260 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 292.— A pig- 

 my locust. 



Fig. 293. — Acrydium granula'.um. 

 ley, after Kirby.) 



(From Blatch- 



Orthoptera believe they constitute a separate family. The most 

 striking character of the subfamily is the 

 shape of the pronotum. This is prolong- 

 ed backwards over the abdomen to or beyond 

 its extremity (Fig. 292). The head is deeply 

 set in the pronotum; and the prosternum is ex- 

 panded into a broad border, which partly 

 envelops the mouth-parts like a muffler. The antennee are very 

 slender and short. The tegmina are vestigial, being in the form of 

 small, rough scales; while the wings are usually well-developed. 

 These locusts differ, also, 

 from all others in having 

 no arolium between the 

 claws of the tarsi. 



The pigmy locusts are 

 commonly found in low, 

 wet places, and on the 

 borders of streams. 

 Their colors are usually 

 dark, and are often pro- 

 tective, closely resem- 

 bling the soil upon which 

 the insects occur. They 

 are very active and pos- 

 sess great leaping powers. 



Some of the species vary greatly in coloring; this has resulted 

 often in a single species being described under two or more names. 

 This is an exceedingly difficult group in which 

 to deteiTnine the species. 



Figure 293 represents Acrydium granuldtum 

 with its wings spread, and the pronota of two 

 color varieties. 



Figure 294 represents Acrydium arenosum 

 obsciirum, greatly enlarged, with its wings 

 closed. 



Family PHASMID^* 

 The Walking-Sticks and tJie Leaf -Insects 



The Phasmidee is of especial interest on ac- 

 count of the remarkable mimetic forms of the 

 insects comprising it. In those species that 

 are fotmd in the United States, except one in 

 Florida, the body is linear (Fig. 295), wingless, 

 and furnished with long legs and antennae. This peculiar form 

 has suggested the name walking-sticks which is commonly applied 



*This family is separated from the Orthoptera by Handlirsch ('o6-'o8) and 

 made to constitute a distinct order, the Phasmoidea. 



Fig. 294. — Acrydium 

 arenosum obscurum. 

 (From Hancock.) 



