Why you need to care about caterpillar control

With spring crops behind us and summer approaching, most of you are probably concentrating on the Big 3: thrips, aphids and whitefly. But recent alerts put out by the United States Department of Agriculture (USDA), bring a new emphasis to caterpillar control. Read on to understand what’s happening, how to control occasional pests like cabbage looper, and avoid potential issues at the border.

by Sarah Jandricic, Greenhouse Floriculture IPM Specialist, OMAFRA

As many of you might have heard from Flowers Canada, the USDA recently informed CFIA that the moth Chrysodeixis chalcites (known as tomato looper, or the golden twin spot moth) is an actionable pest in the U.S. This means they WILL take action on any shipments from Ontario they even suspect may contain this pest. Specifically, they may refuse or quarantine shipments, and/or increase inspections on shipments from Ontario.

So why does this matter to us? It’s a tomato pest, right?!?! Well…

The problem is two-fold. First, technically tomato looper can attack ornamental crops such as carnation and geranium, among others. But the bigger problem is that tomato looper looks just like a lot of other loopers (e.g. moths in the family Noctuidae)*. For example, both the larval and adult forms of tomato looper are pretty indistinguishable from cabbage looper (see pictures below), which commonly attacks certain ornamental crops, especially between July and September.

*(Basically all the moths in this family look like indistinguishable stupid brown blobs and their larvae are even worse to tell apart. I’m pretty sure Noctuidae means “Boring Blob Moth”, but I haven’t actually looked that up).

Looper adults

Tomato Looper (Chrysodeixis chalcites; left) is only slightly less ugly than the Cabbage Looper (Trichoplusia ni; right). Photos courtesy of Bugwood.org.

Unfortunately, the only way to accurately distinguish different looper species is by dissecting out the adult moth genitalia and comparing them (Yikes. I almost feel sorry for them; the people that have to do this I mean. Not the moths). This means that cases of mistaken identity at the border have the potential to occur, or shipments could be held until the identity of the culprit is confirmed.

Larvae of Tomato Looper (left) and Cabbage Looper (right) are extremely similar in appearance. DNA sequencing is the only way to accurately tell larvae apart. Photos courtesy of Bugwood.org.

Luckily, the solution to this problem is fairly straight forward: stay on top of your caterpillar control before you ship!

I’ve been in more than one floriculture operation where caterpillar control (even for Duponchelia) was a bit of an afterthought. But now, we should consider caterpillars more seriously in our pest control programs. If you’re diligent about your control program, they can be kept to low levels fairly easily.

Read more at ONfloriculture