One of the most commonly asked (and difficult to answer)
caterpillar questions is simply:

What's this caterpillar?!

 Got Lots? - Got Stung? - Is it Large? - Guides? - Have Photo? - Know Plant? - Rear it?

Return to Texas Entomology - Compiled by Mike Quinn

Moth vs. Butterfly Caterpillars

Note that the average caterpillar found in the wild is more likely a moth rather than a butterfly as there are approximately 4,700 species of moths in Texas but less than 500 species of Texas butterflies. Moth species outnumber butterflies in Texas by about 11 to 1. Not surprisingly, there is no comprehensive moth caterpillar field guide. The caterpillar stage of many moths is not known to science! The same goes for a few butterfly caterpillars.

However there is hope!!

Have a lot of Caterpillars?

If the caterpillar that you're wanting to identify is particularly abundant, then your local Ag. or Horticultural County Extension Agent may know what it is. 

When contacting anyone for caterpillar assistance, please include the following information:

  • Location - Very important to include at least the county where it was found.

  • Host Plant - Very helpful to note the plant the caterpillar was feeding on.

  • Date - Generally helpful to note the date (at least the month) when found

Texas County Extension Offices

Here are information links to a few species of caterpillars that have periodic outbreaks:

  • Juniper Budworm in Central Texas - Cudonigera houstonana (syn. Choristoneura)
                Photo - E.C. Knudson

  • Oak Leaf Tier - Croesia semipurpurana (Family Tortricidae)

  • Oak Leaf Roller - Archips semiferana (Family Tortricidae)

  • Saltmarsh Caterpillar - Estigmene acrea (Family Arctiidae) - Univ. of Florida

    • Mature Caterpillar - Common name is a misnomer as they are not tied to marshes 

    • Variably colored larvae usually are dark, but sometimes are yellowish brown or straw colored.

    • These caterpillars are active dispersers and are often found crossing the road.

    • They are most common in the southern United States, particularly the southwest.

    • Broadleaf weeds are the normal caterpillar food plants.

  • Tent Caterpillars - Malacosoma spp. (Family Lasiocampidae)

Stinging Caterpillars of Texas

 

Although many caterpillars have a threatening appearance, very few species are actually harmful to the touch. If your caterpillar did stung you, it should be listed among these links:

 

Is your caterpillar particularly large, 
bordering on humongous? 

If your caterpillar is humongous then it's likely one of the following two families:

  • Hornworm caterpillar - Family Sphingidae - members of this family have a distinctive  single stiff "horn" on the end of their abdomen

  • Silkworm caterpillar - Family Saturniidae. 

Hornworn Thumbnails

NE Texas

Central Texas

SE Texas

Rio Grande Valley

Butterfly and Moth Caterpillar Field Guides

Recently, there have been a number of excellent caterpillar filed guides published that may help:

Field Guides

Many new and used books can be found affordably through these links:
www.BookFinder.com // www.abebooks.com // www.alibris.com

Butterfly Caterpillars of North Texas

Dale Clark of Dallas County Lepidopterists' Society recently constructed 
a tremendous caterpillar ID site for the North Texas area:

Caterpillars of North Texas

Have a Photograph of your Caterpillar?

If you have (or can take) a digital photograph of your caterpillar, you can attempt to post it to BugGuide via the ID Request page. Once registered and logged in, look for the add image link.

As always, be sure to include the location, host and date of any caterpillar photograph.

Also, these folks work very hard to ID the many caterpillar (and other bug) images sent to them:

What's That Bug: Caterpillars and Cocoons 

Know What Plant the Caterpillar is Feeding on?

Now we're getting somewhere!!

Almost every butterfly and moth field guide has a list of caterpillar food plants listed in their index. In particular, see Scott (1986), Allen et al. (2005), or Wagner (2005) listed among the guides above.

If you don't have the above guides (or don't have them handy), try searching HOSTS - a database of the hostplants of the world's Lepidoptera. Enter the plant Family or Genus if know and restrict the location to USA. This database will return the scientific name of caterpillars known to feed on your host plant. (If you get a lot of hits, try entering the host species name to narrow down the options.) 

You can look up photos of the suggested caterpillar species in:

Rearing Information

If none of the above works, then the surest route to identification is to rear it through to the adult stage!! 

Rearing caterpillars can be a rewarding experience. Here are a few tips to get started. 

  • Provide a constant  supply of fresh caterpillar food plant. 
  • Maintain cleanliness by removing spoiled foliage and caterpillar droppings  (known as "frass"). 
  • Avoid high moisture situations that induce fungal growth. 
  • Avoid overcrowding. 
  • Don’t place the rearing container in direct sunlight. 
  • Do not disturb caterpillars in the process of molting or butterflies in the process of emerging.

Handle "spiny" or "hairy" caterpillars such as Asps with caution. Many of these are innocuous, but some have stiff hairs or "urticating" spines that can cause skin irritation or painful stings. Much detailed rearing information is available online:

If the adult insect that emerges from the pupal stage is a butterfly, you should be able to identify it from one or more butterfly field guides.  If the resulting insect is a moth, you might be able to identify if by looking through the plates of the Peterson moth guide:

If you have (or can take) a digital photograph of the moth, you can attempt to post it to BugGuide via the ID Request page. Once registered and logged in, look for the add image link.

Hope this helps!!

14 Oct 2009  ©  Mike Quinn / entomike@gmail.com / Texas Entomology