FIELD BOOK OF INSECTS. 



elytra rather densely clothed with gray pubescence. On 

 sumac and sassafras 0. ruficollis. 



Pale, dull yellow with a dark brown elytral stripe 



on each side O. gracilis. 



9. Elytra black ; head and pronotum red, the latter with a 

 black spot. On alder. Tetrops monostigma (elytra with 

 black hairs ; western) and T. canescens (elytra with grayish 

 hairs; eastern). 



Elytra red with black spots; head and pronotum red. 

 Tetraopes, of which the following are the more common 

 species. T. canteriator : pronotum with four round, black 

 spots; black areas on elytra form, when elytra are closed, 

 a heart-shaped space back of the middle; apex of elytra 

 also black; .3 to .5 in. long. T. tetraoplithalmus: pronotum 

 with four black spots near the middle and sometimes a 

 blotch in front and behind; see Plate LXXXII. T. 

 femomtus: a western species, resembles tetraophthalmus, 

 but the apex and base of each joint of antennae are nar- 

 rowly ringed with gray; .5 in., or more, long. They are 

 usually found late in summer on milkweed, in the stems 

 and roots of which they breed. They stridulate loudly. 

 The extent of the black markings varies somewhat. 



CHRYSOMELID^E 



The Chrysomelidae of the United States are never more 

 than moderately long, as beetles go; their antennae are 

 not very long, and their bodies are often chunky. Nearly a 

 thousand species are known from North America, about a 

 twentieth of the number known from the rest of the world. 

 One way of looking at the food habits of beetles is that 

 adopted by the celebrated Coleopterists, LeConte and 

 Horn: "As the function of the Cerambycidae is to hold 

 the vegetable world in check by destroying woody fiber, 

 the Bruchidae effect a similar result by attacking the seeds 

 and the Chrysomelidae by destroying the leaves." The 

 potato-grower would have to be a philosopher in order to 

 look at the Chrysomelid Leptinotarsa in that way. Not 

 all Chrysomelidae are leaf -eaters, however, as will be pointed 

 out in the course of the discussion. No attempt will be 

 made to enable the reader to identify a large proportion 



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