Saturday, 4 October 2014

One Big Honking Sawfly!  

This has been a good year for finding some unusual bugs here in Nova Scotia. As one example, this year I encountered and photographed both male and female, and for the second time, the larva (shown here, photographed at the Pockwock Watershed lands on September 28th) of the Elm Sawfly, Cimbex americana. To be succinct, this is one big honking sawfly!

This is the adult male Elm Sawfly, photographed at McIntosh Run in Spryfield on July 10th. These large relatives of bees, wasps and ants, are about the same size as large bumble bees, and when one flies past your head, you know it.

Here's the adult female Elm Sawfly, photographed on a cool, cloudy day at Roaches Pond in Spryfield on July 29th. The abdomen can also be black or brick red/orange but the legs and antennae are always bright yellow.

The first time I encountered the larva of the Elm Sawfly was at Dollar Lake on August 8th, 2012. These large caterpillar-like larvae are about 50 mm or 2 in. long, have obvious simple eyes (ocelli), three "true" legs and six or more prolegs—moth and butterfly caterpillars have 5 or fewer prolegs and multiple ocelli that are usually not at all obvious.

Like my most recent encounter with Elm Sawfly larvae, this one is feeding on willow, though why it would choose to feed on the twig rather than the leaf is a mystery. The spiral body shape necessary to feed on the twig puzzled me for quite some time before I finally figured out it was a sawfly larva and not a caterpillar.