On a recent stroll down a pathway in my neighbourhood, I was startled with an unexpected – and, for me, completely unfamiliar – sight:  the incredibly ambitious nests of Archips cerasivorana (uglynest caterpillars).   An elaborate network of silk netting covered every single branch of the critters’ leafy hotels and spread from plant to plant in dense cobwebs, like  Hallowe’en decorations set out at the wrong time.  Completely sheltered in their cosy nests, the caterpillars were settled down to a grand old feast.

Having absolutely no experience with uglynest caterpillars, I initially feared that this was evidence of either western tent caterpillars (Malacosoma californicum) or forest tent caterpillars (Malacosoma disstria) but I knew that my guess was inaccurate as soon as I saw the creatures themselves.   Uglynest caterpillars are yellow-green in colour, with a dark head –  not the types I’m used to.   As well, tent caterpillars are so named because when they infest an area, they create many, many tent-shaped webs, and they don’t tend to do things on a localized level like uglynest caterpillars do.  Tent caterpillars are more of a “widespread outbreak” pest, if you know what I mean!

Apparently, uglynest caterpillars don’t usually kill their host plants – although if the plant is already weak, defoliation may just do it in completely.   The nests can be hosed down with a high pressure water system; there is no need to apply an insecticide.  The caterpillars will feed and move on through their growth stages, eventually reaching adulthood as small, pale brown moths.  For me, this was a real insight into the sheer industriousness of insects!

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If you’re looking for an easy-to-use “bug I.D.” book for the Prairies, look no further than Nora Bryan and Ruth Staal’s The Prairie Gardener’s Book of Bugs:  A Guide to Living with Common Garden Insects (2003, Fifth House Ltd.).  It is compact and well-written, and the illustrations by Grace Buzik are amazing.