FEBRUARY 28 – Vision ?
This is one aspect of observing tree crickets that puzzles me. You can be walking near plants, and one tree cricket will dart under a leaf, one might jump to the ground, and then there’s that one that just sits there.
You can be out after dark and shine a light on a singing male, and he might stop singing and dart off…and then another will just sit there and keep singing – even if you shine the light in their face.
I have seen this behavior rather often – a pair of tree crickets in a confined space with the female ‘hiding’ under a leaf, and the male seems to have no idea where she is! Why can’t he see her, or smell her with his antennae?? He knows she is there because he was just touching her! ??
…and how about this guy? Yikes. His vision and olfactory are both off. It is late in the season, his coloring is yellowed from old age, and his song sounds weak…apparently confusion has also set in.
Tomorrow: March will be a month of species
FEBRUARY 27 – Flying and Leaping
I do not know a great deal about the flying ability of tree crickets. I have personally witnessed ‘travelling’ four times. The first involved a female Narrow-winged tree cricket. I placed her on some vegetation, and she made what I call a flying leap. From what I have seen, they do use their wings, but don’t seem to be able to sustain flight. She leapt a distance of about 3 feet.
The second episode involved a Two-spotted tree cricket. I had placed it on a patio plant. It moved onto an adjoining railing, and then took a flying leap to a different plant. This flight was about two feet in length. I know it doesn’t look like much of a photo – it was taken out of this video…but bear in mind it happened suddenly, required a hand held light, and lasted a few seconds!
The third episode was a male Walker’s tree cricket. It leapt about four feet.
All three of these events occurred after the tree cricket had been contained and then released.
The last episode involved a female Snowy tree cricket. She had been net-contained outdoors on a hibiscus shrub for several days/nights. For two nights, a male Snowy tree cricket had been singing all evening in a nearby patch of hazelnut saplings. I noticed on the second night that she seemed restless and continually climbed to the top of the netting and faced toward the singing male. I filmed her as soon as I removed the netting. At first she sat on the very top of the top leaf, facing the male, as if she was getting her bearings.
Then she leapt about four feet…landed on a stem and made her way back to the top….then she again pointed toward the male and took another leap.
Eventually, she covered the 15-foot distance, mostly leaping – some walking horizontally along vegetation, but never walking on the ground, and parked herself under a leaf within inches of the singing male.
Tomorrow: Vision ?
FEBRUARY 26 – Grooming
This day is easy! Just a bunch of videos of tree crickets grooming various body parts.
FEBRUARY 25 – Eating and Chewing
Note the brown, pointy ‘teeth’, which are actually hooks on the mandibles (mandible, mandibular – BugGuide.Net). If you have ever been nibbled upon by a tree cricket, you definitely feel it, but it isn’t traumatic.
Tree crickets are omnivorous. They eat insects smaller than themselves, i.e. aphids. They also eat plant materials, i.e. leaves, fruits and bark. Other favorites…commercial cricket food and cat food! (BTW, I no longer use plastic inside containers.)
This little Neoxabea bipunctata nymph is nibbling on bark of a stem from an apple tree.
This young nymph is eating aphids.
This adult female is eating commercial cricket powder.
This adult female is eating flower petals.
This female is eating off of a piece of raspberry.
FEBRUARY 24 – Palpi and Grabbing
Tree crickets come straight out of the egg with palpi. (I have always used the term ‘palps’…I have seen both used.) This little tree cricket is less than 15 minutes old.
They have a total of four palpi…two on the left and two on the right, two on the labium and two on the maxillae. An excellent drawing can be found here: insect-mouthparts.png (1155×1131) (wordpress.com)
Neoxabea tree crickets tend to have markings on their palpi. Below are: N. bipunctata, N. cerrojesusensis and N. ottei. Both N. cerrojesusensis and N. ottei are found in Nicaragua / Central America.
The colors of Oecanthus palpi varies as much as the tree crickets themselves.
Note the sharp structures in the last photo…they will be covered in tomorrow’s blog.
Here are two examples of how they use their palpi to gather and manipulate food:
FEBRUARY 23 – Ovipositor
It isn’t difficult to guess what ovipositor means. It comes from Latin ‘ovum’ (egg) + ‘positor’ (one who deposits).
What is difficult, at least for me, is getting a video of an egg actually being passed from the female into a stem ! I have tried different methods for many years…still no luck. Maybe this year! 😉
Although an ovipositor is usually described as tube like, the ovipositor of a tree cricket is two adjoining appendages which manage to stay connected as a single entity, even though they can manually be separated. They do seem to have slightly different appearances – but they all manage to drill into vegetation stems and tree branches. Even though the photos are not stellar…they do offer some comparisons.
The ovipositor is pale during the nymph stage and immediately after molting.
The ovipositor is long and sturdy, and appears to have ridges. Perhaps these act as files to smooth the edges of the hole as the female maneuvers her ovipositor.
Females keep their ovipositor clean by grooming them with their mouth.
Look how the palpi are on either side of the ovipositor to guide it for grooming.
Note the super long ovipositor on Oecanthus major which can be found in Mexico and southern Arizona. Cricket or Katydid? – Oecanthus major – BugGuide.Net
FEBRUARY 22 – Gravid Females
These are eggs inside a female – waiting to be oviposited.
Seeing how many eggs can fit inside a female, I find it easier to comprehend how many eggs BB Fulton determined are laid overnight (Fulton’s 1915 paper: s576lf15.pdf (orthsoc.org)) …
…than other estimates I have seen that counted 75 in one night. Creating and growing 75 eggs in less than a 24-hour period seems like a remarkable feat for a female’s body…but I have to remind myself that it is also amazing to know that some male’s wings open and close up to 120 times per second! Or perhaps I misread the other article…and they were speaking of Fulton’s documentation of 75 eggs over more than one night by a single individual.
I believe tree cricket females start developing eggs before they even encounter a male…but I don’t know at what stage they start developing. I once had three adult female Oecanthus niveus in a large container with stems and leaves, and two of them began drilling into the stems. I don’t know (or I don’t remember) if the stem had unfertilized eggs vs no eggs at all…perhaps they were just drilling.
Apparently a female is considered gravid even if her eggs have not been fertilized by male sperm. I don’t know if unfertilized eggs within a female are smaller in width than fertilized eggs, but here are some photos of females with plump abdomens.
A reminder – the abdomens of tree crickets with horsehair worms or fly pupae will be grossly distended.
FEBRUARY 21 – Eating the Spermatophore
Female tree crickets use their mouths to remove the spermatophore and then eat it. If you concentrate on only the face and palps, it looks just like a spider rolling its prey.
This gal is trying to remove the spermatophore, but the male keeps pestering her. His motives are probably 1) keeping her from removing the spermatophore too early, and 2) inserting another spermatophore.
Although not focused on tree crickets, this article’s abstract gives some info on ingesting spermatophores. Ingested spermatophores accelerate reproduction and increase mating resistance but are not a source of sexual conflict | Request PDF (researchgate.net)
This paper gives information on nutrients in spermatophores: (PDF) Carotenoids in the spermatophores of bushcrickets (Orthoptera: Ephippigerinae) (researchgate.net)
Here is some information regarding the formation of a spermatophore: Detailed developmental morphology of the spermatophore of the Mediterranean field cricket, Gryllus bimaculatus (De Geer) (Orthoptera: Gryllidae) – ScienceDirect
FEBRUARY 20 – Transferring the Spermatophore
This video shows several acts of interest: 1) The female appears to be trying to remove the spermatophore, and seems to be chewing even though the spermatophore is still attached…perhaps she removed a remnant of the tube of a second spermatophore? 2) The male keeps trying to entice her to feed from his metanotal gland in order to insert another spermatophore. 3) The female starts grooming her palps and antennae. 4) The male is attempting to move the female into place by using his limbs. 5) The male successfully transfers another spermatophore. Note how this new spermatophore is much lighter in color than the one already in place. 6) Note the male’s subgenital plate. Perhaps the movement indicates he is forming yet another spermatophore!
This video also shows the insertion of a spermatophore. While someone with good eyes might be able to actually see the copulatory blades in action (I can’t even with a magnifying glass), we know when the spermatophore tube has been fully inserted because we can see the spermatophore drop off the male into place.
Here is another transfer video. Here it appears the female is biting the male’s metanotal gland…he just about gets into position to transfer the spermatophore and then suddenly pulls away from the female. I can’t imagine any other reason for him to chance not being able to pass on his sperm.
This last video is showing a female in position, feeding from the male’s metanotal gland. Note how the male’s hindwings are constantly moving. I do not know if this is in response to the female feeding at the metanotal gland…or if he is trying to touch the female’s abdomen to encourage her to arch it so he can reach her openings. Maybe it is neither.
Something I have yet to do is to witness the actual transfer of a spermatophore on a dangling pair of Neoxabea bipunctata.
FEBRUARY 19 – Female Openings and Spermatophores
Dr. Bentley Ball Fulton has a description of the female reproductive organs here: s576lf15.pdf (orthsoc.org)
The openings are situated on each side of the base of the ovipositor:
The spermatophore is attached to the female through one of these openings…a tube on the spermatophore permits drainage of the sperm into the female. The very thin tube compared to the comparatively large spermatophore helps one to understand why the male continues to expose his metanotal gland, at times singing, to keep the female from removing the spermatophore too soon – he wants the spermatophore to drain as long as possible to prevent wasting of his sperm.
This male has kept this female occupied long enough for a second spermatophore to form. It sits upon his subgenital plate awaiting transfer.
I have witnessed three females with two spermatophores in place. Surprisingly, all three had both spermatophores inserted on the same side.
FEBRUARY 18 – Spermatophore
The spermatophore is a capsule containing spermatozoa created by males, and transferred to the female during reproduction. Spermatophores may additionally contain nourishment for the female, in which case it is called a nuptial gift.
Fulton has great drawings here: s576lf15.pdf (orthsoc.org)
The abstract of this paper gives good information about arthropod spermatophores: Spermatophore (researchgate.net) Spermatophore – ScienceDirect
Reminder: I do not have sophisticated photography equipment.
The first photo shows a spermatophore plump with liquid and sperm, with the insertion tube attached. The second photo shows the spermatophore still in place with the copulatory blades. The third photo shows the spermatophore partially nestled in the subgenital plate’s pouch (which bulges to accommodate the spermatophore), with the copulatory blades visible and the cerci at the top. The fourth photo shows a spermatophore and copulatory blades.
Dr. Bentley Ball Fulton describes it (s576lf15.pdf (orthsoc.org)) this way:
The photos below show females with a spermatophore in place.
This photo shows a pair of Forbes’ tree crickets. The female already has an attached spermatophore, while the male has another one ready to be transferred.
This video shows movement of an attached spermatophore.
Here is another paper focused on mating and spermatophores: (PDF) Size-biased Mating in Both Sexes of the Black-horned Tree Cricket, Oecanthus nigricornis Walker (Orthoptera: Gryllidae: Oecanthinae) (researchgate.net)
FEBRUARY 17 – Internal Genitalia
The internal genitalia of the male includes the copulatory blades – which are the appendages responsible for securing the female’s opening during the transfer of the spermatophore. They have also been referred to as claspers or copulatory blades.
Note: These photos are not ideal…the entire structure in each photo below is only 1mm in length…too small for my equipment. They do, however, show the differences in shape of the blades.
Copulatory blades (main lobes of pseudepiphallus) of various species. The first row shows members of the nigricornis species group.
This row shows members of the varicornis species group.
Left shows Oecanthus fultoni (member of the rileyi species group) and right shows Neoxabea bipunctata.
Dr. Fulton referred to them as copulatory blades: s576lf15.pdf (orthsoc.org)
Did you notice that the copulatory blades on this Oecanthus forbesi, with a single bright spot of reflection as the head, the two blades give the illusion of a tiny little person? 😉
Here is a paper in French with diagrams: Annales de la Société entomologique de France | 1987-07-01 | Gallica (bnf.fr)
FEBRUARY 16 – Subgenital Plates
Here are some female subgenital plates…at the base of the ovipositor. They have a notch of varying depths between the two sides.
The subgenital plate of the male has a single tip, either rounded or pointed.
More images of subgenital plates on other orthoptera and other insects: subgenital plate of orthoptera – Bing images
Although this paper covers grasshoppers, which have a different sperm transfer action, it has nice drawings to show the differences in shape of subgenital plates of different species: (PDF) Taxonomic Significance of Male Supra-anal Plate, Cerci and Subgenital Plate in the Classification of Indian Pyrgomorphidae (Orthoptera: Pyrgomorphoidea) (researchgate.net)
The male subgenital plate acts a bit like a holding shelf for a spermatophore that is ready to be passed to a female.
FEBRUARY 15 – Antennal Filaments
Tree crickets have filiform antennae. filiform – BugGuide.Net
antenna, antennae, antennomere – BugGuide.Net
Although certainly not the best photos, they did allow me to assess the lengths of individual segments / antennomeres on different species.
I did notice three of these photos of adults are displaying segment patterns like the below diagram for the first 25 segments. At least two others, however, have the 1st long segment at #12, not #11.
Dr. Fulton has excellent drawings of the length of the antennae for each instar stage, showing how the antennae grow along with the tree cricket: s576lf15.pdf (orthsoc.org)
This abstract gives a nice overview of the functions of arthropod antennae: A tunable physical model of arthropod antennae | IEEE Conference Publication | IEEE Xplore
FEBRUARY 14 – Neoxabea Tubercles
Neoxabea has raised tubercles on the pedicel, scape and abdomen tergites.
These photos show these raised knobs on the 1st and 2nd antennal segments.
Oecanthus tree crickets have a smooth dorsal surface of the abdomen, while Neoxabea tree crickets have tubercles or knobs.
Given the mating process of Neoxabeans, perhaps the knobs offer an emergency handle ??
Information about the knobs from Walker’s paper here: s576lw67.pdf (orthsoc.org)
FEBRUARY 13 – Cerci and Setae
seta, setae, setaceous, setose, etc. – BugGuide.Net
The length and shape of the cerci varies by genera of tree crickets. Oecanthus has straight cerci, and Neoxabea has curved cerci. The cerci of female Oecanthus in the US are generally the same length – nearly to or just barely past the tip of the ovipositor.
Females are able to manipulate their cerci while ovipositing. (Oecanthus forbesi on left and Neoxabea bipunctata on right.)
The length of the cerci on Oecanthus males has an associated optical illusion based on the length of their tegmina. Those with short wings seem to have long cerci, while those with long wings seem to have short cerci. Actually, they are very close to being the same length.
Watch this male Oecanthus move his cerci:
The shape of the cerci on Neoxabea has been described as a loose S-shape. The third photo below shows the developing cerci on a 5th instar of Neoxabea bipunctata.
Note the numerous setae on all of the cerci photos in today’s posting. These setae can be found on many parts of a tree cricket, including the femora. The photo on the leftt is Oecanthus salvii, the only pale green tree cricket in the US with numerous deep black setae on the femora.
Here is a nice photo showing setae on the pronotum: Otomi tree cricket from Fraccionamiento Vista Real, 76905 Corregidora, Qro., México on December 02, 2021 at 08:06 PM by Coronado Govaerts · iNaturalist
This photo shows that Neoxabea has many setae, including on their palps and on their limbs: Two-spotted Tree Cricket from Virginia Polytechnic Institute and State University, Blacksburg, VA, US on September 26, 2022 at 04:25 PM by RichX 915 · iNaturalist
They even have setae on their antennae.
FEBRUARY 12 – Oecanthus Abdomen
Diagram of an insect – BugGuide.Net
This BugGuide diagram shows: Tergites, Sternites and Respiratory Spiracles
tergum, terga, tergite – BugGuide.Net
sternum, sterna, sternite – BugGuide.Net
spiracle, spiracles, spiracular – BugGuide.Net
trachea, tracheae, tracheal – BugGuide.Net
The pattern on the abdomen of nymphs can be helpful in identifying them to species. Very young Snowy tree crickets have straight rows of evenly spaced white dots…Riley’s has the same pattern. Alexander’s also has straight rows of white dots. These are all members of the rileyi species group.
One trick for determining Narrow-winged tree cricket is to look at the underbelly (aka ventral abdomen or sternites). This species tends to have a purplish appearance of the ventral abdomen.
Many species in the nigricornis species group have dark coloring on the ventral abdomen.
Species in the rileyi and niveus species groups have pale coloring on the ventral surface of their abdomen.
Members of the varicornis species group vary – some are pale and some have color. The pictipennis form of Western tree cricket is very dark; Texas tree cricket is very pale.
Tree crickets ‘breathe’ through openings on the side of their abdomen. These spiracles allow air flow to the air tubes or tracheae. Insect Breathing | Ask A Biologist (asu.edu)
This paper can be downloaded if you register at ResearchGate (it’s free): (PDF) Why Do Insects Close Their Spiracles? A Meta-Analytic Evaluation of the Adaptive Hypothesis of Discontinuous Gas Exchange in Insects (researchgate.net)
Here is another paper: (PDF) Transitions in insect respiratory patterns are controlled by changes in metabolic rate (researchgate.net)
FEBRUARY 11 – Metanotal Gland
The metanotal gland of a male tree cricket secretes a liquid that is enticing to females. By sipping this liquid, it puts the female in a perfect position for the male to transfer a spermatophore. He continues to sing intermittently in order to convince her to continue feeding from the gland…so she will not prematurely reach back to remove the spermatophore. His intention is to keep it in place for as long as possible to increase the amount of his sperm fertilizing the eggs within her.
These are some of my favorite metanotal glands:
Oecanthus symesi (which should technically have been O. symesae) – this one reminds me of the Rolling Stones
Neoxabea sp. nov. from Honduras (description in progress) – this one reminds me of the inside of a peach
Oecanthus leptogrammus (specimen from Nicaragua) – this one reminds me of an open mouth of a hippopotamus
Oecanthus californicus pictipennis (hopefully will be O. pictipennis with DNA results) – this one reminds me of a piranha
Neoxabea bipunctata – this one reminds me of a barbershop quartet singer
More species:
This paper provides nomenclature for the various parts in the metanotal gland: s576lwg67.pdf (orthsoc.org)
Here is a paper with drawings of different species (mostly south of the US): s576lw67.pdf (orthsoc.org)
Here is a male Four-spotted tree cricket with his wings raised and metanotal gland exposed.
Even if you cannot access the entire article, this abstract gives some information regarding metanotal gland secretions: Allocation of nuptial gifts in tree crickets changes with both male and female diet on JSTOR
FEBRUARY 10 – Pronotum
pronotum, pronotal – BugGuide.Net
I must admit I could not find much information for the reason for such a prominent protective plate in this spot online. In crickets, the heart is located further down the abdomen, and the brain is found in the head. I imagine it offers protection of the trachea, esophagus and nerve cord at an otherwise slender area. Perhaps a bonus: protection from being decapitated by a predator ??
The pronotum is present on 1st stage instars, and develops with each subsequent stage. Here is a 5th instar:
Dr. Bentley Ball Fulton provided a wonderful drawing in his 1915 paper here: s576lf15.pdf (orthsoc.org)
Oecanthus and Neoxabea pronotums are narrow at the proximal end and wider at the distal end, and come in a variety of colors. Those of Neoxabea are the most ornate.
Below is a close-up view of the proximal edge and the distal edge of the pronotum on a Neoxabea from Nicaragua:
One species, Oecanthus prolatus (with a body length of 16-19mm), has an unusually long pronotum – measuring up to 4.1mm. Even Oecanthus major, the largest North American species with a body length of 18-20mm, has a pronotal length less than 3.7mm. To get a true appreciation of the length of the pronotum of Oecanthus prolatus, look here on iNaturalist: Oecanthus prolatus from Colón, Panama on January 20, 2012 by Katja Schulz. Seen on a night walk. Barro Colorado Island, Panama. 20 January 2012 · iNaturalist
FEBRUARY 9 – Limb Markings and Coloring
Markings can be helpful when identifying nymphs. They can, however, appear much different than they do in adults. This Snowy tree cricket nymph has black speckling on the limbs, with double black rings on the tibiae. Adults have neither of these characters.
Some adults have coloring on the femoro-tibial joint, aka knee. Some have markings, but these can vary. The pine tree cricket (Oecanthus pini) has rust coloring at the knee. A darker color form further west has white, which is a bit surprising given their otherwise remarkable camouflage coloring. Perhaps the white color is meant to emulate dripping resin. 😉
Oecanthus varicornis (L), Oecanthus texensis (C), and Oecanthus californicus (R) tend to have orange knees.
Oecanthus forbesi and Oecanthus nigricornis don’t follow any rules…they can vary in color from all green to green with all black head, pronotum, antennae and limbs.
Whatever color the insects legs are, the femoro-tibial joint seems to be another color, or at least a bit lighter or darker than the rest of the limb. Why is that?
I’m not sure if these same principles apply to Orthoptera (this paper focuses on Coleoptera)…but could the presence of some type of lubricant there have anything to do with the color? I don’t know…I’m asking 😉 (PDF) Insects use lubricants to minimize friction and wear in leg joints (researchgate.net)
One helpful limb marking character is double or single black rings on the hind tibiae. Usually only O. celerinictus has them on the middle or even a faint marking on the front tibiae, but you can’t rely solely on these markings, since Forbes’, Black-horned and probably Prairie can sometimes have these markings on both the middle and hind tibiae.
However, not all individuals have the rings. There seems to be a population in Texas without rings. This makes indentifying them more difficult.
More information about the femoro-tibial joint here: (PDF) Jumping and Grasping: Universal Locking Mechanisms in Insect Legs (researchgate.net)
FEBRUARY 8 – Claws and Exoskeleton
The claw on the left is from Oecanthus, and the two claws on the right are from Neoxabea.
The claws of a tree cricket are tiny but mighty.
Consider their capabilities when a 5th stage instar molts into adulthood. It hangs by the claws…only the claws portion on the exoskeleton…so gravity assists it in ‘falling’ out of the exoskeleton. Now imagine the sturdiness of the exoskeleton that covered the claws!
The claws are also essential for Neoxabea bipunctata females to grasp the male during the mating process. If one didn’t know better, they would assume the top tree cricket was trying to get rid of the lower one. We will cover mating in another month.
The structures covered by the exoskeleton are amazing…the claws, the antennae, and even setae.
Tree crickets generally eat the exoskeleton after molting.
Here are some papers regarding the exoskeletons of insects:
Fracture toughness of locust cuticle | Journal of Experimental Biology | The Company of Biologists
Fatigue of insect cuticle | Journal of Experimental Biology | The Company of Biologists
Here is an in-depth piece on insect morphology – including exoskeleton: Insect morphology – Wikipedia
Tomorrow: Limb Markings and Coloring
FEBRUARY 7 – Femora and Tibiae (Femurs and Tibias)
Sometimes investigators of a potential new species get lucky and find a character or two that are not seen on otherwise similar looking species. That was the case for Oecanthus salvii (Sage tree cricket). No other very pale species has numerous black setae on the femora.
Very young nymphs do not have the sharply spiked spines of adults, but rather numerous small setae. At least I have always assumed that is what they are.
As they develop, the spines are more evident – as in this 5th stage instar of Oecanthus forbesi.
This fourth stage instar has spines as prominent as that of an adult.
Adults have both short and long spines on their tibiae.
These are also referred to as tibial armature…a fitting term indeed.
It is curious that species of Oecanthus have this armature, whereas those in the genus Neoxabea do not.
From my experiences, it seems that tree crickets are not strong fliers…but rather good leapers. They can’t jump like grasshoppers. They can fly…but not like a katydid (this will be covered in another month). Those that I have seen travel over a relatively long distance take a ‘flying leap’. This female Snowy tree cricket had been sleeved where a Snowy male had been singing 15 feet away for two nights. As soon as I removed the sleeve, she immediately pointed herself in his direction as he sang and took about five flying leaps to get to him.
This article is too deep for me, and is not focused on tree crickets, but it certainly sounds interesting: (1) (PDF) A load-based mechanism for inter-leg coordination in insects (researchgate.net)
FEBRUARY 6 – Tympanal Membranes
(Day 37)
An amateur’s close up of tree cricket ears.
If they wore clothes, tree crickets would wear their ears on their sleeves. These ears, or tympanal membranes, are located on their forelimbs.
This tree cricket’s ear is positioned in a spot we expect it to be 😉
For a number of articles focused on tree cricket sounds and hearing, go to Dr. Natasha Mhatre’s Lab site here: MHATRE LAB – Home (natashamhatre.net)
Here is one paper: Stay tuned: active amplification tunes tree cricket ears to track temperature-dependent song frequency | Biology Letters (royalsocietypublishing.org)
Here is another: A Tympanal Insect Ear Exploits a Critical Oscillator for Active Amplification and Tuning: Current Biology (cell.com)
Tomorrow: Femora and Tibiae
(Day 36)
Tree cricket eyes come in a variety of colors.
Check this posting to iNaturalist for a tree cricket with beautiful red eyes: Tree Crickets (Subfamily Oecanthinae) from San Mateo Rio Hondo, Oax., México on December 09, 2019 at 09:00 AM by Erick Noe Tapia Banda · iNaturalist
My observation of tree cricket eyes, aside from different coloring, is that I have personally never witnessed a tree cricket’s eyes following my movements, and I know little about the physiology of their ‘pupil’. Apparently it is actually a pseudopupil: Pseudopupil – Wikipedia
More about compound eyes here: Compound eye – Wikipedia
A paper focusing on the evolution of insect eyes: (1) (PDF) Evolution of Insect Eyes: Tales of Ancient Heritage, Deconstruction, Reconstruction, Remodeling, and Recycling (researchgate.net)
Human vs Insect Eyes: How Insect Eyes Differ From Ours | Arizona RETINA Project
and Insect Compound Eye vs. Human Eye | Sciencing
FEBRUARY 4 – Antennae
(Day 35)
Well, despite already having shown this, I absolutely have to start out by showing my all-time favorite tree cricket video. This little Oecanthus californicus was about 10 minutes out of the egg, and seemed to be checking out what he could do with his antennae!
Young nymphs are extremely difficult to find in vegetation. They tend to stick close to leaf indentations near the stem, on the underside of leaves, or in curled, dried leaves. I find the easiest way to find these hidden little stinkers is to look for their antennae!
Most Oecanthus species in the US have black marks on the 1st and 2nd antennal segments. A handful have unique markings, but many look similar. If only every species had unique marks…it would make identifications soooooo much easier.
Oecanthus niveus (Narrow-winged) is the easiest to identify. They have a mark shaped like the letter J on the 1st segment. However, camera angles can cause distortions. I have seen photos that look like Snowy or Riley’s tree crickets…with a single black rounded mark on the 1st segment. What is actually being seen, however, is the rounded inward curve of the distal end of a J.
This can also make identifying Oecanthus exclamations (Davis’) tricky. When viewed from the front, the upside down exclamation mark is very apparent. However, some camera angles make it difficult to know if there is an inward curve of the black mark at the bottom of the 1st segment.
And then there is a population found in southern Arizona that look like a cross between Narrow-winged, Snowy and Davis’. In addition, the shapes vary. In the eastern US, the shape never strays from an upside down exclamation mark for Davis’, rounded dots for Snowy and a ‘ J ‘ for Narrow-winged. A specimen was sent to Texas A & M University for DNA analysis – results pending.
One easy species to identify is Oecanthus quadripunctatus (Four-spotted). They have a round mark on the upper outer portion of the 1st antennal segment.
Well…I guess I should add they are easy to ID when they DO have that single dot. Sometimes that upper outer mark looks like many of the other members of the nigricornis species group. This group is the hardest to determine as the markings can vary only slightly between species – since each species also has a range of markings. The diagram below (from SINA) is from page 73 here: s576lw63.pdf (orthsoc.org)
Oecanthus fultoni (Snowy) and Oecanthus rileyi (Riley’s) have remarkably similar appearances – with only slight differences in the black dot on the 2nd antennal segment. Again, here are diagrams from SINA – a vital source for the understanding of tree crickets:
snowy tree cricket (Oecanthus fultoni) (orthsoc.org)
Riley’s tree cricket (Oecanthus rileyi) (orthsoc.org)
It is easy to identify species in photos if the middle option for Snowy is seen, and the first two options for Riley’s are seen, but compare the third options for both species…tricky. It is only the location of the black dot on the 2nd segment that differentiates the two species. Note how it is centrally placed on Snowy, and hugs the upper border on Riley’s. Camera angles and lack of clear photos of the edges of the segment makes it difficult to ID them at times.
You can see photos and a poster of most of the US species’ antennae here (I need to add Oecanthus beameri to the poster): Antennal Markings – TREE CRICKETS (oecanthinae.com)
FEBRUARY 3 – Colors
(Day 34)
Oecanthus tree crickets in the US are generally green, but have a variety of colors on their heads, abdomens and limbs. A few species do have a brown form – ranging from tan to dark brown.
Neoxabea bipunctata on the other hand, varies little in coloring. There are some darker individuals, and some with pinker tones, but the males are for the most part a pinkish tan color, and the females are white with large brown blotches. Unlike Oecanthus, Neoxabea males look very different from females.
Below are photos showing the variety of colors you can expect to find on tree crickets in the US.
Information on different pigments can be found in this abstract: (1) Pigments in Insects | Request PDF (researchgate.net)
This paper focuses on biochemistry and biosynthesis of pigments: (1) (PDF) Biochemistry and biosynthesis of insect pigments (researchgate.net)
FEBRUARY 2 – Stridulatory File and Teeth
(Day 33)
This is probably a good spot to remind y’all that I have very basic equipment (Canon camera and My First Lab microscope). 😉
This information from BB Fulton (s576lf15.pdf (orthsoc.org)) describes the anatomy and action of producing song:
stridulate, stridulation, stridulatory – BugGuide.Net
Check Figure 8 in this paper with excellent images of the stridulatory teeth: (1) (PDF) Micromorphological differentiation of left and right stridulatory apparatus in crickets (Orthoptera: Gryllidae) (researchgate.net)
SINA has several tables and charts showing the teeth totals and file lengths for different species.
Check out this abstract for an understanding of just how fast stridulation is occurring: https://doi.org/10.1111/evo.12668
One example: If the wings are opening and closing 60 times every second, and in doing so the scraper is striking 10 of the file’s teeth…that’s 600 teeth every second.
This photo below was taken by Carlos Gerardo Velazco-Macias of Neoxabea Mexicana: Neoxabea mexicana sp. nov. (Gryllidae: Oecanthinae): A new species from Mexico and a key for Neoxabea in North and Central America (pensoft.net)
Neoxabea mexicana has over 50 teeth….if only 20 of these teeth get scraped with each closing of the wing — that is 1200 teeth strikes per second !
FEBRUARY 1 – TEGMINA
(Day 32)
tegmen, tegmina – BugGuide.Net
The raised tegmina of a singing male tree cricket are undeniably beautiful. Some tree crickets do not sing, and have no or rudimentary tegmina. A heart shape forms on some genera that do raise their wings to sing. Below are photos of Oecanthus males in the U.S. The songs they produce will be covered in another month, but for now we will enjoy their romantic appearance. What female tree cricket could resist these showy hearts?
I looked at a number of articles with diagrams of the tegmina of male tree crickets, and came up with this:
That stridulatory file, responsible for the loud singing, is generally 0.8 to 1.8 mm in length (teeth and file will be covered tomorrow).
Although I do realize the geometry of a male tree cricket’s wing is responsible for the tones and volume of his song…I have a different view of why they look the way they do. It’s like the selfie feature on a phone. Since the female approaches the male from the back when mating, he needs to give her a view of how handsome he looks if she were viewing him from the front! With his tegmina raised, you can literally see a male tree cricket with his wings raised!
