Bernd Heinrich 



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later, I took the block out and let it thaw. 

 Once released from the grip of the ice, the 

 moths righted themselves, shivered for a 

 few minutes, and then flew off. They had 

 me hooked. 



Winter moths turned out to be much 

 easier to work with than many other moths 

 I had studied. I found I could catch large 

 numbers of them with stale beer, put them 

 into a jar with moist leaves or tissue, and 

 keep them healthy for months by storing 

 them in the refrigerator at about 32° F. 

 And I could catch them (usually the spe- 

 cies Eupsilia morrisoni) during any month 



Photographed at night, two winter moths, Lithophane hemina, left, and 

 EupsiUa morrisoni {far left) lap up a mixture of beer, sugar, and 

 mashed fruit that the author applied to a tree trunk. Below: Resting in 

 the late fall sunlight, Eupsilia transversa will be active in warm 

 winter weather and reproduce in the early spring. 



of the winter, provided there was a thaw of 

 a day or so and the snow cover was not too 

 deep. I caught many more species in late 

 winter to early spring. They had emerged 

 after passing the coldest months totally de- 

 veloped within the pupae. In March and 

 April, when the woodcock had returned 

 and was doing its mating dance on the first 

 bare patches of ground, I would paint 

 swaths of moth lure on the trees Uning my 

 driveway and watch as these insects — 

 with their beautifully subtle and muted 

 colors — gorged themselves before disap- 

 pearing with the next snowstorm. By late 

 April the trees were about ready to burst 

 into leaf, the first bats were flying again, 

 and tire warblers were returning. The win- 

 ter moths were near their end. 



The disappearance of winter moths just 

 as the birds are returning is no coinci- 

 dence; these predators have been a major 

 force in shaping the moths' behavior and 

 appearance. Early in their evolutionary 

 history, moths probably escaped most bird 

 predation by becoming nocturnal. But by 

 the Eocene, some 45 miUion years ago, 

 echolocating bats evolved, and moths 

 were again vulnerable at night. The late 

 Kenneth Roeder, of Tufts University, con- 



ducted experiments showing that some 

 motiis, in turn, have evolved ear structures 

 that allow them to hear the bats' sonar, 

 usually in time to take evasive action. 



Most moths, cryptically colored to 

 blend into bark or other specific back- 

 grounds on which they perch, rest motion- 

 less during the day. Some go beyond mere 

 pattern mimicry and resemble sticks, dry 

 leaves, and even bird droppings. Because 

 birds hunt by sight, detecting prey by 

 movement and contrast, they may fail to 

 detect a resting mofli. But as Alan Kamil, 

 a psychologist now at the University of 

 Nebraska, has demonstrated, blue jays can 

 learn to detect even the most well-camou- 

 flaged moth. Many moths have therefore 

 evolved other defenses to protect them- 

 selves during the day. Underwing moths 

 startle predators by flashing brilUant red, 

 yellow, or white underwings if they are 

 touched or otherwise disturbed while rest- 

 ing. Thus they get a second chance to es- 

 cape, usually by dropping to die ground. 

 Some large moths have amazingly lifelike 

 eye patterns on their underwings, and still 

 others, such as many of the diurnal tiger 

 moths, are brightly colored to advertise 

 that they are poisonous. 



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