34 



MISC. PUBLICATION 62 6, U. S. DEPT. OF AGRICULTURE 



Columbine Aphid 



The columbine aphid {Pergandeidia 

 trirhoda (Walk.)) is a small, cream- 

 colored, rather flat plant louse which 

 sometimes infests columbine in such 

 numbers as to require treatment. In- 

 festation usually occurs late in the 

 summer. Like other aphids, the colum- 

 bine aphids suck the plant juices from 

 the under side of the leaves and cause a 

 stunting of the plant growth. The bean 

 aphid (p. 63) also attacks columbine 

 at times. 



Treatment. — Same as recommended 

 for aphids (p. 9). 



Columbine Skipper 



The caterpillar of the columbine 

 skipper (Erynnis lucilius (Scud. & 

 Burg.)) chews holes in the leaves of 

 columbine and apparently confines its 

 feeding largely to this plant. When 

 not feeding, it hides in a rolled-up leaf. 

 The caterpillar is about % inch long 

 when full-grown, is velvety green, rather 

 stout, and has a small black head. The 

 adult is one of the butterflies that are 

 known as skippers. Several generations 

 of caterpillars are produced each year. 



Treatment. — Spray or dust with 

 lead arsenate to poison the caterpillars. 

 Spraying or dusting with pyrethrum or 

 derris may be effective against the very 

 small caterpillars. Where only a few 

 are present they can be picked off easily. 



Other Pests of Columbine 



Page 



Rose bud worm 83 



Black stinkbug 83 



Eastern tent caterpillar 47 



Red spiders 11 



Asiatic garden beetle 21 



COSMOS 



This popular flowering plant is sub- 

 ject to attack by a number of insects. 

 For the most part, however, these are 

 general feeders and have been discussed 

 under other plants. The insects most 

 frequently encountered are the follow- 

 ing: Page 



Bean aphid 63 



Potato aphid 75 



Spotted cucumber beetle , 7 



Asiatic garden beetle '. 21 



European corn borer 36 



Stalk borer 34 



Six-spotted leafhopper 20 



Four-lined plant bug 94 



Tarnished plant bug 35 



Red spiders 11 



DAHLIA 



Stalk Borer 



Several species of caterpillars have 

 the insidious habit of boring and tunnel- 

 ing through the stalks and stems of 

 fleshy and thick-stemmed plants, such 

 as aster, cosmos, dahlia, delphinium, 

 goldenglow, hollyhock, lily, peony, 

 phlox, and zinnia. The stalk borer 

 (Papaipema nebris (Guen.)) is the chief 

 offender in the flower garden. Before it 

 is discovered its work usually has pro- 

 gressed to the point where wilting and 

 breaking over of the plants occur. A 

 close examination of plants so affected 

 will disclose a small round hole in the 

 stem. This hole is the entrance to the 

 stalk borer's burrow and the opening 

 from which the castings are expelled. 

 By splitting the stalk lengthwise one 

 may find the culprit, a slender caterpillar 

 (fig. 55) which is a little over an inch 

 long when full-grown. The caterpillar 

 frequently moves from the stem of one 

 plant to that of another and con- 

 sequently may cause considerable 

 damage. The young caterpillar is 

 brownish and bears a dark-brown or 

 purple band around the middle of the 

 body, with several conspicuous brown 

 or purple stripes running lengthwise. 

 The grayish-brown moths occur late in 

 the summer and deposit their eggs for 

 the next season's brood on burdock and 

 ragweed as well as on a variety of other 

 plants. 





Figure 55. — A, Stem of goldenglow split 

 to show the stalk borer; B, entrance 

 hole to the stalk borer's burrow in 

 hollyhock stem. Slightly enlarged. 



