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).[3]
Some species of cricket are polyandrous. In Gryllus bimaculatus, the females select and mate with multiple viable sperm donors, preferring novel mates.[21] Female Teleogryllus oceanicus crickets from natural populations similarly mate and store sperm from multiple males.[22] Female crickets exert a postcopulatory fertilization bias in favour of unrelated males to avoid the genetic consequences of inbreeding. Fertilization bias depends on the control of sperm transport to the sperm storage organs. The inhibition of sperm storage by female crickets can act as a form of cryptic female choice to avoid the severe negative effects of inbreeding.[23] Controlled-breeding experiments with the cricket Gryllus firmus demonstrated inbreeding depression, as nymphal weight and early fecundity declined substantially over the generations'[24] this was caused as expected by an increased frequency of homozygous combinations of deleterious recessive alleles.[24][25]
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.[4] 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.[17]
Additional runs can be gained by the batting team as extras (called "sundries" in Australia) due to errors made by the fielding side. This is achieved in four ways: no-ball, a penalty of one extra conceded by the bowler if he breaks the rules;[108] wide, a penalty of one extra conceded by the bowler if he bowls so that the ball is out of the batsman's reach;[109] bye, an extra awarded if the batsman misses the ball and it goes past the wicket-keeper and gives the batsmen time to run in the conventional way;[110] leg bye, as for a bye except that the ball has hit the batsman's body, though not his bat.[110] If the bowler has conceded a no-ball or a wide, his team incurs an additional penalty because that ball (i.e., delivery) has to be bowled again and hence the batting side has the opportunity to score more runs from this extra ball.[108][109]

Several types of cricket songs are in the repertoire of some species. The calling song attracts females and repels other males, and is fairly loud. The courting song is used when a female cricket is near and encourages her to mate with the caller. A triumphal song is produced for a brief period after a successful mating, and may reinforce the mating bond to encourage the female to lay some eggs rather than find another male.[6] An aggressive song is triggered by contact chemoreceptors on the antennae that detect the presence of another male cricket.[7]
The game underwent major development in the 18th century to become England's national sport.[citation needed] Its success was underwritten by the twin necessities of patronage and betting.[34] Cricket was prominent in London as early as 1707 and, in the middle years of the century, large crowds flocked to matches on the Artillery Ground in Finsbury.[citation needed] The single wicket form of the sport attracted huge crowds and wagers to match, its popularity peaking in the 1748 season.[35] Bowling underwent an evolution around 1760 when bowlers began to pitch the ball instead of rolling or skimming it towards the batsman. This caused a revolution in bat design because, to deal with the bouncing ball, it was necessary to introduce the modern straight bat in place of the old "hockey stick" shape.[36][citation needed]
The wicket-keeper and the batsmen wear protective gear because of the hardness of the ball, which can be delivered at speeds of more than 145 kilometres per hour (90 mph) and presents a major health and safety concern. Protective clothing includes pads (designed to protect the knees and shins), batting gloves or wicket-keeper's gloves for the hands, a safety helmet for the head and a box for male players inside the trousers (to protect the crotch area).[80] Some batsmen wear additional padding inside their shirts and trousers such as thigh pads, arm pads, rib protectors and shoulder pads. The only fielders allowed to wear protective gear are those in positions very close to the batsman (i.e., if they are alongside or in front of him), but they cannot wear gloves or external leg guards.[73]

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.[20]

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.[81]