What is the primary function of the proboscis in mosquitoes?

The primary function of the proboscis in mosquitoes is to pierce skin and consume blood. The proboscis is a specialized mouthpart that is long and slender, allowing it to reach blood vessels beneath the skin of its host. When a female mosquito bites, she uses her proboscis to penetrate the skin, while also injecting saliva that contains anticoagulants to prevent the blood from clotting, which facilitates feeding. This adaptation is essential for her reproductive success, as the nutrients obtained from the blood are needed for the development of her eggs.

While other choices mention functions related to different activities, they do not pertain to the primary role of the proboscis in relation to mosquitoes. For example, injecting venom is characteristic of other insects, such as some spiders or wasps, not mosquitoes. Sucking nectar is an activity performed by some, but mosquitoes primarily feed on blood, particularly females that require protein for egg development. Laying eggs is a reproductive function that does not involve the proboscis at all, further emphasizing that the correct answer focuses specifically on the blood-feeding mechanism enabled by the structure of the proboscis.