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Posts tagged “Arthropods

Ant Mandibles

Ants go through complete metamorphosis, passing through four stages (egg, larva, pupa, adult). Like honeybees, there are queens, female workers and male drones in an ant colony. The female worker ants have a series of “jobs” that they perform in a certain order. A young worker spends the first few days of its life caring for the queen and young. After that she maintains the nest and eventually forages for food. Like most insects, ants lack grasping forelegs and compensate for this by using their mandibles as “hands.” When the nest is disturbed, workers rush to rescue the eggs, larvae (depicted in photograph) and pupae by clasping them in their mandibles and transporting them to safety. They also use their mandibles to carry food, construct nests, and for defense.


Leafcutter Bee Cell Leaf Sections

At the risk of boring readers, I wanted to include one final Leafcutter Bee post, showing the two basic shapes that these bees chew out of leaves in order to make their incubator/nursery cells.  There are oblong pieces, roughly an inch long, as well as perfectly round, ¼-inch diameter pieces.  Each cell consists of several layers of oblong pieces rolled lengthwise which are sealed at one end with a round piece of leaf.  The round end pieces appear to be glued into place (perhaps with the pollen/nectar mixture?) at one end of the cell, leaving the opposite end open.  The cells are arranged end-to-end, with the open end of the cell placed against the sealed end of the next cell.  Together they form a nest that is somewhat cigar-shaped and is typically located a few inches down in the soil, or in a cavity.


Broad-necked Root Borer

This impressive egg-laden, 2-inch long female Broad-necked Root Borer (Prionus laticollis) was attempting to lay her eggs when I discovered her. She repeatedly extended and retracted her ovipositor (pointed, egg-laying structure at tip of abdomen) in an attempt to probe the packed dirt in my driveway, but finally moved on to softer soil. Female Broad-necked Root Borers insert clumps of eggs into the ground. When the eggs hatch, the larvae tunnel downward to feed on the roots of a variety of shrubs and trees. In the spring they pupate, and adults, such as this female, emerge. This whole life cycle is thought to take three years.


Wolf Spider Mother and Spiderlings

Two common spiders that we often see carrying their egg sacs are the wolf spider and the nursery web spider. Wolf spiders attach their egg sacs to their spinnerets, whereas nursery web spiders carry them with their mouthparts. When nursery web spiders are about to hatch, the mother puts her egg sac into a silk tent she has spun, and they live there for a week or so. When a wolf spider’s spiderlings emerge from their egg sac, they climb up onto their mother’s abdomen and cling to it while their mother continues to hunt for food. After about a week, when partially grown, the spiderlings disperse, either by ballooning through the air on silk strands or simply by scurrying off along the ground.


Mourning Cloak Butterflies

With the warm temperatures this week, mourning cloak butterflies have been seen gliding through the leafless woods.  Like eastern commas, question marks and red admirals, mourning cloaks overwinter as adults.  They resemble dead leaves so much that from a distance the entire insect seems to disappear.  Up close you can see the velvety texture of the wing scales, said to resemble the clothing mourners used to wear; hence, their common name. Mourning cloaks live up to ten months — an impressive life span for a butterfly.  As they age, the yellow border of their wings fades to an off-white.


Snow Flea Mystery Appendage

Snow fleas, a species of springtail, are neither fleas nor insects (though, like insects, they are arthropods). During most of the year they live in the soil and leaf litter, consuming fungi and decaying vegetation.  On warm winter days they appear on the surface of the snow, and are often described as “pepper on snow” due to their black color and tiny size (1 – 2 millimeters long).  Although they lack wings, they have two tail-like spring projections, or furcula, which are held like a spring against the bottom of the abdomen by a kind of latch.  When the snow flea wants to move, the furcula springs downward, catapulting the snowflea as far as 100 times its body length.  I observed something recently which I have neither heard nor read about, and that is a four-pronged pinkish appendage which emerges from the tip of the snowflea’s abdomen just before it flings itself to another spot.  At all other times, this structure is withdrawn into the abdomen and is not visible.  Photographing this structure during the split second it is extended was quite the challenge, and I would love to hear from anyone who might know its function.  NEWS FLASH –  mystery solved by Charley Eiseman, author of TRACKS & SIGN OF INSECTS: Those three (not four) structures are anal sacs.  According to Frans Janssens,  “just before hopping in the air, three sticky vesicles are everted from the anus: they serve as a kind of sticky safety bag that prevents the specimen [from] bouncing around when it lands after the jump.”  ONE LAST UPDATE:  from Dr. Ken Christiansen, Professor Emeritus of Grinnel College, AKA Dr. Snowflea, who reports that these anal sacs are only found on species within the Hypogastrura genus, and that their function is unknown.


Millipede Mystery

This morning I discovered the exoskeletons of nine millipedes clumped together at the top of a rotting stump.  They were covered with slug slime, with said slug still at the scene. Presumably its stomach was full of millipede innards.  If anyone can explain this phenomenon to me, I would be most grateful!