I found this good info about their life cycle
There have been several studies on the developmental biology of the tomato russet mite with varying results. Bailey and Keifer (1943) observed that at 21 degrees C, the tomato russet mite female laid an average of 15 eggs in her lifetime. Newly emerged females began laying eggs after 2 days. Eggs hatched in 2 days at room temperature, the larval stage was only 1 day, and the nymphal stage lasted 2 days. Rice and Strong (1962) reported that the life cycle was 6.5 days under optimal conditions (21 degrees C (70 degrees F) and 30% relative humidity) and under very high temperatures (32 degrees C (90 degrees F)), lower humidities were necessary for survival. This is contradictory to previous results by Planes (1941). He noted that high humidity contributed to the rise of high tomato russet mite populations.
Rice and Strong (1962) reported higher reproductive rates than previous experiments. Their study found that female tomato russet mites laid 10 to 53 eggs, depending on the environmental conditions. Longevity of the females was 47.5 days at 21 degrees C (70 degrees F) and 90% relative humidity. Their result indicated that the optimum conditions for population increase was temperatures near 26.7 degrees C (80 degrees F) and 30% relative humidity.
A study by Tsalev (1967) indicated that tomato russet mites have high developmental rates in relatively cool conditions (15-24 degrees C (59-75 degrees F)) and 70-80% relative humidity. A single generation developed in 15 to 18 days.
The developmental biology information in the following sections is based on a 1979 study by Abou-Awad. The results were based on experimental conditions of 25 degrees C (77 degrees F) and 70% relative humidity. Males developed in an average of 4.62 days and females developed in an average of 5.15 days.
Eggs
Eggs are round and colorless to white (Kay, 1986). The eggs are laid on leaves and stems of plants. Both males and females hatch in 2.3 days.
Larvae
The larval stage or first nymphal stage lasts about 11 hours for females and about 7 hours for males. The larval chrysalis (quiescent molting period between stages) lasts about 13 hours for both males and females. Larvae are white in color and look similar to the adults, but they are smaller and less active.
Nymph
The nymphal stage or second nymphal stage lasts a little over a day for females and about 19 hours for males. The nymphal chrysalis lasts 18 hours for females and 16 hours for males.
Adults
The adults are about 0.15 to 0.2 mm long and 0.05 mm wide (Kay, 1986). Their bodies are torpedo-shaped and cream to light gray-brown in color. Females live for about 22 days and males live for an average of 16 days. Females have a preovipositional period of 2 days and an ovipositional period of 19 days. The female produces an average of 16 eggs during the ovipositional period. Offspring of both sexes are produced by fertilized females. Unfertilized females only produce males.
more here
http://www.extento.hawaii.edu/kbase/crop/type/a_lycope.htm