When killed, some mosquitoes bleed and some do not. Why?

 There are more than 1,200 species of mosquitoes but all of them do not feed on the blood of mammals. The three important blood feeders found throughout the world are Culex, Anopheles and Aides. Even in these species, only the female mosquitoes suck blood, while the males thrive on plant sap and honey from flowers. The blood when drawn enters the highly dilatable stomach of the female which uses it for reproductive purposes. At least one-fifth of a drop of blood is sucked at a time. If these female mosquitoes are killed, they bleed.  Unfed females and males do not bleed when killed.