Ticks 101
Developmental Stages of Ticks
Anatomy of Hard and Soft Ticks
Photo showing life cycle of a tick from Eggs, Larva, Nymph to Adult Female or Male.
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Developmental Stages of Ticks
The life cycle of ticks includes four stages: egg, six-legged larva, eight-legged nymph, and adult.

The Egg
Mating of hard ticks usually occurs while they are on the host animal. Afterwards the female drops to the ground and, after a brief pre-oviposition period of three to 10 days, begins to deposit eggs on or near the earth. The female hard tick feeds once, lays one large batch of eggs sometimes numbering in the thousands, and dies. Most of the soft ticks engorge with blood several times and deposit about 20 to 50 eggs in a batch after each blood meal. Eggs hatch in two weeks to several months, depending upon temperature, humidity and other environmental factors.

The Larva
The larvae, or "seed ticks," have only six legs, and the sexes are indistinguishable. Their chances of attaching to a host are precarious, sometimes resulting in prolonged fasts.

Despite tolerance to starvation, a very high percentage die. Some individuals climb on vegetation, waiting for a small rodent to pass within reach. Some actively seek a vertebrate host, being guided by the scent of the animal. After a blood meal, the engorged larvae usually drop to the soil and molt to the eight-legged nymph stage. The larvae of one-host ticks remain on the host to molt.

The Nymph
The nymph has eight legs like the adult but has no genital opening. This stage also must undergo a critical waiting period for a suitable host. After engorgement, the nymph drops from the host, molts, and becomes an adult. Nymphs may rest for long periods before becoming adults. Some species of hard ticks live less than one year while others live three yearsor more. Each time a tick leaves its host it risks its survival on on finding another host. Some species have the advantage of molting on the host. For example, the cattle tick is a one-host tick. Multiple-host tick species are able to exist because of their great reproductive capacity and their ability to survive for a long time without food.

Hard ticks have only one nymphal instar, the nymph becoming an adult after molting. Soft ticks may have several nymphal instars.

The Adult
Typically, the nymph molts after engorgement and becomes an adult. Sex then is distinguishable for the first time as the female hard tick differs from the male in having a small scutum. The sex of soft ticks may be determined by the shape of the genital opening located between the second pair of legs. In male soft ticks the genital opening is almost circular, while it is oval and definitely broader than long in female specimens. Unlike mosquitoes, both male and female hard ticks are blood suckers, and both require several days feeding before copulation. After the male hard tick becomes engorged, he usually copulates with one or more females and then dies. Following copulation, the female tick drops to the ground. The eggs require several days to develop. Then she begins oviposition. After a few more days, her life's mission accomplished, the spent female hard tick also dies. The female soft tick may lay several small batches of eggs but she requires another blood meal before each episode of oviposition.

For more information, contact your local health department,
or the Texas Department of State Health Services.