Life of the No-See-Um: the Cacao Tree Pollinator

The no-see-um is a fascinating benthic macroinvertebrate that goes througha complete metamorphosis, involving the complete four stages of the lifecycle; egg, larval, pupal, and adult phase. Being less than 3mm long in theiradult phase they have rightfully earned their name as no-see-ums. Today wewill explore what happens after the no-see-um pupae leaves the safety andfamiliarity of the water. And how does the no-see-um pupae transform into its adult form? To explore these questions, we’ll start at the very beginning-- when the no-see-um eggs are first laid.

An adult female no-see-um will lay as many as 450 eggs per batch and can lay up to as many as 7 batches of eggs during her lifetime. Eggs will typically hatch within 2 to 10 days along banksides and atop rocks within the water or even on aquatic vegetation. The amount of time it will take for development varies by species and is dependent of water temperatures and other environmental conditions.

Once hatched the larval stage begins and no-see-ums will go through four stages of development, also known as instars. The no-see-um larvae will develop out of the water along moist environments that include the stream bank and wet sand or mud.

No-see-ums will then pupate underwater where they will use specialized structures called respiratory horns emerging just above the water surface which allows the no-see-um to breathe and remain close to the water surface. This stage of development can last anywhere from 2 to 3 days and the coloration of the no-see-ums can vary from light yellow to dark brown.

In its adult form, no-see-ums are grey in colour and have wings that are patterned and covered in hairs. Mating occurs when adult no-see-ums swarm in large numbers in flight. Female no-see-ums will fly into these swarms where copulation occurs mid-air. Female no-see-ums will then go hunting for a blood meal and prey upon animals, including humans in order to obtain the nourishment needed to lay her eggs. Much like blackflies, no-see-um adults are attracted to lactic acid, carbon dioxide and strong perfumed odors. The complete cycle of a no-see-um can occur in 2 to 6 weeks or alternatively it can take up to a year. Again, life cycle stages and the period of development within each stage is heavily dependent on species type.

Fun Fact: No-see-ums have even been found on Mount Everest!

Interested in learning more about benthic macroinvertebrates and how they can be used to measure the health of rivers and streams?Be sure to follow EcoSpark’s social media to stay updated on our Changing Currents program and our other citizen science andenvironmental education programs.

References

• Elements for Life. (2018). All about Cacao- The Origins of Chocolate. Retrieved from: https://www.elementsforlife.co.uk/pages/all-about-cacao-the-origins-of-chocolate
  

Carina holds a Bachelor of Honors in Environmental Studies and a diploma in Ecosystem Technology, both of which developed her interest in using geographic information systems to communicate about complex issues, such as climate change. In her role as Lead Environmental Educator, Carina designs geospatial education tools for EcoSpark’s citizen science programs. When outdoors in the field, you will often find her streamside identifying aquatic critters, communicating her enthusiasm for the outdoors, and demonstrating her dedication to stewardship practices with youth and adults throughout the GTA.