by Susan PostWalks along sunny paths in late spring woodlands are likely to yield a harvest of jewels. No, these cannot be collected and mounted in a ring; rather, they are emerald green tiger beetles, small but fierce denizens of the forest.
With the sun shining off its irisdescent blue-green elytra, the green tiger beetle resembles an emerald lost on a sandy path. A closer inspection usually reveals nothing—the "emerald" has flown several feet down the path.
Green tiger beetle adults are slender predatory beetles with long legs, large eyes, and thread-like antennae. Like all chewing insects they have a pair of mandibles. The tiger beetle's mandibles are sickle-shaped and very sharp pointed, with several teeth on the inner face. The name tiger beetle refers to its predaceous habits (both adults and larvae eat all kinds of insects) and to the ability of the adults to suddenly pounce on their prey.
During the summer months females will deposit their eggs in sandy soil. The eggs are deposited singly, each in a separate burrow. The larvae are whitish, S-shaped and grub-like with long curving jaws and a large hard head. The larvae prop themselves up in vertical burrows with their oddly shaped heads often plugging the entrance. They wait with open mandibles for a hapless victim, which they seize and take to the bottom of the burrow (sometimes a foot below the surface) to devour at their leisure. On the larva's 5th abdominal segment is a spine that anchors it to the side of the burrow. Thus, if a larva grabs an insect that is too large to overcome, it is anchored to the burrow and will not be pulled out.
The tiger beetle has 3 larval instars, that is, it sheds its exoskeleton three times in order to grow larger. Unlike most insects that just molt and go about their business, prior to each molt the tiger beetle larva must undertake an extra step and enlarge its burrow to accommodate its soon-to-be bulkier self. Pupation takes place in a chamber dug off the main tunnel and the entire life cycle will take up to 3 years.
For those lucky enough to catch one of these iridescent emeralds of the woods, be careful with this jewel of the beetle world for it is not merely ornamental. Tiger beetle mandibles, lethal to most small creatures, can inflict a very effective bite on unsuspecting fingers!
Wonderful article, thanks for the information? Are these beetles only found in the mid-west? I assume that since you are from Illinois and writing about them, that these are found there, but what about the east coast? Do I have a chance of finding a green tiger beetle in the D.C. area? I just know my son would enjoy going out on a hike to try and find one of these guys!
ReplyDeleteHi Richard,
DeleteMy name is Steve, I work for American Pest in Fulton, Maryland. I just identified one of these beauties, collected in Southern Maryland, close to Washington DC! So, yes! They do exists in this area, but with a 3 year life cycle, you will have to keep a sharp eye out for these insects. Cheers!
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ReplyDeleteThe tiger beetles are a widespread and diverse group. Hopefully, you and your son were able to find some while hiking in the woods.
ReplyDeleteI found one snacking on an ant on the AT in Virginia - so you should be able to find one.
ReplyDeleteI just found one in my yard in Lincoln, RI...looks just like the picture.
ReplyDeleteThey're all over the place outside of Boston.
ReplyDeletehttp://www.halereservation.org/
I have been seeing them in my garden in Southwestern Ontario. Glad to see an article with good pictures to help me identify them. I caught one and that is the only way i saw they had white spots. They are absolutely beautiful in the sun.
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