HOW TO KNOW THE INSECS 



Figure 46, 



Fig. 46. Vespa maculata L. The Bald 

 Faced Hornet. 



Black with pale yellow markings. 

 Builds a very interesting gray paper 

 nest on trees. (And abundantly able 

 to defend it.) Length 20-24 mm. 



From the viewpoint of social ad- 

 justments and intelligence, the Hy- 

 menoptera probably ranks the highest 

 of any order of Insects. It is a 

 large order; some think that It will 

 be found to contain more species than 

 any other order of Insects. The Iowa 

 Survey collection contains many 



species, but of course, the work in the order is only started. 



Specimens should be mounted promptly when caught to keep them in 



good condition. 



11b Small, slender insects. Wings very narrow and margined 

 with bristly hairs. (Thrips) Fig. 47. Order XIII, THYSANOPTERA 



Fig. 47. A Thrips. Hellothrlps 

 haemorrho 1 dal 1 s (Bouche) The 

 Greenhouse Thrips. 



Dark brown. Feeds on foliage of 

 greenhouse plants. Larvae white. 

 Length about 1 mm. (U.S.D.A.) 



This Is but one of a large number 

 of species of thrips to be found in 

 Iowa. They may very frequently be 

 found in large numbers among the 

 stamens of the flowers of many spe- 

 cies of plants » They are also found 

 Figure 47. on leaves, bulbs, roots, under loose 



bark, and in decaying fruit. They 

 are always tiny but because of their 

 great abundance are frequently quite destructive. 

 12a Front wings much larger than hind wings. Wings held ver- 

 tical above body. Long fragile jointed tails behind. (May- 

 flies, or "Mormon-flies") Fig. 48. 



Order IV, EPHEMERIDA 



Fig. 48. Hexagenia llmbata Guerln 



Abdomen pale yellow, dorsal line and 

 oblique lateral stripes dark. Length 

 of body (without cercl) 15-22 mm. 



The L'ayflles are the only insects 

 that molt after once getting their 

 wings. Even then the adults live only 

 a day or two. They appear In flight 

 at lights in Immense numbers at towns 

 along rivers or lakes. Burlington, 

 Iowa has an authentic record of a pile 

 eight feet deep forming a. ound an elec- 

 tric light pole one night when a heavy 

 flight was in progress. Their nymphs 

 are especially valuable as food for fish 



42 



