Beware fuzzy caterpillars!

We have planted many hundreds of trees and shrubs on our property to encourage wildlife of all sorts, so I keep a careful eye out for pests that eat these plants. Some of the worse problems are due to insects that come in groups, such as caterpillars of various moths. I am used to dealing with army worms and web worms but came across a new enemy recently. Groups of hungry caterpillars appeared on our treasured black walnut trees (and sumac also) and started a full-scale attack (see photo above). In their young stage they were white with black spots and a black head, and were quite hairy. Now a fuzzy caterpillar often means "KEEP AWAY" since the hairs can be irritating and even toxic. These turned out to be hickory tussock moths or hickory tiger moths which are well known to possess stinging hairs and even to be toxic for birds to eat. They group together, likely with their siblings that hatched from their mother's eggs, and remain together for some time until they get much larger when they live alone (see photo below, of a much older caterpillar from our yard- not a typical coloration- often they are more black and white).

It is interesting to think about why not only insects but many types of animals group together in flocks or swarms. It is usually considered to be a defense, potentially to confuse and divert the attack of predators. In the case of these caterpillars, it is also likely that distasteful and/or toxic

creatures

ban together with siblings to gain an additional advantage if a predator does attack and learns to avoid this color pattern in the future. Siblings that share many of the same genes will benefit more by being together with their brothers and sisters than with strangers, if they are attacked and some are sacrificed to teach the predator to avoid the others.

Caterpillars have a variety of defenses other than stinging hairs and toxic flesh. They tend to be active at night and group together in daytime under protective webs. When I touched the leaf on which the young hickory tussock moths were sitting, a surprising thing happened- numbers of caterpillars began to drop down to the ground quickly on web lines (see photo). You might wonder why this would be necessary when these caterpillars seem to be so well protected. However virtually all good defenses have spawned a specialized predator that can circumvent the defensive strategy- in this case it is the yellow-billed cuckoo (see photo) which is a fuzzy caterpillar eater. Not

coincidentally

we have noticed far more cuckoos on our property this year than last when caterpillars were not so numerous. So the hickory tussock moth caterpillars drop from the tree at the

slightest

indication of a cuckoo being present, and can then crawl back into the tree after the cuckoo leaves.

The intricate natural history of something so seemingly inconsequential as a tiger moth caterpillar tells us once again that the adaptations of this larval moth are subject to very specific design criteria to maximize its chances of survival and subsequent reproduction. So even if we destroy some of these creatures that eat our yard plants, we cannot fail to marvel at their remarkable methods of existence.

Bill

Dunson

Galax

, VA &

Englewood

, FL

Beware the red eft

While on one of my daily nature walks I looked down and spotted one of the true beauties of the woods, a red eft (see photo). They wander around, especially after rains and are very slow-moving and unafraid. Of course there is a reason for this- they are protected by a very potent poison, tetrodotoxin. You cannot be poisoned by handling the young newt, but if you eat it your nerve cells will have some severe problems. The bright orange/red coloration of red efts, which are juvenile stages of the red-spotted newt, clearly warns potential predators to leave them alone. As the red efts mature into adults, they become more greenish-yellow (see second photo). The adults return to the water where the gilled larvae started life and spend the rest of their lives there. This "reverse" life history (embryos, gilled larvae and adults are aquatic, but juveniles are terrestrial) is in contrast to typical amphibians, where only the embryos and larvae are aquatic. While there is much about this process that is unclear, it does seem likely that such an alternation of generations between habitats is probably a means of minimizing competition for limited food resources. One strange thing is that not all populations of newts have an eft stage, perhaps due to unsuitability of land habitats or less competition for food in the water. A similar phenomenon may cause retention of gills in some populations of tiger salamanders (leading to presence of aquatic, reproductively adult axolotls that resemble gilled larvae).

Another really interesting feature of red efts is that they are probably mimicked by other amphibians such as the red salamander (see photo). This latter creature is apparently tasty but may be protected by its resemblance to the very toxic red eft. Isn't it intriguing how the color red has come to be used as both a warning and an attractant, for example as the prime color for flowers used for nectar by hummingbirds, and as the color of ripe fruits? Remember also that the recognition of the color red requires that an animal has color vision, which many mammals do not. So the target predators for this red-hued message by the efts is likely to be birds.

Here we have another example of the complex interactions that govern the lives and appearance of critters- just amazing!

-Bill Dunson

Galax, VA & Englewood, FL

A tiny legume destroyer- the Genista moth

Another one of those things that go on in our backyards without much notice is the occasional destruction of plant leaves by small caterpillars. Sometimes we get annoyed by this and spray the plants or try to figure out what is happening. In recent walks in scrub habitat at Lemon Bay Preserve I have noticed that many of the beautiful sky blue lupines, which are not yet in bloom, are being heavily damaged by a small caterpillar (see photo attached). I was unfamiliar with this species and searched the web to find out that it is well known as a destroyer of various legumes, including lupine and members of the genus Sophora which includes necklace pod in Florida.

The rest of the story is that this caterpillar is immune to the powerful toxins found in legumes, and indeed uses these poisons to defend itself against attacks by predators. If this reminds you of some other famous cases think about monarchs and milkweeds, and zebra butterflies and passion-vines. So here is another case of a larval insect stage making itself toxic by eating a poisonous plant. Consider what this means- that the ability to tolerate the toxins must have evolved over a very long period, and then coloration advertising the toxicity (aposematic or warning coloration) developed. Then predators must recognize the significance of the warning coloration, perhaps specifically or generically. Some predators such as lynx spiders apparently can handle the toxins and eat the caterpillars

(see this article).

Now the adult is distinctively colored (see photo from web) but I do not know if it is protected also.

So if we needed reminding that the natural world is amazingly complex and interesting, here is another case. The deeper we look the more we see, and the more impressive the web of life becomes. So get out there and groove on nature but don't eat the caterpillars!

-Bill Dunson, Englewood, FL