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Arachnid (Spider) Dichotomous Key - Spiders, Scorpions, Ticks and Mites



The Arachnid Insect Key relates various questions to an insect in an attempt to decipher its order for further identification.

Our seven point arachnid insect key can assist you in identifying an arachnid insect. Beginning with Question #1, determine which statement ('a' or 'b') is true for the insect in question. From there, simply follow the directions at the end of the true statement until you are ultimately given the name of the Order your insect belongs to. Finally, visit our list pages to specifically identify your insect.

Question 1.
a. Arachnid has a tail or a stinger - YES, go to Question #2
b. Arachnid has no tail or stinger - YES, go to Question #3

Question 2.
a. Tail is straight like a needle - YES, Order Uropygi (whipscorpions)
b. Tail curves with a stinger at the tip - YES, Order Scorpiones (scorpions)

Question 3.
a. Has large pedipalps (claws) - YES, go to Question #4
b. Lacks pedipalps (claws) - YES, go to Question #5

Question 4.
a. Arachnid is less than 5mm long and flat - YES, Order Pseudoscorpiones
b. Arachnid is 8-51mm long and "spider-like" - YES, Order Amblypygi (whipscorpions)

Question 5.
a. Arachnid has regular legs - YES, go to Question #6
b. Arachnid legs are thin/stilt-like w/ "high" knees & low body - YES, Order Opiliones (harvestmen)

Question 6.
a. Body is separated into a cephalothorax and abdomen - YES, go to Question #7
b. Body is oval-shaped and lacks a waist - YES, Order Acari (ticks and mites)

Question 7.
a. Has 7 segments on each leg & 1st pair are NOT longer than rest - YES, Order Araneae (spiders)
b. Has other number of segments on each leg & 1st pair ARE longer than rest - YES, Order Solifugae (windscorpions)