#Parasiteweek: Fly Attacks Caterpillar

August 12, 2016

Despite being the type of vegetable gardener who studies tomes on best practices, I have a hippy family that nurtures the welfare of tobacco hornworms (Manduca sexta). The big green caterpillars—considered major garden pests—feast and fatten like Henry VIII on the leaves, stems and fruit of the tomato plant. The caterpillars are masters of camouflage, blending into the dense, green foliage while clinging to the underside of leaves, and you often don't know that they're there until you spot their sizable dark droppings, the swift defoliation of your plant, or the mauled flesh of ripening tomatoes.

Caught in the act. Tobacco hornworm enjoying a black cherry tomato. Photo by: Candice Kim

You might consider the caterpillars, with their menacing red tail spike, unsympathetic garden inhabitants. The larvae, however, transform into the striking sphinx, or hawk, moth. Sphinx moths (family Sphingidae) are so large that species that hover while feeding on flower nectar have been mistaken for hummingbirds. Our local tobacco hornworms metamorphose into a mottled gray moth with an impressive four-plus-inches wingspan.

My family has raised numerous hornworms to their glorious adult form. Gently disengaged from our tomato plants, the caterpillars are given a new home in a small, pink-lidded terrarium, with a supply of fresh tomato plant branches and a moist bed of soil. Because they are mature caterpillars by the time we spot them and prepare their temporary plastic quarters, they are usually ready to pupate in the terrarium soil only a couple days after joining our household. Most have typically emerged weeks after pupating, but once we had a moth emerge ten months later. 

Our hand-raised sphinx moth, released after 10 months' pupation in a terrarium on top of the refrigerator. Photo by: Karen Klabin

Recently, I found a tobacco hornworm on the back of a tomato plant only because I could actually hear it in battle with a sarcophagid fly. The parasitic fly, unappealingly called a “flesh fly,” is ovoviviparous, meaning it deposits its progeny—maggots—in, among other places, the flesh of other creatures. The maggots then eat their way out of the reluctant host, thereby, in the case of the caterpillar, killing it (an event most gardeners would welcome). I watched the fly buzz and dart around the caterpillar, which squirted a dark liquid and twisted and seemingly snapped at the fly to try to keep it at bay. After a few minutes of battle, the dauntless fly landed successfully on the caterpillar, presumably depositing its larvae. I left the caterpillar on the tomato plant to fulfill its martyrdom as a maggot buffet.

The perp up close. The sarcophagid fly takes a break from attacking the hornworm. Photo by: Martin Schlageter

After returning from a short trip, I examined the tomato plant and failed to find the hornworm itself but did find the evidence of its diligent employ: a number of perfectly ripe tomatoes marred by gnawed and moldy flesh. The tomatoes weren't salvageable. And so the thought of the hornworm being parasitized by the sarcophagid fly did not break my heart. Nor those of my hens, who enjoyed the ruined tomatoes.

The ladies enjoying a hornworm-ravaged tomato. Photo by: Karen Klabin

(Posted by: Karen Klabin)


First Clouded Sulphur Butterfly Pupa in North Campus

February 23, 2012

Last week, Jany Alvarez, one of the Museum's Guest Relations staff, was sitting at the bus stop adjacent to the North Campus. While she was waiting for her bus, she saw an interesting sighta caterpillar crawling along the sidewalk! Thinking that the caterpillar would be better off on a plant than on the cement, she picked the caterpillar up and placed it carefully on a Dudleya plant on the Living Wall. Later that day, another Guest Relations staffer watched the caterpillar pupate! By the time word travelled to me, the pupa looked like this:

Yellow pupa on DudleyaWhen I came into work on Tuesday morning, the pupa had changed color! I took more pictures and went back to my office to identify it.

Close up of pupa. Note the small horn-like structureThe pupa belongs to a butterfly regularly seen in and around Los Angeles, the Cloudless Sulphur, Phoebis sennae. The Cloudless Sulphur belongs to the Pieridae butterfly family, which includes White, Sulphur, and Orange-tip butterflies. The most common butterfly in this family is the Cabbage White, which flies year round in our area and is a pest on vegetables such as cabbage, kale, and broccoli. In contrast the caterpillar of the Cloudless Sulphur feeds on cassia plants (genus Senna) and is often seen in our local deserts where the two California native species in this genus grow naturally. The altered nature of Los Angeles is such that non-native cassias are now common all over our area. They've been planted in various places like your neighbor's backyard, your local park, and even in the North Campus. The bus stop where Jany found the Cloudless Sulphur caterpillar is only 20 feet away from a few feathery cassias, Senna artemisioides, which were recently planted in the North Campus!I guess our premise for developing habitat around the Museum is correctplant it and they will come!

Male Cloudless Sulphur from our Entomology Collection

(Posted by: Lila Higgins)

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The Twelve Days of Christmas

December 23, 2011

On the Twelfth Day of Christmas the North Campus gave to me...

Twelve skippers skipping


Eleven pill bugs pillaging

On the Twelfth Day of Christmas the North Campus gave to me...

Twelve skippers skipping



Eleven pill bugs pillaging





Ten fritillaries a-feeding





 Nine gulls a-diving (dumpster diving that is)





Eight mantids a-milking





Seven caterpillars a-crawling






Six ladybugs a-laying



Five phorid (fly) wings





Four calling crows





Three French hummingbirds





Two turtle fox squirrels





 And an oak gall in an oak tree!







Wishing you a happy holiday season!



(Posted by: Lila Higgins)


North Campus Monarchs

October 13, 2011

Yesterday afternoon myself and number of other staff members braved the heat to continue our survey of North Campus insects. On the heels of last week's Gulf Fritillary discovery, I found the site's first Monarch butterfly caterpillar, Danaus plexippus!


Monarch butterfly caterpillar


As soon as I saw the caterpillar I knew it was a Monarch: There isn't another caterpillar in our area with such yellow, black, and white banding. Also, the caterpillar was found on a narrow-leaved milkweed plant, Asclepias fascicularis, which is one of the food plants of this well-known species.


Based on its size, this caterpillar is in the second to last caterpillar stage (4th instar). Over the coming weeks it will molt to the last and final stage (5th instar), and then turn into a chrysalis.  In time for its fall migration, the adult Monarch will emerge and make its way to an overwintering site somewhere along the coast.

In the coming years I hope to tag and track the adult Monarchs that emerge in the North Campus, so we can determine the exact location(s) of our Monarchs' overwintering site(s). Tagging Monarchs is an easy process that in no way hurts the butterflies. The adults are collected with a net and then carefully held while a small sticker (approximately 2% of the butterflies weight) is attached to the hind wing of the butterfly. The butterfly is then released and flies onto its overwintering site. When the Monarchs dies the following spring (after mating) the tags are hopefully retrieved and we can answer the question, where do our North Campus Monarchs overwinter?


Demonstrating how to handle a Monarch for tagging



(Posted by: Lila Higgins)