Female killer whales reach sexual maturity when they grow to about 15-18 feet (4.6 m-5.4 m) long, depending on geographic region. The gestation period for killer whales varies from 15-18 months. Birth may take place in any month--there is no distinct calving season. Calves are nursed for at least 1 year, and may be weaned between 1-2 years old. The birth rate for killer whales is not well understood, but, in some populations, is estimated as every 5 years for an average period of 25 years. Killer whales are highly social animals that occur primarily in relatively stable social groups that often range in size from 2 to 15 animals.
Other symptoms that alert you to a case of head lice include a ticklish feeling on your head, especially at night. The head louse is a nocturnal creature and is more active in the dark than during the light of day.
1 Itching. 2  Itching on the scalp, neck and ears is the most common symptom. 3  This is an allergic reaction to louse saliva. 4  When a person has an infestation for the first time, itching may not occur for two to six weeks after infestation. 5  Lice on scalp.