This insect is trying to pretend it is a bee or wasp.
Sara wasn’t fooled, however. It is actually a beetle called the locust borer, Megacyllene robiniae.The adults are very commonly found feeding on goldenrod in the fall where black locusts grow.
The adult beetles lay their eggs in the wood of the black locust tree. The larvae tunnel through the wood, eating it.
Note:Â If you see a beetle that looks like this in the spring, it just might be a hickory borer instead.
Our featured insect can be quite difficult to spot on a plant.
Do you see the insect? I’ll give you a hint: The head is covered.
You can see why it is called a tortoise beetle. In fact, it is the thistle tortoise beetle, Cassida rubiginosa.
The thistle tortoise beetle has an interesting history. It was introduced into North America because it feeds on a weed that was accidentally introduced earlier, the “Canada” thistle. By the way, the “Canada” thistle is actually from Europe, where it is called the creeping thistle. Shows you how misleading common names can be! In any case, the thistle tortoise beetle is an insect that was purposely brought in for weed control.
The larvae of this species (see BugGuide) carry debris and feces on their backs to discourage predators. Wish I had found one of those.
These photographs were taken in western New York.
Have you ever seen a tortoise beetle? Was it green like this one?
Ever seen asparagus growing “wild”? I found some in a field in western New York.
It had some insect larvae on it. Are they caterpillars? Are they sawflies?
Some were smaller than others.
Here is a clue. Check out this bright orange beetle. It is the spotted asparagus beetle, Crioceris duodecimpunctata.
Yes, it is a spotted asparagus beetle larva.
If you look closely, you can even spot some eggs.
It is unusual to see so many life stages of a single insect on one plant. When it is mature, the larva drops off and forms the pupa in the soil nearby, so none of the life stages move very far from the asparagus plant.
The adult insects are bright red and black, which is a warning coloration.
They also have another trick. Have you ever picked up a spotted asparagus beetle? They stridulate or make sounds to defend themselves when captured.
If you are looking for an insect that is abundant locally for studying insect life cycles, you might want to check into asparagus beetles.
For more information, see Roberta Gibson Writes.
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