Category: Insects

The praying mantis refers to a group of insects comprising about 2,400 species around the world.  Most of these animals live in rainforests, but there are eighteen species that live in North America.  The Carolina mantis, Stagmomantis carolina, is the only species native to Illinois and can be found in the southern half of the state.  The most common mantis found in northern Illinois, as well as throughout the U.S., is the Chinese mantis, Tenodera sinensis, originally introduced in the Philadelphia area in the early 1900s to control agricultural pests.

Praying mantises are the only insects that have a unique, flexible joint located between the head and prothorax allowing their heads to turn a full 180 degrees to look straight backwards.  Mantis species have two large compound eyes composed of dozens of ommatidia.  Humans have a simple eye, one ommatidium, that creates 3-dimensional images by comparing light and dark patterns to discern depth.  A mantis detects movement from the many angles of each ommatidium and forms a 3-d image showing direction and distance.  Mantises have only one ear, located on the belly just in front of the hind legs.  They can hear a full range of sound including ultrasounds, but cannot detect frequencies or direction.  Ultrasound detection allows a mantis in flight to avoid potential predators, such as bats, that use ultrasound echolocation to identify prey.

Many animals, especially in tropical rainforests, use heavy vegetation for cover.  The praying mantis is an ambush hunter, stalking prey with slow, stealthy movements or waiting for prey to come close before pouncing and using the sharp spines on its forelegs to grab and hold the prey.  Most mantises are camouflaged with colors and patterns that easily blend in with their native habitat.  Here in Illinois, they are plain, dull colors of green, gray or brown.  The Chinese mantis is one of the best hunters of any mantis species, and it is adept at capturing birds.  In the U.S., their favorite prey is the Ruby-throated hummingbird. 

In late summer, praying mantis males and females mate and females will lay eggs a few weeks later.  Males try to mate with as many females as they can.  However, there is danger for the males during this activity.  Females are larger and may cannibalize the males during mating.  This only happens about 20% of the time, and females gain important amino acids that end up in the eggs and allow the females to produce more eggs than she otherwise would.  In late autumn, females deposit 50 to 200 individual eggs  along a twig or stem, attaching each egg by covering it with a frothy, foam-like substance, that hardens  creating an egg case called an ootheca.  The eggs will remain encased until spring.  The average life span is about a year; adults in the tropics live slightly longer, but adults in temperate zones will die over winter.

Praying mantises eat lots of insects, and they have been imported into many areas to provide pest control for agriculture.  This has not worked very well because mantises are generalists when it comes to prey, eating everything without distinguishing between “good” garden bugs and “bad” garden bugs.  Having several in your garden may result in removing just as many pollinator species as pest species.  Praying mantis can grow up to five inches, but carry no toxins, venom, stingers, or infectious diseases  and are harmless  to humans.  Be on the lookout for the egg cases among the bare branches in your yard this winter and be prepared to observe them hatch in the spring and populate your yard.

Nighttime brings out animals that are nocturnally active or that may simply be more noticeable during night hours.  Rarely seen, but heard widely throughout the night, members of the cricket family, Gryllidae, may call at all hours of the day, or sing only during the night.  Crickets are in the order Orthoptera, distinguished by having two pairs of wings, long, segmented antennae, chewing mouthparts, and the ability to sing by rubbing one body part against another.

There are six groups of crickets found in Illinois encompassing many species.  Field crickets are small, up to an inch long, black or dark red, and live in undergrowth that provides protection from wind and cold.  Found across all of North America, adults and young cannot survive freezing temperatures and whole populations die off in the northern part of their range each year, while southern populations may produce multiple generations.  Eggs are laid singly, in the soil in autumn, and a new generation hatches the following spring.  A second group, house crickets, are not native to North America, and also cannot survive winter.  Imported for many years as fishing bait and pet food, many escape to live and reproduce indoors.  Females emit a chemical repellant to other females that encourage them to start new families elsewhere.

Two additional groups, bush crickets and tree crickets, are common throughout the United States.  Residing in trees, shrubs, and other vegetation, they are excellent singers.  Females, locating a male to mate with by his song, nudge the male to interrupt his singing and they mate.  The female punches a series of pin-like holes in thin bark, filling each with mucus and one egg, then plugs holes with chewed bark.  The pattern of holes can be used to determine the species.  Eggs overwinter under the bark, hatching in spring.  Nymphs grow into adulthood by mid-summer.  The last two groups include mole crickets that are strong flyers, but spend most of their lives underground, and camel crickets with short, wingless, hump-backed bodies.

Crickets, like grasshoppers, have a sharp edge called a scraper on one forewing that rubs against a bumpy ridge, called a file, on the underside of the other forewing.  The song produced can be a chirp or a rapid trilling which is more musical than the grasshopper’s rasp and buzz.  A cricket’s wings are long and tough.  They are generally used for protection and flight, and are always used for singing.  In addition to flight, crickets are jumping insects.  They have three pairs of legs attached to the thorax.  The first two are small, but the hind legs have enlarged, muscular thighs and rigid lower legs, with a knee joint designed to provide the ability to jump long distances.

Cricket songs are directly affected by temperature.  As temperatures decrease, individuals will sing more slowly.  For crickets, the pitch also decreases.  Field crickets sing a series of chirps, and the outside temperature can be calculated from their song by applying Dolbear’s Law, named after A.E. Dolbear, who quantified the formula in 1897.  Take the number of chirps per minute, subtract 40 and divide the result by four.  Add fifty to get the temperature in degrees Fahrenheit, accurate to within one  degree.  Collecting crickets for their songs is a pastime in China and Japan where artisans have created beautifully decorated, hand-crafted cages for the past one thousand years.  Tonight, after dark, take a stroll outside to hear the wonderful chorus in your neighborhood.

Lady beetles, popularly known as ladybugs, are a beloved and diverse group of insects found in many backyard gardens.  Oval to round in shape with a head that is partially covered by the pronotum, the plate covering the thorax, they come in a variety of colors, with or without spots.  Identification is made based on spot shapes and patterns.  There are about 500 species living in the U.S., most of which are predatory, which makes gardeners love them.  Many species have long, slender larvae with dark, spiny bodies that are also predators of garden pests.

Female ladybugs produce upwards of 1000 eggs laid in batches, several times over a period in late spring and early summer.  Eggs hatch in five to eight days, and larvae pupate to adulthood in three to seven weeks.  Their one-year life span takes them through winter hibernation under logs, buildings, and snow drifts, and in many houses.  Gathering in large groups of several hundred to several million, ladybugs can survive up to nine months of cold temperatures,  living off fat reserves.  They over-winter near their food sources and wake in spring when temperatures reach above 55˚F/13˚C. 

Ladybugs live in a variety of habitats, wherever aphids can be found, including forest, meadow, marsh, prairie and backyard gardens.  Feeding on soft-bodied insects, they provide natural pest control, especially in our gardens.  Both adults and larvae can consume several dozen insects daily.  Primary prey include aphids, spider mites, thrips, scale, insect eggs, and small insect larvae.  Ladybugs are also considered important for pest control in agricultural areas.  About 3,000 ladybugs can protect an acre of fruit trees or other crops.

Several non-native species can be found throughout the U.S.  Most have been brought here as part of a  biological control effort, but they can negatively affect native populations by outcompeting them for  food.  Several of these introduced species are now considered to be serious pests,  especially when inadvertently collected along with grapes for wine production, giving the finished product a sour flavor.

In early spring, before aphids hatch, several ladybug species located in the northern U.S. depend on pollen for up to half of their diet.  Providing early-flowering species containing a high pollen load can be very beneficial.  Several plants can be added to your garden that will help fulfill this need for ladybugs and other local pollinators including heather, red-flowering currant, grape hyacinth, and dandelion. 

Ladybugs are considered omens of good luck all over the world.  Four of them were carried into space on one of the shuttle missions to test the effects of zero gravity on insects.  Results indicate they have no trouble capturing their prey without gravity.  They are the official state insect in Delaware, Massachusetts, New Hampshire, Ohio and Tennessee.  Check out your backyard or nearby gardens to see these tiny natural wonders in action.

Grasshoppers, familiar insects of summer, are found all over the world with about 550 species native to North America.  Grasshoppers, crickets, and katydids make up the insect order Orthoptera, characterized by hard, external skeletons, three pairs of jointed legs, three-part bodies, compound eyes and two antennae.  Their mouths are used to shear vegetation and the palps on either side of the mouth are used for feeling and tasting.  Tympanal organs are holes under the wings, at the base and sides of the abdomen and perform the same function as human ears.  They have a leathery upper pair of wings that folds over to cover and protect a lower pair of wings.  The back legs are large and muscular for jumping.

Grasshoppers are one of the many insects that use singing to attract a mate.  The hind legs are used as a “bow”.  A set of peg-like protrusions on the inside of the leg are drawn across a raised vein on the forewing making a rasping sound.  This is called stridulation.  Other species may use crepitation, the ability to make loud snapping noises with their wings while in flight.  Although both males and females are capable singers, singing is all about staking territory and finding a mate, and males tend to be more vociferous.  Grasshoppers are strictly daytime singers and get more vocal as daytime temperatures soar.

In all singing insects, females will begin searching for a place to lay eggs immediately after mating.  Breeding sites require undisturbed soil found in empty lots, roadsides and open fields.  A female will push her ovipositor into the soil and secrete a frothy substance within which the eggs are suspended.  This dries into an inch long plug containing two to a hundred eggs.  Eggs remain underground over winter and hatch in spring.  Nymphs are simply miniature adults, molting through five instar stages while they grow.  Wings and sexual organs develop during this period.  A large number of eggs are lost each year to soil disturbance and weather, especially flood conditions.

Grasshoppers are a type of locust, a group of insects found in swarms that may be harmful to crop production, although this behavior is rare in Illinois.  They are well adapted to urban environments, feeding mostly on a variety of grasses, but they may also eat leafy vegetables, beans, corn and ragweed.  In agricultural fields their favorite foods include alfalfa, corn, barley, and wheat.  A heavy infestation of 16-17 grasshoppers per square yard will consume one ton of leaves per day in a 40 acre field.  Grasshoppers are particularly hard to control because of their great mobility, but, there are natural controls from predators including poultry, birds of prey, spiders and rodents to diseases caused by fungi, protozoa and nematodes.

Observe a grasshopper while it is eating and notice the ragged, serrated edge left along the chewed area versus the smooth-edge cut from a caterpillar.  When molting, they hang upside down from grass or twigs.  The skin splits open along the back and the insect pushes outward to clear its wings and antenna first from the old casing.  When moving through wet soil, hopping leaves two deep impressions from the rear legs with four much lighter impressions from the front toes and sometimes a line down the center where the abdomen may drag.  Nymphs are able to move long distances by walking, while adults can fly miles at elevations of several  hundred feet.  Have some fun watching these interesting insects and their behaviors in your own backyard.

Lightning bugs are fireflies, but fireflies are not flies and lightning bugs are not true bugs.  Fireflies are winged beetles in the Lampyridae family.  The family is known for their ability to produce light from chemical reactions.  There are about 2000 species worldwide, including almost 200 in North America, but only three species can be found in Illinois.

Fireflies use their lights as signals to find mates.  Preferring early summer’s warm and humid evenings, fireflies start to flash as soon as it is dark, and continue for several hours.  Males fly a repetitive pattern in one area, flashing and watching for a return flash from a female lying in wait in the grass.  Each species has a unique flash pattern determined by interval between flashes, flash color, number, rate, brightness, and how far the firefly travels between flashes.

The big dipper firefly, Photinus pyralis, has a black body, wings edged in bright yellow, a black and yellow belly, and the top of the head is yellow with a red patch and a black center dot.  Big dipper gets its name from its signature flash, starting bright and dimming as it swoops in an upward “J” arc.  The black firefly, Lucidota atra, has completely black wings, and a head topped in yellow with a large black center spot edged in red.  Black fireflies can emit light, but unlike other fireflies that flash to find a mate, they use pheromones.  The Pennsylvania firefly, Photuris pennsylvanica, is similar in appearance to the big dipper but only the outer edge of the wing is striped in dark orange.  They emit a yellow-green glimmer every few seconds, but females may flash the signal of the big dipper to attract a male of that species.  The female captures and eats the male to gain a steroid that naturally occurs in his body and makes the female taste bad to her main threat, jumping spiders.

Flashes are the result of a chemical reaction in specialized cells, called photocytes, located in the abdomen.  Oxygen is taken directly into these cells and combined with the chemical luciferin and an enzyme, luciferase.  The light emitted is controlled by limiting the amount of oxygen.  Fireflies produce cold light, one of the most energy efficient sources of light in nature.  Over 99% of the reaction produces light vs. about 10% from an incandescent light bulb where the rest of the reaction is heat.  In human medicine, luciferase, created from genetically engineered chemicals, is used to screen for tumors, blood diseases, and as a fast-acting detector of infection.

Fireflies live for a little over a year.  After mating, females will lay about 500 eggs.  Adults will die soon afterwards.  In about four weeks, the eggs will hatch and flat, worm-like larvae will spend the summer in moist areas under logs or leaf litter.  They are nocturnal and prey on earthworms, caterpillars, and other soft-bodied invertebrates.  As winter approaches, they will move to underground burrows and continue feeding until spring.  Their sickle-shaped jaws inject a toxin that helps to liquify the insides of their prey, allowing the larvae to suck out the nutrients.  Leaving their underground burrows in spring, they search for a mate and begin a new cycle.

Fireflies have been steadily declining over many years from habitat loss, pesticide use and light pollution.  We can help by mowing the lawn less often or leaving the grass taller in places to provide a  safe area.  Leaving leaf litter or rotting wood in garden beds provides for eggs, larvae and prey.  Avoiding pesticides, especially lawn applications, preserves healthy habitat.  An essential element to mating is the ability to see each other’s flashes.  Reducing our use of outdoor lighting provides darker areas so flashes are more visible and recognized.  I hope you enjoy this wonderful summertime phenomena in your own backyard theatre tonight!

During the summer, I take a walk around the yard every day to observe the dozens of insects in the garden. It is fun to identify the species and watch the activities they are engaged in and learn how they keep my backyard healthy and looking so wonderful.  Here are some of the insects I recently observed.

Bees, wasps, and flies often visit ‘Walker’s Low’ catmint, Nepeta faassenii, a purplish, low-spreading perennial that flourishes in bright sunny locations.  I most often see honey bees,  Apis mellifera, and cabbage white butterflies, Pieris rapae, visit the catmint.  Both insect species are taking nectar for food from the catmint.  They don’t stay long in any one place, and flit constantly from one flower stalk to another, taking small sips and moving on.

Another hotspot for insects is in the vegetable garden.  We have tomatoes, peppers, beets, carrots, parsley and dill, Anethum graveolens, an annual herb in the celery family used as a spice for flavoring food.  Dill is also a host plant for the Eastern Black Swallowtail Butterfly, Papilio polyxenes.  After the eggs hatch, the earlier stage caterpillar is black overall, with sharp orange spikes covering the body and a white “saddle” in the middle.  As the caterpillar matures, it will lose the spikes, turn light green with yellow spots and whitish stripes, then enter the chrysalis stage and eventually emerge as an adult butterfly.

Another winged insect you may see, the Crane Fly, a member of the Tipulidae family, has a bright orange body and glowing green eyes.  These insects can be found in moist woodlands or around bodies of water including a creek or pond running through your backyard.  They lay their eggs in water or moist environments, and the larvae live in the top layers of soil.  The larvae help to break down organic material in soils while the adults are an important food source for spiders, fish, small amphibians and birds.  The typical lifespan for an adult is only 1-2 weeks.

Monarch butterflies, Danaus plexippus, are starting to appear daily.  The monarch is the State Insect of Illinois, and it is found throughout the state in all habitats except deep forest.  Up to  three generations are born each summer, and the last generation in late summer / early autumn is migratory, flying to overwintering sites mainly in the high altitude regions of Mexico.  Monarchs are dependent upon the many species of plants in the milkweed family, Asclepiadaceae.  Eggs are laid on leaves and the caterpillars feed exclusively on species of milkweed.  In recent years, we have seen a decline in the number of milkweed plants everywhere in Illinois, but you can help monarchs by planting them in your own yards and encouraging local business and government to do the same.

The Japanese beetle, Popillia japonica, can be found on many plants in the garden.  It is an invasive species that does very little harm in its native country, but is a pest of over 300 species of roses, grapes, linden trees and numerous other plants.  The adults eat everything between the veins of the leaves, then the plants can no longer create their own food.  Japanese beetles display iridescent copper-colored wings folded over their backs behind a dark green head.  Several insects and parasitoids have been brought into the U.S. to control these beetles, with limited success.  Traps have also been developed, but data suggests that these merely entice the beetle to a host plant.

The common green bottle fly, Lucilia sericata, also known as a blow fly, is a member of the fly family, Calliphoridae, comprising over 1200 known species.  Members of this family occur worldwide in almost every location that includes humans.  Adult flies feed on carbohydrate-rich nectar in the garden, as well as any decaying meat or garbage.  Dumpsters and garbage containers accessible from outside may attract flies in huge numbers.  Eggs are laid on carrion and larvae feed on the carrion.  The time period from egg to adult can be between 2 and 4 weeks, and a female may lay 10-15 clutches of 200 eggs each in her lifetime.  The best control for these insects is to keep refuse covered at all times.

Nights in your backyard at this time of year are filled with spectacular light displays created by lightning bugs, otherwise known as fireflies.  There are over 170 different species in the U.S., and fireflies can be found in every state except Hawaii, and on every continent except Antarctica.  The flashes are a form of communication, mainly for trying to attract a mate.

Not all fireflies in the U.S. are ‘flashers’.  Some species are active only during the day and do not emit any light; several species are known as glowworms and emit a steady, glowing light.  Here in the Midwest and farther east, most species are ‘flashers’.  Flashing is a form of communication used in seeking and finding a mate.  The light is a byproduct from a bio-chemical reaction of oxygen with the enzyme luciferan plus ATP and manganese.  Different species will emit different colors of light from green to yellow to orange.  Colors can also be influenced by what time of day it is and how well they will show up against the background colors of the habitat.  Firefly enzymes have been widely studied by medical research facilities where doctors have been able to inject the enzymes into a test specimen and  duplicate the light emission to provide imaging of internal cell structures.  This procedure, known as bioluminescence imaging, is at the forefront of emerging technologies for studies of viral infection.

Fireflies are part of the beetle family and as in all species in this family, they undergo complete metamorphosis including four stages: egg, larva, pupa, and adult.  Fireflies lay eggs in late summer in rotting logs, moist soil or deep mulch.  Larvae hatch in three to four weeks, and they are voracious predators of soft bodied invertebrates including snails, slugs, spiders, and earthworms.  Larvae live from one to two years, overwintering underground or deep in rotting wood.  They molt often during this stage of eating and growing.  Larvae pupate in late spring either in an underground burrow or in some species, by attachment to a tree branch where they hang upside-down.  In two to several weeks, depending on the species, a biochemical transformation will take place changing the larva into an adult.  After adults emerge, their only function is to reproduce.  Adults generally do not eat, but may sip nectar or maple sap as a secondary source of moisture.   They live only a few weeks finding a mate and laying eggs  before they die.

Fireflies can be found in a wide variety of habitats including rivers, valleys, ponds, fields, marshes, forests, cities and urban areas.  There has been very little scientific study of firefly population characteristics, and we are just starting to accumulate this data.  Therefore, little is known as to whether they are declining, but there is anecdotal data to suggest that there were many more fireflies thirty to fifty years ago.  It is known that 3/4 of all species are active only at night.  Species in our area can be affected by habitat loss, herbicide use, and artificial night light which can obscure firefly communication and adversely affect breeding success rates.

It is fun and entertaining to be out on a quiet evening and enjoy the light displays being put on by these small insects.  You can help keep their populations strong in several ways.  Retention of leaf litter and logs, especially rotting wood, in forested or other areas will provide spaces for egg laying and larvae to live.  Consider reducing outdoor lighting at night including garage and walkway lights and buildings with all night lighting.  The use of motion detectors on timed circuits so lights are only on for a limited amount of time will greatly cut down on the amount of light present at night.  We hope you get out to see these wonderful gems, but remember if you are out looking for fireflies that flashlights, cell phones and camera flash units are all forms of artificial light that are best avoided to enhance your outdoor viewing experience.

We are hearing a lot of buzzing in our backyards right now.  The sound is coming from one of the loudest insects found anywhere in the world, cicadas.  Cicadas are members of the family Cicadidae, and are they close relatives of leafhoppers.  Sometimes misnamed as locusts, cicadas are non-jumping insects not at all related to either locusts nor grasshoppers.  There are over 150 species of cicadas in the U.S., with about 12 occurring here in northeastern Illinois.  The cicadas we see and hear are all adults; some are species that we see every year, and some are species known as “periodic species” that only appear every thirteen or seventeen years.

Species seen each year usually live underground for two to four years with some portion of the population emerging every year as adults.  Periodic species will live either 13 or 17 years underground and all of the population will emerge together in one year.  After emergence, adults go through one final molt to climb out of their old skin, pump blood into their wings and then let the wings dry and harden.

During this time, we may see hundreds of empty skins hanging from plants only to fall off and decompose.  Adults will then mate, lay eggs, and die.  Eggs are placed in holes or slots cut into tree limbs by the adult female.  They hatch after a few weeks, and the young crawl to the edge of the branch and drop off into the soil below.  They burrow their way underground and attach themselves to tree roots, where they will live until adulthood by sucking on tree sap.  A large population of individual cicadas living in a specific location is called a brood.  Twelve different broods of 17-year cicada species and three broods of 13-year cicada species have been identified throughout the eastern half of the United States.  In addition to a unique location, each brood emerges in a different year. 

Each species of cicada has its own distinct song, but all cicadas create their sound from a unique pair of organs called tymbals.  They are located on either side of the abdomen and consist of a membrane stretched across ribs.  As muscles contract, each rib buckles against the membrane with a snap.  A special air sac located in the same area amplifies the sound.  A cicada can perform this action several hundred times per second, and the resulting sound is a loud buzzing that can be heard for long distances. 

Cicadas are daytime singers and each species sings in a particular portion of each day.  In most species, only the males sing, and they start with a calling song, trying to attract a female.  When an interested female comes close, she will signal her presence with a snap of her wings.  Once the male hears her, he will change his song to a courtship tune that attracts her further and has her snapping her wings more vigorously.  This helps to guide the male to her and after locating her he will sing a third tune, a mating song.  

I encourage you to listen for the different songs sung by the male throughout the courtship proceedings as well as different songs from the three to four species currently active in this area.