Do insects have a circulatory system?

Hint: The circulation of blood by the network of organs throughout the body is also called the vascular system. The important function of the circulatory system is to transport blood throughout the body, which is essential for our body because it carries different nutrients, oxygen, carbon dioxide, blood cells, different hormones, that help in the development or growth and nourishment in the cells of every organ.

Complete Answer-
Insecta is the largest class of animals including more than 750,000 species. Insects are the most successful land invertebrate and belong to the phylum Arthropods which is the largest phylum of the animal kingdom. The insect body is divisible into three regions- head, thorax and abdomen.
Yes, they have an open type of circulatory system. The blood is pumped by the heart, which passes through large vessels into open spaces or body cavities called lacunae or sinuses. Body tissues are in direct contact with blood. Blood flows at very low pressure through lacunae or sinuses. Blood flows in the haemocoel (body cavity) instead of blood vessels. The blood called hemolymph is colourless and contains white corpuscles. Exchange of different materials through blood and body cells is direct in contact and very slow and less efficient. The volume of flow of blood is not regulated.

Note:
Circulatory patterns are of two types- open and closed. The open circulatory system are mainly found in the arthropods (prawns, crabs, insects, spiders, etc.), annelids (leech), protochordates, etc. while closed circulatory system is found in annelids (earthworms, neries), vertebrates, echinoderms, etc.