A phylogenetic study by Jost & Shaw in 2006 using sequences from 18S, 28S, and 16S rRNA supported the monophyly of Ensifera. Most ensiferan families were also found to be monophyletic, and the superfamily Gryllacridoidea was found to include Stenopelmatidae, Anostostomatidae, Gryllacrididae and Lezina. Schizodactylidae and Grylloidea were shown to be sister taxa, and Rhaphidophoridae and Tettigoniidae were found to be more closely related to Grylloidea than had previously been thought. The authors stated that "a high degree of conflict exists between the molecular and morphological data, possibly indicating that much homoplasy is present in Ensifera, particularly in acoustic structures." They considered that tegmen stridulation and tibial tympanae are ancestral to Ensifera and have been lost on multiple occasions, especially within the Gryllidae.
Crickets are hemimetabolic insects, whose lifecycle consists of an egg stage, a larval or nymph stage that increasingly resembles the adult form as the nymph grows, and an adult stage. The egg hatches into a nymph about the size of a fruit fly. This passes through about 10 larval stages, and with each successive moult, it becomes more like an adult. After the final moult, the genitalia and wings are fully developed, but a period of maturation is needed before the cricket is ready to breed.
Gryllus firmus exhibits wing polymorphism; some individuals have fully functional, long hind wings and others have short wings and cannot fly. The short-winged females have smaller flight muscles, greater ovarian development, and produce more eggs, so the polymorphism adapts the cricket for either dispersal or reproduction. In some long-winged individuals, the flight muscles deteriorate during adulthood and the insect's reproductive capabilities improve.
The decision to attempt a run is ideally made by the batsman who has the better view of the ball's progress, and this is communicated by calling: usually "yes", "no" or "wait". More than one run can be scored from a single hit: hits worth one to three runs are common, but the size of the field is such that it is usually difficult to run four or more. To compensate for this, hits that reach the boundary of the field are automatically awarded four runs if the ball touches the ground en route to the boundary or six runs if the ball clears the boundary without touching the ground within the boundary. In these cases the batsmen do not need to run. Hits for five are unusual and generally rely on the help of "overthrows" by a fielder returning the ball. If an odd number of runs is scored by the striker, the two batsmen have changed ends, and the one who was non-striker is now the striker. Only the striker can score individual runs, but all runs are added to the team's total.
In a two-innings-a-side match, one team's combined first and second innings total may be less than the other side's first innings total. The team with the greater score is then said to have "won by an innings and n runs", and does not need to bat again: n is the difference between the two teams' aggregate scores. If the team batting last is all out, and both sides have scored the same number of runs, then the match is a tie; this result is quite rare in matches of two innings a side with only 62 happening in first-class matches from the earliest known instance in 1741 until January 2017. In the traditional form of the game, if the time allotted for the match expires before either side can win, then the game is declared a draw.
The fly Ormia ochracea has very acute hearing and targets calling male crickets. It locates its prey by ear and then lays its eggs nearby. The developing larvae burrow inside any crickets with which they come in contact and in the course of a week or so, devour what remains of the host before pupating. In Florida, the parasitic flies were only present in the autumn, and at that time of year, the males sang less but for longer periods. A trade-off exists for the male between attracting females and being parasitized.
Crickets are small to medium-sized insects with mostly cylindrical, somewhat vertically flattened bodies. The head is spherical with long slender antennae arising from cone-shaped scapes (first segments) and just behind these are two large compound eyes. On the forehead are three ocelli (simple eyes). The pronotum (first thoracic segment) is trapezoidal in shape, robust, and well-sclerotinized. It is smooth and has neither dorsal or lateral keels (ridges).
Crickets have many natural enemies and are subject to various pathogens and parasites. They are eaten by large numbers of vertebrate and invertebrate predators and their hard parts are often found during the examination of animal intestines. Mediterranean house geckos (Hemidactylus turcicus) have learned that although a calling decorated cricket (Gryllodes supplicans) may be safely positioned in an out-of-reach burrow, female crickets attracted to the call can be intercepted and eaten.
Subject to certain variations, on-field clothing generally includes a collared shirt with short or long sleeves; long trousers; woolen pullover (if needed); cricket cap (for fielding) or a safety helmet; and spiked shoes or boots to increase traction. The kit is traditionally all white and this remains the case in Test and first-class cricket but, in limited overs cricket, team colours are worn instead.