HEARING - tree crickets 'hear' through a membrane on their forearms.
The membrane is easy to see on this dark 'arm' of a Forbes' tree cricket.
This close up of the femur shows tiny bristles -- which would certainly not be visible without a close-up shot from a camera or if viewed under a microscope.
Leg Markings A set of markings often helpful in ID ing Fast-calling tree crickets is on the 'knee' of the hind leg. There are three black marks on the femoral-tibal joint, and 2 black rings on the tibia. These are NOT, however, ALWAYS evident.
The undersides of tree crickets are interesting structures.
This is a side view of a male abdomen. Note the lack of an ovipositor -- on a fully developed tree cricket, females have longovipositors.
Here is a different view of the underside of a male O. forbesi tree cricket.
This is the underside view of the abdomen of a female Black-horned tree cricket. Here the ovipositor is clearly visible. (Note: You can also see the hearing membrane.)
As tree crickets grow in size before becoming a mature adult, they shed their outer skeleton, the exoskeleton, five times. The empty hard shell is then called an exuvia.
This is the exuvia of a Pine tree cricket. Note the rusty color on the head and rear legs of the exuvia.
The wings of this newly molted O. walkeri will straighten out within an hour as they dry. Tree crickets eat their exuvia shortly after molting.
Tree cricket eyes come in many colors. This Black-horned tree cricket has green eyes.
This male Four-spotted tree cricket has purple eyes.
This Black-horned tree cricket has white eyes.
This Walker's tree cricket has yellow eyes.
METANOTAL GLANDS - males have a gland on their 'back' which secretes a fluid that attracts females.
The metanotal gland is located just behind the wings.
Close-up view of the metanotal gland.
View of the metanotal gland on a male Snowy tree cricket.
The metanotal gland is only visible when the male has his wings in the upright position to sing.
Close-up view of the metanotal gland on a male Four-spotted tree cricket.
The metanotal gland of the Pine tree cricket has a pinkish interior and reddish brown rim.
This is a microscope view of the metanotal gland of a Symes' tree cricket.
Antennal Markings -- -- most species of tree crickets have black markings on the first and second segments at the base of their antenna. When present, these markings are useful in making an identification of species. Here are some examples:
This is one variation for Forbes' Tree Cricket. The two marks on the 2d segment join at the bottom to form a ' V ' pattern.
Another variation in antennal markings for Black-horned Tree Cricket. The two marks on the 2d segment are separated.
The antennal markings for Forbes' Tree Cricket are similar in configuration to Black-horned Tree Cricket, and often the head color is similar to that of Four-spotted Tree Cricket. The only way to make a definite ID for Forbes' is by the calling rate of the male in given temperatures.
The Fast-calling Tree Cricket is another member of the nigricornis group -- whose antennal markings are all very similar. The Fast-calling's 2nd segment has two vertical lines -- the outer being shorter than the inner marking.
The markings for the Four-spotted Tree Cricket are somewhat similar to the Black-horned; however, note the difference in the outer marking on the 1st segment. Instead of a tapered horizontal marking on the outer edge, there is a round spot.
Although the Pine Tree Cricket is easily identified by coloration, they do have markings much like the Black-horned Tree Cricket.
These are the markings for Narrow-winged Tree Cricket. Note the ' j' shape of the marks -- with the tell-tale hook on the 1st segment.
The markings for Davis' Tree Cricket are similar to those of the Narrow-winged Tree Cricket. Note, however, that the mark on the 1st segment does not have that ' j ' like hook. Rather, the markings have an 'upside down exclamation mark' appearance. (Hence the name - Oecanthus exclamationis.)
The Snowy Tree Cricket has two black spots, basically equal in size, one on the 1st segment and one on the 2d segment. (Not pictured is the Riley's Tree Cricket - which has markings very similar to the Snowy Tree Cricket. However, Riley's has a smaller mark on the 2d segment.)
The antennal markings on Alexander's tree cricket is very similar to the Snowy tree cricket. The only way to ID this tree cricket is by its song. Snowy tree crickets have a continuous chirping pattern; Alexander tree crickets have bursts of chirps and then pauses before another burst of chirps.
This is a close-up view of the markings for Oecanthus allardi from Nicaragua. The white background with black spot is a characteristic of the rileyi group.
The Different-horned Tree Cricket has black antennae. The first two segments are deep red and have a black straight line.
The 'singing' apparatus found on the forewings of males consists of a row of 'teeth' which rub against a 'scraper'. A row of well-formed teeth are usually on the underside of the right forewings. This row is less than 2mm long. The number of teeth varies with each species - i.e. some have 20 teeth, others have 45, some have 90 - etc. The right forewing rubs against the scraper on the top side of the left forewing.