i2 4 AMERICAN SPIDERS 



hairs. When these come in contact with mucous membranes of 

 the eyes or nose of mammals or man, a very disagreeable urtica- 

 tion results, which persists for some time. In discouraging some 

 types of enemies, such as small mammals, this may be effective, al- 

 lowing the spider to escape while the aggressor is recovering from 

 the effects of the poison and is still partially blinded. (The bald 

 spot on the abdomen of tarantulas is often a result of a full use of 

 this covering of poisonous hairs; after each molt the spider is 

 provided with another even covering of hairs and setae.) Unfor- 

 tunately, this protective device can have no effect on those insect 

 enemies, the solitary wasps, which are most important as predators. 



The body hairs of tarantulas have long been known to have 

 in urticating effect on the skin of man; in allergic individuals they 

 often produce distressing symptoms. It is quite probable that a 

 toxic substance is present on the hairs, and the effect is not en- 

 tirely mechanical. Support for this view is seen in the fact that 

 alcohol in which these spiders have been preserved is capable of 

 producing the characteristic itching and stinging. 



Because all United States species are ground forms, their food 

 consists largely of the animals available in their restricted hunting 

 areas. Beetles and grasshoppers are most frequently captured, but 

 many other kinds of insects, and such crawling creatures as sow 

 bugs, some millipedes, and other spiders, fall to their lot. It is well 

 known that our species will kill and eat frogs, toads, mice, and liz- 

 ards in captivity, and it is reported that occasionally these small 

 creatures are captured in natural surroundings. During the summer 

 months the tarantula catches and eats insects almost every night, 

 frequently gorging itself. On the other hand, long periods of fast- 

 ing seem to have little effect on the spiders. In order to ascertain 

 just how long they could go without food, Baerg kept several of 

 them supplied only with water. One of the females lived two years 

 and four months without food, and other females almost matched 

 this record. 



Though the belief is more widely held than is justified, tarantulas 

 have long been known to capture and feed on small birds. The first 

 record of this behavior was published in 1705 by the Swiss natu- 

 ralist Maria Sibylla Merian in her Metamorphosis Insectorian Suri- 

 namensiitm. A fine color plate shows one of the South American 

 my gales in the act of feeding on a hummingbird. The spider, a 

 great brown creature said to belong to the genus Avicularia, has its 

 fangs imbedded in the breast of the gaily colored bird, which has 



