An online resource based on the award-winning nature guide

Arthropods

Millipedes Meandering

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How do you distinguish a millipede from a centipede – both multi-segmented arthropods that have a lot of legs? Although there are many less obvious differences, centipede bodies are relatively flexible and they have one pair of legs per body segment. Most of a millipede’s segments have two legs, and their tubular body is quite rigid.

Depending on the species, millipedes have between 80 and 750 legs, with most having fewer than 100, but they didn’t start out their lives with this way. When they hatch, millipedes only have three pairs of legs; every time they molt, they add more body segments and legs. When threatened, millipedes quickly coil their body into a spiral, protecting their legs and fragile underbody with their armor-like body plates (tergites).

If you come across a millipede, know that you’re looking at one of the earliest animals to breathe air and make the move from water to land. Pneumodesmus newmani, a fossil found in Scotland, dates back 428 million years and is the oldest fossil specimen with spiracles for breathing air.

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American Dog Ticks Can’t Give You Lyme Disease

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With the plethora of ticks this spring, it is perhaps comforting to know that not every tick you extract from your body has the potential to give you Lyme disease (or the powassan virus or many of the other diseases carried by Blacklegged Ticks (Ixodes scapularis), also known as Deer Ticks).

The American Dog Tick (Dermacentor variabilis) is the most commonly encountered tick in northern New England. It is found predominantly in areas with little or no tree cover, such as grassy fields and scrubland, as well as along walkways and trails. This species of tick feeds on a variety of hosts, ranging in size from mice to deer and humans. Despite the fact that the bacterium that causes Lyme disease has been found in American Dog Ticks, tests prove that the tick can’t transmit the organism to its hosts. Therefore, the American Dog Tick isn’t involved in the spread of Lyme disease. (It does transmit Rocky Mt. Spotted Fever, however, but there are relatively few cases of it in the Northeast.)

The UNH Extension Service has such a succinct description of this tick’s life cycle that I am sharing it here. It is a “three-host tick,” so named because it must find and feed on an animal three times to complete its two- year life cycle…The dog tick begins life as an egg, one of hundreds laid in a mass on the ground by a female tick. The egg hatches into a larva, which has six legs. The larva remains on the ground in leaf litter, or in low vegetation while waiting for a small mammal (usually a rodent) to brush by. It attaches to the animal and feeds for several days. Then it drops off and molts to the nymph stage, which has eight legs. Again it waits for a host (usually a rodent) to brush by. When that happens, the tick attaches and feeds on it for several days. When fully fed it drops off and molts to the adult stage. Adult ticks wait on shrubs or tall grass and attach to larger mammals such as people, deer, or pets. They also take several days to fully engorge (feed). A female fully engorged with a blood meal can be almost the size of a dime, appearing smooth and shiny. Mating takes place on the host, and when fully fed, the females drop off and lay eggs. The life cycle can be as short as three months. (Photo: American Dog Tick, Dermacentor variabilis)

CDC TICK PREVENTION TIPS:

Use repellents that contain 20% or more DEET (N, N-diethyl-m-toluamide) on exposed skin.

Use products that contain permethrin on clothing. Treat clothing and gear, including boots, pants, socks and tents.

Bathe or shower as soon as possible after coming indoors to wash off and more easily find ticks that are crawling on you.

Check yourself, your kids, and your pets for ticks daily, especially after they spend time outdoors in areas where ticks may be found.

Remove attached ticks as soon as possible. The preferred method of removal is to grasp the tick close to the skin with tweezers or fine-tipped forceps and gently pull upward with constant pressure.

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Grasshopper Wings Growing

7-21-16  grasshopper wings 092Grasshoppers experience incomplete metamorphosis, with three life cycle stages – egg, nymph, and adult.  A grasshopper egg hatches into a nymph, which resembles an adult grasshopper, except that it is smaller and lacks wings and reproductive organs.  Because of its hard outer exoskeleton, a growing grasshopper has to shed its skin periodically to accommodate its increased size.  (A larger exoskeleton develops beneath the old, smaller one that is shed.) Grasshopper nymphs molt several times (each stage between molts is referred to as an instar) before they reach their adult size, and with each molt, their “wing buds” get larger.  After the final molt, the wings are inflated and become fully functional.  Wings play an important part in grasshopper courtship, as males “sing” to attract females by rapidly rasping their leg against their forewing, a process called stridulation.

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Darners Laying Eggs

9-1-15 dragonfly laying egg 135Females of different species of dragonfly have different techniques for laying their eggs. Most skimmers, cruisers and clubtails dip the tip of their abdomen to the surface of the water while hovering or flying, and release their eggs. Most darners, such as the Shadow Darner (Aeshna umbrosa) pictured, have a sharp-edged ovipositor with which they slit open a stem or leaf of a plant on or near the water. They then push their egg into the plant tissue exposed by the slit. Because they are stationary during this process, female darners are vulnerable to predation by fish and frogs at this time. A close look at the bottom third of cattail leaves this time of year will tell you whether or not darners are in the vicinity, as the slits they make are very apparent, appearing as thin, tan, 1/2″ vertical lines.

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Hover Fly Mimics Bald-faced Hornet

8-5-15 bald-faced hornet and hover flyAdult hover flies, often referred to as syrphid (family Syrphidae) or flower flies, feed on pollen and nectar, and are often seen hovering at or crawling on flowers. Many have black and yellow bands on their abdomen, and are frequently mistaken for bees. There are certain species of hover flies that mimic stinging wasps, including yellow jackets and bald-faced hornets (see photo). Predators such as birds, ambush bugs, and spiders might think twice about eating an insect that can sting, and hover flies take advantage of this. The process through which this occurs is called Batesian mimicry, and refers to when a harmless species evolves to imitate a harmful species that has the some of the same predators.

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Snowfleas Appearing

snowfleas 049A7533One rarely even thinks about snowfleas (a species of springtail, Hypogastrura nivicola) until snow falls and then starts to melt. This is when these tiny wingless arthropods that catapult themselves through the air with the aid of a fork-like structure, or furcular, seem to magically appear out of nowhere. They actually are present year round, but their dark color makes them visible against the white snow.

The great majority of snowfleas live in soil, feeding on fungi, algae, decaying plant matter and bacteria. They work their way to the surface of the snow, crawling up the trunks of trees, plant stems and side of rocks where an open channel allows their migration. Thousands can be found on melting snow, especially in tracks or other depressions. No-one is absolutely sure of why they exhibit this behavior, though some scientists feel that these migrations are triggered by overcrowding and lack of food. Eventually those that survive on top of the snow make a return trip down into the soil.

Formerly classified as insects, snowfleas are now categorized as hexapods, due to some features they have which insects do not.

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Millipedes Migrating

11-11-14 millipede IMG_8982We don’t often see millipedes because of their preference for secluded, moist sites where they feed on decaying vegetation and other organic matter. Compost piles, heavily mulched shrub or flower beds, rotting logs, or the soil under logs and stones are likely spots to find these arthropods. Millipedes overwinter as adults, and have been seen migrating in the fall, presumably in search of overwintering sites that will provide them with some protection.

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