I read your article and when I checked my tree there were some golden colored beetles on the leaves. What do I do when I seen them in groups and some are on top of each other. Does that mean they are ready to mate or are they already in the process?
Will soapy water kill them? Otherwise I will have to buy some Permethrin?
Beetles on trees that appear in groups are usually mating. There are several species that could be involved and some have different behavior patterns but the common birch bark beetle, longhorned beetle and japanese beetle will group up when they have found mates and begin the reproducing process.
As explained in our JAPANESE BEETLE CONTROL article, foraging adults can cause a lot of damage to any plant they start to focus on. In the above listed article, you’ll see we mention INSECTICIDAL SOAP as the old organic standby which can be used to kill them. But it won’t provide any residual action and is clearly a “weaker” option compared to some other choices now available. This inherent limit of soap is more pronounced when dealing with a species of insect like beetles so one of the following concentrates would be a much better choice to apply for best results…
Two better choices of spray would be the other organic solution mentioned in the article, MULTIPURPOSE INSECT KILLER or the longer lasting VEGETABLES PLUS PERMETHRIN. Both will work much better than soap and will last a week or two per application. The strongest material you could use would be DELTAMETHRIN as it would last 2-4 weeks per treatment.
Certain trees are more susceptible to insects and birch trees seem to have many species interested in either eating or boring through their trunks. Any of the above listed products would help stave off these assaults and in the end prove helpful in letting your birch live a longer and healthier life.