Meet the Slugs – Red-crossed Button Slug

Red-crossed Button Slug - Limacodidae - Tortricidia-pallida (4653), Millstream Gardens Conservation Area, MO
Red-crossed Button Slug – Limacodidae – Tortricidia-pallida (4653), Millstream Gardens Conservation Area, MO

The next slug to make your acquaintance is the Red-crossed Button Slug.  This species is quite similar to one or two others as both larvae and adult, but given that most lists I have seen from Missouri list this one and not the others, I am pretty confident in this ID.  This species lacks the stinging, protective hairs, going instead with a more camouflage approach of looking like a bit of leaf blight as it passes over leaves of oaks, hickories and quite a few other known woody, deciduous host plants.

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On a trail of silk – Red-crossed Button Slug – Limacodidae – Tortricidia-pallida (4653), Hickory Canyon Natural Area

The image above gives a glimpse into how the slugs get around – on a substance described as liquid silk.  See the winding trails?

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Even their frass is distinctive – Red-crossed Button Slug – Limacodidae – Tortricidia-pallida (4653), Hickory Canyon Natural Area

Here I caught one in the act.  From what I’ve read, slugs leave distinctively shaped (indented) frass that is different from that of other caterpillars.  I didn’t pause long enough to investigate.

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The slug moth – Red-crossed Button Slug – Limacodidae – Tortricidia-pallida (4653), Hickory Canyon Natural Area

Finally, the adult slug moth is pictured above.  Slug moths are strongly attracted to lights and, from what I have read, are often some of the first species to show up when setting up a light and sheet/trap.  I have a theory that this may be why I find many less slug caterpillars the closer I look near St. Louis.  Although I found very similar habitats with the same composition and numbers of sapling oaks and hickories (the favored host plants), the closer I came to the city the number of slug caterpillars dropped significantly.  Perhaps the city lights are sucking in the adults before they are able to reproduce?  Probably a too simplistic idea, but it is a trend I noticed.  It could just as well be due to fragmented habitat and overall less habitat available the closer one gets to the city.

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One thought on “Meet the Slugs – Red-crossed Button Slug

  1. Excellent. I’m sure I’ve seen the “liquid silk” trails before, but never questioned composition, much less source. Overlooking too much.

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