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| Photo provided by D. Schimpf |
In the Duluth area, we may expect larvae to hatch starting in June and July, depending on when they were laid. So, we hope that we will soon begin to document finding larvae in our active tick collection activities.
However, larvae are exceptionally tiny and very hard to see with the naked eye. Fortunately, we do not believe they pose much risk for disease transmission, particularly as Lyme causing bacteria are not thought to be passed from the female to eggs.
If you do happen to see a larva, and you have a magnifying glass or very good eyesight, you may notice that they only have six legs. This is a curious fact, as ticks are a member of the class Arachnida, which means they are not true insects. They are more closely related to spiders, than say mosquitos, and would be expected to have eight legs.
In this photo, we have three larval ticks. The green lines in the background form 1mm squares, so you can get a sense of just how tiny they are. The far left is a Dermacentor variabilis, or wood tick/dog tick. You can tell by the little lines on the bottom end of the tick body. These are called festoons, and are not present on Ixodes scapularis ticks. The tick in the middle is an Ixodes, and you can clearly see that it only has three legs on the left side (likely one of the legs on the right broke off during collection). The larger larva on the right is engorged from feeding, it was pulled from a migrating White-throated Sparrow captured at Hawk Ridge in autumn 2019.
Had these ticks not been caught and used for scientific purposes, if they were able to successfully feed, they would then molt and become a nymph. Emerging from their first molt, they would gain two more legs for the arachnid class standard of eight legs. From there they would look to feed again in order to molt (retaining their eight leg status) one last time into adults, completing their life cycle.
-C. Fisher
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