Thursday, June 23, 2016

Widow Skimmer

Widow Skimmers (Libellula luctuosa) are one of the most common dragonflies found in Missouri. They occur most everywhere in the United States with exception to the highest points of the Rocky Mountains.

Like all dragonflies they begin their life in water as nymphs or naiads, feeding on aquatic insects and tiny minnows. They will emerge from the water and shed their skin in their final instar or molt to their adult form. Adult females vary somewhat in color from adult males. Females look very much like immature males and have yellow stripes on either side of their abdomen and a yellow stripe down the center of their thorax. Adult males eventually lose the yellow stripes on the abdomen and they become a powdery blue. They are medium to large sized dragonflies with a wingspan up to 3 inches.

The species name of luctuosa translates into sorrowful or mournful, and is most likely due to the appearance of being draped with a mourning cloak across the wings. In most species of dragonflies the male will remain with the female, guarding her, as she lays eggs in the water. In this species however the female is "widowed" as the male leaves the female to her own devices to lay eggs without his protection. This activity could also be where they get their common name of Widow Skimmer.

Males are territorial and will fight off other males for the attention and right to mate with nearby females. They will even chase away males of other species which are no direct competition for them. This seems like wasted energy to me, but when in doubt chase any possible suitors away which guarantees your right to mate over any other males in the area. Often this species will form male groups in a territory where there is one dominant male that will most likely mate with the females....unless one of the lesser males can pull one over on the dominant male and manage to mate without him being any the wiser.

They are found in areas near slow moving streams, small lakes, ponds and other still waters. We have them in our backyard koi pond as well as a few other species. It is always entertaining to watch them as they chase other males away and compete for females. Like all dragonflies they are carnivores and feed on other insects and they are welcome guests to the backyard as they feed on moths, flies and mosquitoes.

Monday, June 20, 2016

Japanese Beetle

Japanese Beetles (Popillia japonica) in the family Scarabaeidae are native to Japan and made their way into the United States in a shipment of iris bulbs as early as 1912. It wasn't discovered until 1916 inside a nursery in New Jersey. This beetle is known to feed on over 300 varieties of  plants often destroying them. In their native country there are natural predators that feed on them, however in the United States there are no effective natural predators. Birds, frogs and other animals generally won't eat them when they come across them, so they must taste bad. As adults this beetle typically feeds on the green fleshy part of the leaves of plants, leaving only the veins of the leaves. They can skeletonize leaves very quickly and if they occur in large enough numbers they may kill the plants they are feeding on. They may also feed on the fruits present on plants such as grapes, blueberries, etc. In the larval stage, or as grubs, they feed on the roots of various grasses and plants. This beetle in the grub stage, is highly susceptible to a disease called milky spore and scientists have created a biological control agent, Paenibacillus (formerly Bacillus) popilliae. It comes in a powder form that is applied to lawns, but may take several years of application before it adequately controls the population of beetles present on your property. A wasp in the genus Tiphia and a fly in the genus Istocheta have both been proven as effective bio-control, as they will parasitize the beetle. Certain plants are known to repel them such as chives, catnip, and garlic, but with limited success in helping protect plants adjacent to them from the onslaught of these beetles. The estimated damage to turf and ornamentals each year is $450 million, that isn't counting the damage to row crops, forage or trees.

These beetles are rather bumbling in their flight pattern and rarely fly too far in search of food, but they are capable of flying up to a mile for adequate food sources if need be. They give off a pheromone as they feed which attracts additional beetles in the area and results in large aggregations of these beetles all feeding on your prize roses or other plants. When disturbed they will drop off the plant to the ground to avoid being captured by a predator. 

These beetles are tiny at 15mm (approximately 3/8 of an inch) in length with shiny green head, thorax and midline between the wings. Wings are iridescent and may appear brownish, amber, purple or greenish. At the end of the abdomen is a series of white tufts of hair that is a distinctive characteristic of this beetle.
The one pictured here came into work attached to a guests purse. When she picked her purse up off the counter, the beetle was resting on the counter. My coworker captured it and I photographed it before adding it to my insect collection.

Image from:
Adults emerge from the ground in late spring and mating takes place soon after emergence. Once mated the females will burrow 2 to 3 inches into the ground to lay their eggs. She may lay up to 60 eggs in her lifetime and once the eggs hatch (in about 10 to 14 days) the young grubs will live underground feeding on roots for 10 months before emerging the following spring and beginning the cycle all over again.

While these are attractive beetles, they should not be tolerated in your garden, yard or agricultural area. The amount of damage they cause is significant enough to create millions of dollars in loss each year to the turf, and agricultural industries alone. Traps are one way advertised to control these beetles, but all indications point to these traps not being effective as the beetles often land on the outside of the trap and very few end up IN the trap. These traps also use pheromones to attract the beetles which can be counterproductive to eliminating the beetles from your area, and may in fact encourage MORE beetles. If your beetle population is small enough you may lay a drop cloth on the ground below the plants and in the morning shake your plants causing the beetles to fall onto the drop cloth where  you can roll them up and destroy them naturally. You can also put a pan of soapy water below your plants and knock them into that. You may also chose to apply insecticides which are  approved for killing them, but be aware these insecticides may also harm beneficial insects such as honey bees.

Wednesday, June 1, 2016

American House Spider

This oddly shaped, extremely bulbous spider is a house spider (Parasteatoda tepidariorum). I discovered her on the back of my house resting in the middle of a messy web she had created. I placed her on a rock to photograph her and discovered that she was a contrary specimen to capture an image of. She NEVER stopped moving!!! 

I had never seen a spider like her and submitted an image to Eric Eaton of Bug Eric to ID and within seconds he was able to supply me with a name for this spider. I found the name of "House Spider" to be rather dull and boring for such a stunningly gorgeous spider. He told me they are highly variable in coloration, and I must have one of the above average specimens in the looks department. 

Even though this is the first time I have encountered this particular spider (at least as far as I can recall), they are considered one of the most common spiders within the United States. They typically build their webs near human structures where they provide excellent pest control of many insects considered pests by humans, including wasps, cockroaches, ants, flies and mosquitoes. They are even known to try and capture grasshoppers and other larger prey by casting a line of silk at them...rather like spider-fishing. Some specimens will leave flies or other delicacies within the web to lure tiny juvenile skinks into the web so they can feed on a much larger meal. Once the web is full of discarded carcasses they will clean house by dropping the dead bodies to the ground. This keeps things tidy and allows them to keep using the same web without having to build a new one. 

They somewhat resemble black widows, at least in body shape. Unlike widows, which have toxic venom that poses a potential medical threat to humans, these spiders lack venom of any medical significance to humans. Because they reside near humans structures they are somewhat used to human activity and are not bothered by constant human motion. They aren't even particularly defensive, as evidenced by the this one sitting on my finger. She never reared up or even attempted to bite. That doesn't mean they cannot or will not bite, it just means they prefer not to. If they should bite as a result of being smashed or hurt it is no more painful than a bee sting and may cause some itching or slight swelling at the bite sight. if you are sensitive or hyper allergic to bee venom, then the venom from this spider may be of medical significance. They will usually retreat behind a nearby secluded area close to the web if too terribly disturbed. They may also drop from a line of silk and attempt to escape. Their marbled coloring is drab brown mixed with various shades of tan, gray and black which gives them excellent camouflage and they often blend into their surroundings and may go unnoticed by humans. They may also play dead as a last resort if being harassed too much. 

Females are tolerant of males hanging out in their web and you will often find males and females together. Females will build webs within close proximity to each other....but if they happen to encounter each other they will fight. 
After mating, the female may produce 15 or more egg sacs, each containing up to 400 eggs. The spiderlings will remain within the web near the female for awhile before dispersing into the environment. There is a species of assassin bug that feeds exclusively on the spiderlings of this species, so no worries of 1,000's of these spiders surviving in any given location. There are also a couple of spider species that feed on house spiders. 

This spider is often mistaken for brown widows, as their coloring is similar, but they lack the orange hourglass on the underside of the abdomen like the widow. 

MEANING of Scientific NAME
As reported by: 
 U.S. Spiders

The genus name is a combination of the Greek prefix para-, meaning “beside, near” and the genus Steatoda. Prefixes like that are sometimes added to existing genus names in order to form new names for related genera. The name Steatoda literally means “tallowy” in Greek, but it’s assumed that Carl Sundevall was going for something more like “rotund.” The specific epithet, tepidariorum, is a Latin combination that we believe means something like “from the greenhouse (from the warm house)” or “warm area.” C. L. Koch first noticed this species was common in greenhouses at the botanical garden of the University of Erlangen in Germany, so that must be why he chose that name.