Third stage larvas are about 900 microns long and appear 10-20 days after infecting the mosquito in less than 4 weeks. The 3rd stage juveniles migrate to the mouthparts of the moquito. Infection of dogs occurs while mosquitoes are feeding. Third stage juveniles escape onto the skin and enter it through the feeding site wound.

For about 80 days, juveniles are in the subcutaneous tissues and muscles where the 3rd molt takes place 9-12 days after entry. In the tissues. The 4^th stage juveniles attain lengths up to 25 mm. They begin entering the right side of the heart shortly after the 4th molt 60-70 days after infection.

During the mosquito’s blood meal, the 3rd stage larvas are deposited on the skin and enter the host by the bite wound. These larvas molt to the 4^th stage and migrate to the dog's abdomen. In several months, they invade the chambers of the heart and the pulmonary arteries.

Development to maturity with males 14-19 cm long and females 23-31 cm takes 175-225 days, at which time mfs appear in the blood. The reproductive period may pass 5 years.