No. 6. DEPARTMENT OF AGRICULTURE. 548 



4. Rotation of Crops. 



This practice sliould be followed for the sake of the strength of 

 the plants if not for the repression of insects. Many pests stay in- 

 one locality, and if the same kind of crop is grown consecutively for 

 many year® in the same soil the insects accumulate there and become 

 most serious. 



To rotate with plants that are similar and attacked by the same 

 insects will not avail much. The plants should be of widely differ- 

 ent character and any insects that remain are thus starved. 



5. Planting Trap Crops. 



This is done in two ways. One is to make a very early planting of 

 the kinds of plants to be set out later, intending to have the insects 

 infest this trap crop with their eggs and then destroy them. Often 

 it is desirable to start the trap plants indoors in order to have them 

 large enough for the insects to attack at once. vSometimes it is de- 

 sirable to spray the trap crop with kerosene or some other insecti- 

 cide that will be sure to kill the pests even though the plants are also 

 injured. Often it ie peesible to gather an early crop from the trap 

 plants before destroying them. For example, it is recommended to 

 plant traps of early summer squash to protect the winter varieties 

 to be planted later. 



The other method is to plant some kinds of plants that the insects 

 prefer to the ones we wish to raise. For example, this year w'e have 

 completely protected our squash from attacks of flea-beetles bj 

 planting a few potatoes around among the vines. These insects pre 

 fer the potato and other Solanaceous plants to the Cucurbitaceous, 

 and consequently when it was possible went to the former in place 

 of the latter. In fact, that is why we had to photograph a potato 

 and bean leaf instead of one from a Cucurbit to show the work of the 

 flea-beetle. They w^ere serious pests on our squash last year, but this 

 year none occurred on squash, cucumber or melons, all having pota- 

 to vine traps. This test has never before been made or published. 



6. Hand Picking. 



This consists in going over the plants every morning during the 

 weeks of the greatest abundance of the insects especially during the 

 mating season, and picking off or brushing the insects into oil and 

 water. This is especially to be recommended for squash bugs. The 

 board traps greatly facilitate this means of gathering the pests. It is 

 the best means of combatting the tomato worm, celery caterjullar and 

 many other conspicuous insects. Clusters of eggs should likewise 

 be picked off. 



7. Excessive Seeding. 



Wis consists in the well-known method of planting in one hill 

 more seeds than are to be grown, with the expectation that the in- 

 sects will destroy some. This is a good plan when it is necessary 



