles, or within holes in the ground. It is reported that wolf spiders can act aggressively towards humans. I really do not like the term aggression when describing an animals reaction to humans. I prefer defensive. Animals, be it a mammal, reptile or insect will defend itself. Often this defense involves a bite, and many fear a bite from one of these spiders, and it is reported to be painful. They do possess venom, as do all spiders, but the venom is not harmful to humans. It is designed to subdue and liquify their prey. The one photographed here did not exhibit any "aggressive" behavior towards me and I was able to coax her onto my hand for a photo. I handled her in a gentle manner and tried to appear as non-threatening as I could.

Wolf spiders are excellent hunters and typically rely on ambush techniques to capture a wide variety of small insects, including crickets, flies, ants, locusts, and other spiders. They may also run down prey. They help control insect populations, which makes them beneficial to humans. While they are excellent predators, they are often the prey. Small mammals, reptiles, amphibians and other spiders all feed on wolf spiders. There are even a group of wasps called spiders hunters that prey on spiders, especially wolf spiders, and uses them to feed their offspring.  In August I photographed a spider hunter capturing a rabid wolf spider. If you want to read about these amazing wasps the link is Spider Hunter.

                  (Spider wasp dragging a rabid wolf spider to her burrow to lay eggs on the paralyzed body)

 For another great article on this species visit my friend Eric Eaton's blog and read what he has to say about this species.....Bug Eric

Thursday, October 9, 2014

Spider Hunter

Spider Wasps in the family Pompilidae are a cosmopolitan group of wasp with somewhere around 5,000 known species and subspecies Worldwide. As their name would suggest they hunt spiders. There is even a subfamily called Ceropalinae that are known to cannibalize their own kind.

While at Squaw Creek awhile back I saw something small, quick and moving erratically across the road in front of me. This begged to be investigated, so I pulled the car over and found this largish wasp dragging a paralyzed spider from one side of the road to other. I couldn't help but feel somewhat sorry for this poor spider. He was stung, paralyzed, drug across the ground, then across the asphalt and was destined to be a meal for a hungry wasp grub. It is highly doubtful that the spider has any cognitive thought, and that is certainly a good thing. To be aware of your paralytic situation and impending doom at the mouth of a hungry wasp baby and not be able to do a darn thing about it would be the stuff of nightmares.

My presence was casting shadows over the wasp and causing her some pause and she would temporarily leave her prey and wander away. A few minutes later she would return and drag the spider a few feet more and then in a very nervous manner she would depart again. This went on for quite some time and it took her more than 15 minutes to finally reach the other side of the road with her quarry. The spider was quite a bit larger than she was, so the fact that she could maneuver this spider at all is a feat in and of itself. The species of spider is a type of wolf spider called a Rabid Wold Spider (Rabidosa rabida). This particular spider would be very defensive and I imagine not an easy adversary to subdue. I would have loved to see her initial interaction when she discovered the spider and made the decision to use it as food for her offspring. I'm sure it would have been a sight to see.

In most cases the wasp will have dug a burrow prior to hunting for a spider to provision it with. Occasionally though she will dig the burrow after finding her prey. Once she has maneuvered the spider into the burrow she will lay an egg on the abdomen of the spider and then close up the burrow entrance to protect her offspring from predators. When the egg hatches the wasp grub will feed on the paralyzed spider. They will leave the vital organs of the spider until right before they are ready to pupate, this way the spider does not perish before the wasp larvae is done growing. Once the wasp larvae has reached its full size it will form a silken cocoon and pupate. It will emerge the following spring. The size of the spider can determine the sex of her offspring. Larger prey generally produces larger reproductive females. From the size of this wolf spider I think it was destined to feed a female wasp grub.

Spider hunters are solitary wasps and therefore calmer and gentler by nature. They are only prone to sting if mishandled or mistreated. Colony nesting wasps such as hornets or yellow jackets on the other hand tend to be more defensive and more easily provoked. They are guarding nests, queens, offspring and food stores. With so much to defend they need to be on their guard. Whereas solitary nesters like spider hunters are not guarding anything. Once the eggs are laid the offspring are on their own and survival is all up to luck.

Wednesday, October 8, 2014

Imperial Moth

Imperial Moths (Eacles imperialis) in the family Saturniidae are large silk moths commonly found in forested areas throughout Missouri. They are also often found in suburban areas, especially near lights at night. The biggest one I ever found was at a gas station/convenient mart on the outskirts of St. Joseph.
Their range includes most of the Eastern United States from Nebraska to Maine. There are some reports that they are declining at an alarming rate in the northeastern part of their range. The population decline in these locations could and probably is due to habitat loss. Throughout the rest of their range their numbers are secure to abundant. The adults are large with wingspans up to 5.5 inches and are yellow with variable lavender spots. Males are smaller than females.

These large moths do not feed as adults, instead they get all the nutrition they need as caterpillars. If you've never seen one of these in their larval form, it is truly impressive. When hatched they are barely visible and possess an incredible appetite.

 They feed voraciously and reach lengths up to 3 or 4 inches when ready to pupate. They manage this in the span of several weeks.  It has been said that if a human baby gained weight like a caterpillar, they would weigh as much as a hippo in a single weekend. They feed on a wide variety of tree species like oak, hickory, walnut, pine, maple (including box elder), Norway spruce, sassafras, sweet gum and many others.

Moths are covered in furry scales that protect them from cooler nighttime temperatures. These large moths take it to a whole new level with what appears to be a winter-weight coat, complete with scarf and leg warmers. After midnight the females will begin signalling for males by emitting a pheromone. The males are capable of "smelling" the females from distances of more than a mile. He uses his large, feathery antennae to home in on her scent. Females will lay eggs one at a time, or up to 2 to 5 on the leaves of host plants. Eggs hatch in a couple of weeks. When ready to pupate they will move to the base of the host tree and burrow into the ground to pupate for the winter.

Naturalist Gene Stratton Porter wrote about the Imperial Moth in her novel "A Girl of the Limberlost" It was a prominent character in the plot development of the novel. She had a life long love of silk moths and shared her passion for their beauty in the book Moths of the Limberlost.

Monday, October 6, 2014

Differential Grasshoppers

Differential Grasshoppers (Melanoplus differentialis) are probably one of the most common of all the grasshoppers in Missouri. They have a distinguishing herringbone pattern on their hind legs, and are various shades of olive green with yellowish hind legs. They will range in size from 1 1/2 - 2 1/2 inches.

They are found in a wide variety of habitats, including meadows, tall grassy areas, backyards, gardens, open fields and along stream sides. The nymphs and adults both feed on various grasses and crops, including corn, soybeans, alfalfa, cotton, vegetables, fruit trees, and other small grains.

These grasshoppers have many predators, which include birds, toads, frogs, raccoons, opossums, turtles, bats, praying mantids, red fox, dragonflies, yellow jackets, fish, shrews, lizards, chipmunks, squirrels, spiders, centipedes, crickets, beetles, and the neighborhood cat. The larvae of the Blister Beetles use the eggs of grasshoppers as their primary food source.

Mating occurs in late summer and early fall. The females will press long eggs masses into the ground, near weeds. She may lay up to 8 egg masses each containing about 25 eggs. The eggs will overwinter and hatch the following spring. The newly born nymphs look very much like the adults. They will shed their exoskeleton (outer skeletal skin) several times over a course of two months before reaching adult size (picture 3). It is common to see these shed skins hanging from branches or grasses. Looking very much like they were scared right out of their skin and left it behind

Sometime in the fall when the temperatures begin to drop, and the first freeze hits, the adults will perish. Often time frozen right to the spot that they had been clinging to. It is almost eerie to come across one of these dead grasshoppers, it is almost like some mass weapon of destruction came through and freeze-dried them. (Below)

Sunday, October 5, 2014

Obscure Birdwing Grasshopper

Obscure Bird-Wing Grasshoppers (Schistocerca obscura) are extremely large grasshoppers that can be found from the Northeastern United States westward to Arizona. They are very common in the Midwestern states. Females are larger than males and according to they may reach 65 mm or a little over 2 1/2 inches. I swear that this specimen was much larger than 2 1/2 inches, it was easily 3 inches or more in length. Absolutely the largest grasshopper I've ever seen. There were several other birdwings in the area, and all we more typically sized for the species. This one was like the Arnold Schwarzenegger of grasshoppers. He had probably gorged himself on the multitude of tomatoes and other garden veggies that were left over from our summer garden. I tried numerous times to catch him, but he proved to fast and hoppy for me to succeed. I wanted to get a measurement on him so badly. 

Fields and open woodlands are their usual habitats, but I find them frequently by the garden or in flower beds. I would assume like any grasshopper they go where the food is. They can on occasion become a pest to garden plants or prized flowers, but generally speaking they pose no significant threat and eat on wild grasses, forbes and other plants. 

Grasshoppers seem to be prolific this year and are everywhere in large numbers. They are beneficial to wildlife who will gorge on them in autumn. It is not uncommon to find the craw of a turkey full of grasshoppers, especially young turkeys who seem to favor the tasty little buggers. Other animals such as bobcats, foxes, mice, frogs and all sorts of birds find the bounty to their liking as well. What a great way to find protein without a lot of effort.

These grasshoppers can be difficult to identify as there are other similar birdwing species. This one is a vibrant green color with a gorgeous yellow stripe down the back. The wings are dark brown and the antennae are also yellow. In my area it tends to be the most common birdwing, therefore it would be hard to mistake for anything else, as there is very little to compare it to. However, if you live in areas where other birdwings are common, it may prove difficult to ID.

Mating takes place in the fall and females use their ovipositor to deposit eggs under the soil. The eggs overwinter and hatch in the spring. The nymphs are born looking very much like the adults, minus wings and adult coloring. They will molt up to 9 times before reaching adult size in mid to late summer. Adults die over winter so all grasshoppers spotted are that current years hatch.