162 



This insect (the ten-lined or Colorado beetle) passes the winter in 

 the pupa state in the ground, and comes forth in the beetle state in 

 the spring, usually in May. 



The eggs, after being deposited on the leaves of the potato, hatch 

 out in about a week, and the young larvae at once commence devour- 

 ing the leaves, being most voracious feeders. In about two weeks, as 

 a general rule, they attain their full growth, cease eating and enter 

 the ground in order to undergo their transformations. In three or 

 four days they change into pupae or chrysalids, and in ten or twelve 

 days thereafter the perfect beetles make their appearance, making 

 about five weeks from the time the eggs are deposited until the beetle 

 appears. In Illinois, there are usually about three broods in the year; 

 yet there does not appear to be any great regularity as to broods taken 

 in mass; that is to say, the various changes and transformations of 

 individuals are not simultaneous, as beetles, larvae and eggs may 

 often all be seen at the same time. 



In addition to the potato, this insect, when very abundant also eats 

 the following plants: The common thistle, (Cirsium lanceolatum) , pig- 

 weed (Amaranthus retroflexus), hedge mustard (Sisimbrium officinale), 

 oats, knotweed, red currant, tomato, nightshade and lambs-quarter. 



Natural Ensmies. — Fortunately for our farmers and gardeners, and for 

 all who love potatoes, this dreaded foe had hardly commenced its 

 grand march to the Atlantic, when, one after another, insect friends 

 began to appear upon the field of battle as our allies, not in sufficient 

 numbers to stay the march of the vast hosts, yet sufficient to render 

 good service in harrassing the flank and in thinning out the stragglers. 

 Although there is but one real parasite in the long list of as ene- 

 mies (Lydella doryphorae,) yet they must ultimately assist very mate- 

 rially in keeping it in check ; and now that the great tidal wave has 

 passed beyond our State, I have little doubt but that this formidable 

 pest will gradually sink in notoriety from a first class obnoxious spe- 

 cies to second or third class, and perhaps even become less troublesome 

 than our old potato insects. 



The following is a list of the species which have been found de- 

 stroying this insect, chiefly while it is in the larvae state : 



Coleoptera. — 1. Tetracha virginica, Hope. 2. Pasimachus elongatus, 

 Lee. 3. Calasoma calidum, Fabr. 4. Harpalus caligiriosus, Say. 5. Le- 

 bia grandis. 6. Philonthus, ? sp. 7. Epicauta cinerea, Fabr. 8. Epicau- 

 ta vittata, Fabr. 9. Hippodamia maculata, DeG. 10. Hippodamia 18- 

 punctata. 11. Hippodamia convergent — Hippodamia glacialis. 12. Coccin- 

 ella 9-notata. 13. Mysia 15-punctata. 



Hemiptera. — 14. Reduvius raptatores,Sa,y. 15. Arma spinosa,Da\\a,s. 

 16. Harpactor cinctus, Fabr. 17. Coreus tristis, DeG. 18. Perillus circum- 

 cinctus, Say 19. Sliretrus jimhriatus, Say. 



Diptera. — 20. Promachus apivorus. Fitch. 21. Lydella doryphorae, 

 Kiley. 



Arachnida. — 22. Phalangium, , ?. 



Of these insects Nos. 1, 2, 3, 4, and 6 are ground beetles and are 

 predaceous, both in the larva and perfect state, and prey upon the 

 potato beetles and their larv.ro, chiefly while they are on the ground 

 undergoing their transformations. 



No. 5 (Lebia grandis) attacks them on the vines, and from all the 



